MeteoExplorer 1.3

User Guide

 

February 2014


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

© 2014, EastModelSoft Laboratory. All right reserved


 

Contents

Chapter 1         Introduction to MeteoExplorer. 1

1.1             Introducing MeteoExplorer. 1

1.2             MeteoExplorer Primary Features. 1

1.3             Technical Advantages. 2

1.4             Use MeteoExplorer on Mobile Devices. 6

1.5             Online Resources. 7

Chapter 2         Installation and Configuration. 9

2.1             System Requirements. 9

2.2             Install MeteoExplorer. 9

2.2.1         Download. 9

2.2.2         Install MeteoExplorer under Windows. 9

2.2.3         Install MeteoExplorer under Linux. 14

2.3             Add Resource File. 15

2.3.1         Show/hide menus specified in menu resource file. 15

2.3.2         Customize nephogram palette. 16

2.4             Uninstall MeteoExplorer. 16

2.4.1         Uninstall MeteoExplorer under Windows. 16

2.4.2         Uninstall MeteoExplorer under Linux. 17

Chapter 3         MeteoExplorer Basics. 19

3.1             The Application Main Window.. 19

3.2             Menus. 20

3.2.1         File. 20

3.2.2         Edit. 21

3.2.3         Option. 21

3.2.4         View.. 22

3.2.5         Tools. 22

3.2.6         Help. 23

3.3             Toolbar. 23

3.4             Central Canvas. 25

3.4.1         Zooming, panning and rotating. 25

3.4.2         Zoom to the specified area. 27

3.4.3         Full screen mode. 28

3.5             Graphics Layer Management. 29

3.5.1         Graphics Layer Organization. 29

3.5.2         Basic Graphics Layer Operations. 31

3.5.3         Single Layer Operations. 32

3.5.4         Graphics Layer Navigation and Animation. 33

3.5.5         Differences in Graphics Layer Operations for Different Type of Data Files. 34

3.6             Thumbnail View.. 35

3.7             Status bar. 36

3.8             User Preferences. 36

3.8.1         Switch between software and hardware rendering. 37

3.8.2         Adjust screen contents based on map scale. 37

3.8.3         Smooth line strip when drawing synoptic chart. 40

3.8.4         Switch user interface language. 42

Chapter 4         GIS functionalities. 43

4.1             Cartographic Projection Settings. 43

4.2             Base Map Settings. 46

4.2.1         Theme. 46

4.2.2         Country and Region. 48

4.2.3         Topology Terrain. 49

4.2.4         Single State/Province Display and Shading. 50

4.2.5         Drawing Graphics inside a Region. 52

4.2.6         Show South China Sea. 53

4.2.7         World Administrative Areas, Map Scale, and Grid Lines. 54

Chapter 5         Page Layout. 57

5.1             Page Layout Design. 57

5.2             Select Page Layout View.. 58

5.3             Set Title and Legend with Information of a Graphics Layer. 60

5.4             Layout Setup. 62

5.4.1         Preview.. 62

5.4.2         Title. 63

5.4.3         Canvas. 64

5.4.4         Legend. 65

Chapter 6         Analysis and Visualization of Numerical Model Data. 69

6.1             WMO GRIB1/GRIB2 Data Visualization. 69

6.1.1         Universal Model Options Dialog. 70

6.1.2         Isoline Analysis of Gridded Field. 72

6.1.3         Change Layer Properties. 74

6.1.4         Stream Line Analysis of Wind Field. 77

6.1.5         Export Analytic Graphics Layers. 80

6.2             GrADS Data Visualization. 80

6.3             NetCDF Data Visualization. 81

Chapter 7         Surface Station Data Analysis and Display. 85

7.1             Configure Display Properties of Elements in Surface Station Data. 85

7.2             Objective Analysis of Elements in Surface Station Data. 88

Chapter 8         Upper-Air Soundings Data Analysis and Display. 95

8.1             Configure Display Properties of Elements in Upper-air Soundings Data. 95

8.2             Objective Analysis of Elements in Upperair Soundings Data. 97

Chapter 9         Single Element Station Data Analysis and Display. 101

9.1             Configure Display Properties of Station Observation Data. 101

9.2             Objective Analysis of Station Observation Data. 103

Chapter 10       Gridded Data Analysis and Display. 107

10.1          Configure Geographic Range for Isoline Analysis. 108

10.2          Configure Isoline Analysis Values. 110

10.3          Configure Isoline Display Properties. 112

10.3.1       Isoline Shading. 113

10.4          Smoothing. 117

10.5          Show Grid-Point Values. 118

Chapter 11       Vertical Soundings Data Analysis and Display. 121

11.1          Soundings Analysis Window Layout. 121

11.1.1       Toolbar. 122

11.1.2       Elements Selection and Properties Configuration. 123

11.1.3       Soundings Data Display Window.. 126

11.1.4       Wind Velocity Window.. 126

11.1.5       Physics Indices Data Display Window.. 127

11.2          Calculation of Physics Indices. 127

Chapter 12       Typhoon Track Data Display. 131

12.1          Configure Display Properties of Typhoon Track Data. 131

Chapter 13       City Forecast Data Display. 133

13.1          Configure Display Properties of City Forecast Data. 133

Chapter 14       Streamline Data Analysis and Display. 135

14.1          Configure Display Properties of Streamline Data. 135

14.2          Calculating Derived Physics Elements from Wind Field. 138

Chapter 15       Interactive Composition of Synoptic Chart. 141

15.1          Introducting Synoptic Scale Toolbox. 141

15.2          Using Synoptic Scale Toolbox. 144

15.2.1       Point-Type Weather Symbol 144

15.2.2       Vector-Type Weather Symbol 145

15.2.3       Binary Choice Point-Type Weather Symbol 145

15.2.4       Line-Type Weather Symbol 146

15.2.5       Modification of Line-Type Weather Symbol 147

15.2.6       Move and Cut of Weather Symbol 150

15.3          Undo and Redo. 151

15.4          Automatic Save. 151

Chapter 16       Meso-Scale Weather Analysis. 153

16.1          Introducing Meso-Scale Toolbox. 153

16.2          Using Meso-Scale Toolbox. 154

16.2.1       Point-Type Weather Symbol 154

16.2.2       Vector-Type Weather Symbol 155

16.2.3       Line-Type Weather Symbol 155

16.2.4       The Rest Weather Symbols. 155

16.3          Automatic Save. 155

Chapter 17       Nephogram and RADAR Data Display. 157

17.1          Configure Palettes for Nephogram.. 157

17.2          RADAR Data Display. 160

17.3          Configure Palettes for Multi-Channel High-Resolution Nephogram.. 161

17.4          Customize Palette. 163

17.5          Animation. 164

Chapter 18       Cross Section Graphics. 165

18.1          Preparation. 165

18.1.1       Toolbar. 165

18.1.2       Specify the data source files. 166

18.1.3       Plot a Apatial Location. 167

18.2          Create and Configure Cross Section Graphics Layer. 169

18.2.1       Create a Cross Section Graphics Layer. 169

18.2.2       Configure Display Properties of a Cross Section Graphics Layer. 169

18.2.3       Modification of Vertical Range. 171

Chapter 19       New Type Data Display. 173

19.1          Stamp Graphics Display. 173

19.2          L-Band Soundings Data Analysis and Display. 174

19.3          ESRI Shapefile Display. 175

Chapter 20       Weather Map Export. 179

20.1          Save as Image File. 179

20.2          Save as Windows EMF file. 179

20.3          Copy to Clipboard. 179

 

 


Chapter 1           Introduction to MeteoExplorer

1.1     Introducing MeteoExplorer

MeteoExplorer is a cross-platform software for analyzing and rendering atmospheric science and geoscience data. It supports popular data formats including WMO GRIB1/GRIB2, NetCDF, GrADS, and MICAPS, and provides some basic GIS functionalities. Developed with C++, MeteoExplorer as a native application enjoys the advantages of providing high performance while at the same time requiring low system resources. MeteoExplorer is designed to support all popular desktop platforms including Microsoft Windows, GNU Linux, and SGI Irix operating systems.

1.2     MeteoExplorer Primary Features

Below is a list summarizing the primary features of MeteoExplorer:

l  Graphics layer management (show, hide, properties configurations, navigation and animation);

l  Objective analysis of physical elements in surface or upperair soundings data;

l  Isoline analysis and shading of gridded field;

l  Streamline analysis of wind field;

l  Computation of physics elements;

l  NetCDF data process and display;

l  WMO GRIB1/GRIB2 data process and display;

l  GrADS data process and display;

l  MICAPS data process and display;

l  ESRI shapefile process and display;

l  Satellite nephogram data display and animation, support AWX, GPF and HDF format;

l  Interactive composition of synoptic chart (command undo/redo, automatic save);

l  Meso-scale synoptic analysis;

l  Creation of cross-section graphics;

l  Map zoom, pan, projection and clipping;

l  Full screen display and zoom to area;

l  Page layout and configuration;

l  Quick navigation via thumbnail view of graphics layers;

l  Save screen shot as image file (support formats: BMP, JPG, PNG);

l  Vector graphics exported to clipboard or saved as EMF file (Windows version only);

l  System configuration (dynamic menu);

l  Fast switch of user interface language on the fly.

 

 

1.3     Technical Advantages

Compared with other meteorological and geographic information system software, MeteoExplorer enjoys the following advantages:

 

1, Cross-platform support

 

MeteoExplorer is designed to support as many mainstream platforms as possible from the very beginning, so that users may use MeteoExplorer in their favorite platforms. In addition, to maximize runtime performance, MeteoExplorer is implemented as a native application instead of an interpreted application like that implemented in JAVA or .NET. For now MeteoExplorer supports Windows XP/Vista/7/8, Redhat Enterprise Linux 5/6, and SGI Irix operating systems. Figure  11 shows the screenshots of MeteoExplorer running under Windows XP (A), Windows Vista (B), Redhat Enterprise Linux 5 (C), and SGI Irix (D).

 

(A) Windows XP

(B) Windows Vista

(C) Redhat Enterprise Linux 5

(D) SGI Irix 6.5

Figure 11: MeteoExplorer supports Windows XP/Vista/7/8, Redhat Enterprise Linux 5/6, and SGI Irix operating systems.

 

2, Runtime performance and user experience matter

 

With the rapid development of atmospheric science and meteorological technologies, researchers and professionals demand their productivity tools to be capable of delivering higher efficiency and graphics rendering performance, that is, they hope the tools can analyze and visualize more volume data in less time. With these requirements in mind, MeteoExplorer is designed to emphasize performance from the very beginning, and to hopefully bring fluid user experience and promote working productivity of users. In practical implementation, we choose C++ for native development, instead of interpreted programming languages such JAVA, C# and Visual Basic, to maximize program performance, while as the same time reduce application requirements for system resources. In addition, we make use of OpenGL and DirectX hardware acceleration technology to enhance graphics rendering speed. Both of the approach aim to bring fast, fluid user experience.

 

3, Vector graphics output in a what-you-see-is-what-you-get way

 

In atmospheric science operations and research, the demands from researchers and professionals have increased tremendously. They hope an application can not only analyze and visualize more volume data in less time, but also export the rendered screen contents to an image file of various formats. In this way, they can use the exported image files as part of their products and research results in presentation or publications.

To meet the demand, a multifunctional graphics rendering engine that incorporating multiple graphics rendering technologies is proposed. This engine has the following advantages. First, it not only provides high rendering performance enjoyed by hardware acceleration rendering technology, but also supports vector graphics output thanks to the software rendering technology. Second, for the application powered by the proposed engine, the rendering technology can be switched from one to another on the fly and the application restart is not required. The display properties of the graphics and images are preserved after the switch. Third, it is convenient to port the proposed rendering engine to operating systems and computing devices of different architectures. Fourth, it is able to generate image file of various compression formats. The proposed graphics rendering engine has been implemented into MeteoExplorer.

Figure  12 gives an illustration that the rendering contents of Figure  1‑1B is copied and then pasted into Microsoft Word. Figure  20‑1 (page 180) provides another example that the same content is pasted into Microsoft PowerPoint.

The formats of exported graphics include both raster graphics such as JPG, BMP, and PNG, and vector graphics such as Windows Enhanced Meta Format (EMF), which is required by most academic journals and technical publications thanks to its lossless attribute insensitive to image zoom.

 

Figure 12: In MeteoExplorer, the screen content can be copied to the system clipboard and therefore used by other applications. In this figure, the clipboard content is copied into Microsoft Word.

 

4, Advanced objective analysis technology

 

MeteoExplorer provides advanced objective analysis method that meets the requirements of real-world weather analysis operation. Isolines of analytical field not only agree well with observatory station data, but are as elegantly smooth as those manually drawn by forecasters. An example is given in Figure  13 that shows the analytical field of 500hPa geopotential field on March 23, 2012.

 

Figure 13: Objective analytical field of 500hPa geopotential field on March 23, 2012.

 

5, Support all popular atmospheric science data formats

 

As the main functionality of MeteoExplorer is to analyze and visualize atmospheric science data, it has to support as many data formats as possible. For now MeteoExplorer supports WMO GRIB1/GRIB2, NetCDF, HDF, GrADS, MICAPS, and ESRI shapefile.

By providing support for the mainstream atmospheric science data, we hope to help users increase their productivity so that they may concentrate more on work or research while at the same time spend less time on chores of processing data.

Figure 14: MeteoExplorer supports WMO GRIB1/GRIB2, NetCDF, HDF, GrADS, MICAPS, and ESRI shapefile. This figure shows the analytic result of a NCEP global forecast system (GFS) data encoded in WMO GRIB2 format.

 

MeteoExplorer is able to not only analyze physical elements in the original data set, but calculate derived elements as well. For example, MeteoExplorer can calculate potential temperature, potential vorticity and so on from basic elements like pressure, temperature, and wind. The process of calculating derived elements can be referenced in Chapter 6 (page 69). Figure  14 shows the analytic result of a NCEP global forecast system (GFS) data encoded in WMO GRIB2 format. In the figure, the green contours represent 500hPa geopotential height field and the shaded contours represent geopotential height field at 1.5 geopotential vorticity unit.

1.4     Use MeteoExplorer on Mobile Devices

Over the past couple of years, the industry of information technology has enjoyed a fast paced evolution, in which mobile computing devices such as smart phones, tablet computers have formed a new computing platform that is as important as traditional personal computers like desktop and laptop computers. There mobile devices, with the advantages of being convenient to carry, long standby time, and an intuitive touch-oriented manipulations, have been playing more and more roles in both personal and enterprise computing.

In the field of atmospheric science and geographic information science (GIS), software support is the key for these all-new mobile computing devices to play their parts. It is necessary to port existent software applications that target desktop computers to mobile devices. MeteoExplorer touch is such an endeavor to port desktop-oriented MeteoExplorer to mobile-oriented Windows 8 and Windows RT. Figure 15 shows the screen shot of MeteoExplorer Touch running on Windows RT operating system.

 

Figure 15: Screenshot of MeteoExplorer Touch running on emulated Microsoft Windows RT operating system.

 

MeteoExplorer touch is a certified Windows store application and provides a native experience in that:

l  It focuses on information by offering a fully immersive experience.

l  It implements a fully hardware accelerated graphics rendering engine.

l  It participates in the Metro style experience in Windows 8 by including Appbar, application execution state management, device orientation handling and so on.

l  The interface and controls are designed to be there when you need them and out of view when you don’t.

l  It provides the stick-to-your-finger responsiveness of the touch support for panning and zooming.

 

For users of interested, please visit home page of MeteoExplorer Touch at www.eastmodelsoft.com/software/metouch.htm to get more information.

1.5     Online Resources

If you have any questions or want to give us your suggestions, please visit the home page of MeteoExplorer at www.eastmodelsoft.com/software/mexplorer.htm to get more information, including notes of latest software release, help documentations, email support, and discussion forum.


Chapter 2           Installation and Configuration

2.1     System Requirements

Supported operating systems

l  Microsoft Windows XP/Vista/7/8;

l  Red Hat Enterprise Linux (RHEL) 5/6;

l  SGI Irix 6.5;

 

Processor and RAM

X86 PC: Intel Pentium 2.4GHz with 1GB RAM is minimal; Intel Core 2 Duo 1.5GHz with 2GB RAM is recommended.

SGI RISC workstation: MIPS R16000A 800MHz with 1GB RAM.

 

Graphics adaptor and display

The graphics adaptor should support at least OpenGL 1.2 or DirectX 9;

Screen resolution of 1024×768 pixels is minimal; 1600×900 is recommended.

2.2     Install MeteoExplorer

2.2.1    Download

One can visit MeteoExplorer download web page at www.eastmodelsoft.com/downloads.htm to download the latest release of MeteoExplorer.

2.2.2    Install MeteoExplorer under Windows

In spite of the fact MeteoExplorer for Windows is released in 32-bit binary, thanks to the WoW64 (Windows 32-bit on Windows 64-bit) emulator of Windows operating system, MeteoExplorer can run under both 32-bit and 64-bit Windows.

You need to download either the file ‘me-win32-1.3.nnnn-setup.zip’ or the file ‘me-win32-1.3.nnnn- files.zip’, where nnnn stands for the build number. The larger value of this number, the newer the release. The former file is a standard Windows installer that is recommended to most users; the latter file is indeed a compressed file containing the binary, library, resource, and documentation files of MeteoExplorer. Users need to uncompress the downloaded file first. For the latter file, one can execute the file ‘mexplorer.exe’ from the extracted folder to launch MeteoExplorer. So no installation process is required. For the former file, there are two files (mesetup.exe and MeSetup.msi) and one folder (vcredist_x86).

To begin the setup process, all one has to do is to execute mesetup.exe. First the welcome screen pops up as shown in Figure Figure 21.

 

Figure 21The first step of MeteoExplorer installation process: the welcome screen.

 

Click “Next” to enter the select installation folder page (Figure Figure 22).

Figure 22: MeteoExplorer installation folder selection page.

 

In the ‘Select Installation Folder’ page, one may change the installation folder of MeteoExplorer. In addition, one can also choose whether to install MeteoExplorer for yourself, or for anyone who uses the computer. Select “Everyone” to install the program menus and desktop shortcut of MeteoExplorer to the shared system menu; select ”Just me” to install the program menus and desktop shortcut of MeteoExplorer to user’s private menu. After the selection, click “Next” to enter the ‘Confirm Installation’ page (Figure Figure 23).

 

Figure 23: MeteoExplorer ‘Confirm Installation’ page.

 

In the ‘Confirm Installation’ page, one may click “Next” to start the installation process, or click ”Cancel” to cancel the installation process. One may also click “Back” to go back to the previous steps and change settings if necessary.

Figure 24: The ‘Installing MeteoExplorer’ page.

 

Figure Figure 24 is a screen shot of ‘Installing MeteoExplorer’ page. As MeteoExplorer depends only on Microsoft Visual C++ x86 redistributable, the installation process should take less than one minute to complete. After a successful installation, the ‘Installation Complete’ page should appear as shown in Figure Figure 25.

Figure 25: After a successful installation, the ‘Installation Complete’ page should appear.

 

After a successful installation, the program menus and desktop shortcut of MeteoExplorer is added to the system.

2.2.3    Install MeteoExplorer under Linux

Unlike Windows operating system, there is no WOW64 equivalent simulator in Linux. As a result, users have to determine if her operating system is 32-bit, or 64-bit. A simple method to detect the system is run the uname command.

$ uname -a

where the parameter ’a’ stands for output all information. In the output information, one should check the words like i686, i386, or x86_64. If one sees x86_64, then her system is 64-bit, otherwise here system may be 64-bit.

For 32-bit system, one should download the file ‘install.sh’ and ‘me-linux-1.3.nnnn-i386.tar.gz’. For 64-bit system, one should download the file ‘install.sh’ and ‘me-linux-1.3.nnnn-x86_64.tar.gz’. After the download, one has to put the two files in the same folder and execute the installation script ‘install.sh’ with root privilege:

$ chmod +x install.sh

$ su

Password: [enter your password for root account]

# ./install.sh /opt

Remove old files …

Copy installation files to /var/mexplorer

Done.

 

By default, MeteoExplorer is installed to /usr/local/meteoexplorer. However, the installation script ‘install.sh’ accepts one parameter that is used as the installation folder. To change the installation folder, the user may provide a customized folder as illustrated in the example above, in which MeteoExplorer is installed to /opt/meteoexplorer.

2.3     Add Resource File

MeteoExplorer support MICAPS resource files including menu resource file, nephogram palette resource file and so on. To use your own resource files, all one has to do is to copy her files to the MeteoExplorer installation folder. By default, the Windows installation is ‘C:\Program Files\EastModelSoft\MeteoExplorer’, the Unix/Linux installation is ‘/usr/local/meteoexplorer/bin’.

2.3.1    Show/hide menus specified in menu resource file

A bundle file in MICAPS contains a number of entries, each of which serves as a wildcard referencing certain meteorological data files. A menu resource file contains a cascade of entries, each of which specifying a bundle file. Only one menu resource file is used by MeteoExplorer and the file has to be named as ‘micapsDataMenu.txt’ and copied to MeteoExplorer installation folder.

MeteoExplorer by default does not show the menu items given by the menu resource file, even if there exists one. To show the corresponding menus, the user may select the menu item ”Option, Show Data Menu”.

The formats of the MICAPS menu resource file can be referenced in MICAPS user manual.

Figure 26: MeteoExplorer supports MICAPS menu resource file.

 

2.3.2    Customize nephogram palette

MeteoExplorer supports MICAPS nephogram palette resource file. A nephogram palette is divided into four categories: infrared (I), RADAR reflection (R), visibility light (V), and Watervapor (W). There are at most ten palettes for each category with indices 00 to 09. So the third palette in the RADAR reflection category should be named as R-02.pal. MeteoExplorer by default provides 10 palettes for each of the four categories. Nonetheless, users can replace the default palettes with their own palettes by copying the palette resource files to the MeteoExplorer installation folder. The formats of the MICAPS nephogram palette resource file can be referenced in MICAPS user manual.

 

2.4     Uninstall MeteoExplorer

2.4.1    Uninstall MeteoExplorer under Windows

There are two ways to uninstall MeteoExplorer under Windows. The first method is to use ‘Programs, Uninstall a program’ in control panel. In the dialog (Figure  27), select Meteo Explorer and then click “Uninstall” button.

 

Figure 27: One way to uninstall MeteoExplorer under Windows is to use ‘Programs, Uninstall a program’ in control panel.

 

The second method is to select ‘Uninstall MeteoExplorer’ shortcut in program menus of MeteoExplorer, which can be found from ‘Start, All Programs, MeteoExplorer’.

2.4.2    Uninstall MeteoExplorer under Linux

To uninstall MeteoExplorer under Linux, just remove the MeteoExplorer installation folder. For example, if MeteoExplorer is installed in folder ‘/usr/local/meteoexplorer’, execute the following commands:

$ cd /usr/local

$ su

Password: [enter your password for root account]

# rm –rf meteoexplorer

 

Notes that the last command require root privilege.

 

 


Chapter 3           MeteoExplorer Basics

3.1     The Application Main Window

The main window of MeteoExplorer is shown in Figure Figure 31 (Windows release) and Figure Figure 32 (Unix/Linux release).

Figure 31: The user interface of MeteoExplorer’s main window under Windows 7.

 

The design of MeteoExplorer user interface (UI) follows the general guide line of a desktop Windows application. The user interface contains title bar, menus, tool bar, central canvas, auxiliary window (layer management window in the figures), and status bar. The Windows and Unix/Linux release share the same UI layout but different styles, in particular icons. This design choice makes the UI of MeteoExplorer to be consistent with the operating system.

 

Figure 32: The user interface of MeteoExplorer’s main window under CentOS Linux 5.

 

3.2     Menus

Application menus provide a comprehensive way for users to access all features of MeteoExplorer. The following subsections introduce the functions of each top-level menu of MeteoExplorer.

3.2.1    File

Table  3‑1 lists all the menu items along with their functions under the ‘File’ menu.

 

Table 31: The menu items along with their functions under the ‘File’ menu.

Menu Item

Function

Shortcut

New

Create a new synoptic char layer. See Chapter 15.

Ctrl+N

Open

Open a data file and create a graphics layer after a successful analysis of the data.

Ctrl+O

Save

Save the current edited synoptic chart to MICAPS-format data file.

Ctrl+S

Save As

Save the current edited synoptic chart to MICAPS-format data file, but with another file name.

Ctrl+A

Save As Image

Save the rendering contents of main window to an image file. Supported formats include bitmap (BMP), Joint Photographic Experts Group (JPG), and portable network graphics (PNG). See Chapter 20.

Not Available (NA)

Export As EMF

Save the rendering contents of main window to an EMF file. See Chapter 20.

NA

Exit

Exit the application.

Ctrl+Q

 

3.2.2    Edit

Table  3‑2 lists all the menu items along with their functions under the ‘Edit’ menu.

 

Table 32: The menu items along with their functions under the ‘Edit’ menu.

Menu Item

Function

Shortcut

Undo

Undo the last modification in editing the synoptic chart. See Chapter 15.

Ctrl+Z

Redo

Redo the last modification in editing the synoptic chart. See Chapter 15.

Ctrl+Y

Copy

Copy the rendering contents of main window to the system clipboard. For Windows build, the copied contents are encoded in EMF format; For Unix build, the contents are encoded in bitmap format. See Chapter 20.

Ctrl+C

Insert, Picture

Insert a picture from a disk image file to the current edited synoptic chart. See Chapter 15.

NA

 

3.2.3    Option

Table  3‑3 lists all the menu items along with their functions under the ‘Option’ menu.

 

Table 33: The menu items along with their functions under the ‘File’ menu.

Menu Item

Function

Shortcut

Preferences

Open “User Preferences” dialog to allow users configure all application preferences. See section 3.8.

NA

Projection and Map

Open “Map and Projection” dialog to let users configure cartographic projections and map parameters. See Chapter 4.

NA

Customize Layout

Customize layout of central canvas. See Chapter 5.

NA

Show Data Menu

Show or hide menus imported from MICAPS menu resource file. See section 2.3.1.

NA

 

3.2.4    View

Table  3‑4 lists all the menu items along with their functions under the ‘View’ menu.

 

Table 34: The menu items along with their functions under the ‘View’ menu.

Menu Item

Function

Shortcut

Graph Layer Manager

Show or hide graphics layer management window. See section 3.5.

NA

Thumbnail View

Toggle between overlaid view and thumbnail view of all graphics layers. See section 3.6.

NA

Layout, Browse View

Set the layout of central canvas to browse view. See section 5.1.

NA

Layout, Image Export View

Set the layout of central canvas to image export view. See section 5.1.

NA

Go To, Previous Time Instance

Step back one time instance and create a new graphics layer for the element corresponding to the select graphics layer. The new graphics layer will replace the old one. See section 3.5.

Alt+Left

Go To, Next Time Instance

Step forward one time instance and create a new graphics layer for the element corresponding to the select graphics layer. The new graphics layer will replace the old one. See section 3.5.

Alt+Right

Go To, Lower Level

Move downwards the adjacent lower level and create a new graphics layer for the element corresponding to the select graphics layer. The new graphics layer will replace the old one. See section 3.5.

Alt+Down

Go To, Higher Level

Move upwards the adjacent higher level and create a new graphics layer for the element corresponding to the select graphics layer. The new graphics layer will replace the old one. See section 3.5.

Alt+Up

Time Animation

Start time animation. See section 3.5.

NA

Time Interval

Choose the time interval for time animation.

NA

Zoom to Area

Zoom and pan the base map so that it will fit to the specified area. See section 3.4.2.

NA

Full Screen

Toggle between full-screen and windowed mode. See section 3.4.2.

F11

 

3.2.5    Tools

Table  35 lists all the menu items along with their functions under the ‘Tools’ menu.

 

Table 35: the menu items along with their functions under the ‘Tools’ menu.

Menu Item

Function

Shortcut

Synoptic-Scale Toolbox

Open synoptic-scale chart composition toolbox. See Chapter 15.

NA

Meso-Scale Toolbox

Open meso-scale chart composition toolbox. See Chapter 16.

NA

Create Cross Section

Open the ‘Cross-Section’ auxiliary window to allow users create cross-section graphics. See Chapter 18.

NA

 

3.2.6    Help

Table  3‑6 lists all the menu items along with their functions under the ‘Help’ menu.

 

Table 36The menu items along with their functions under the ‘Help’ menu.

Menu Item

Function

Shortcut

Contents

Open “MeteoExplorer User Guide” documentation with the default PDF viewer on users’ system.

F1

MeteoExplorer Home page

Open MeteoExplorer home page at www.eastmodelsoft.com/software/mexplorer.htm to get oneline resources.

NA

About MeteoExplorer

Open “About MeteoExplorer” dialog to show the build number, copyright information.

NA

 

3.3     Toolbar

Toolbar of MeteoExplorer provides users with a more convenient access to the mostly used functions. Each toolbar button corresponds to a menu item and shares the same function of that menu item. Table  3‑7 summarizes all toolbar buttons along with their functions.

 

Table 37: MeteoExplorer toolbar buttons along with their functions.

Toolbar button

Icon of Windows build

Icon of Linux build

Function

New

Create a new synoptic char layer. See Chapter 15.

Open

Open a data file and create a graphics layer after a successful analysis of the data.

Save

Save the current edited synoptic chart to MICAPS-format data file.

Undo

Undo the last modification in editing the synoptic chart. See Chapter 15.

Redo

Redo the last modification in editing the synoptic chart. See Chapter 15.

Copy

Copy the rendering contents of main window to the system clipboard. For Windows build, the copied contents are encoded in EMF format; For Unix build, the contents are encoded in bitmap format. See Chapter 15.

View, Home

Restore the zoom scale and pan offset to initial values.

Graphics Layer Manager

Show or hide graphics layer management window. See section 3.5.

Thumbnail View

Toggle between overlaid view and thumbnail view of all graphics layers. See section 3.6.

Layout

Set the layout of central canvas to browse view or image export view. See section 5.1.

Synoptic-Scale Toolbox

Open synoptic-scale chart composition toolbox. See Chapter 15.

Create Cross Section

 

Open the ‘Cross-Section’ auxiliary window to allow users create cross-section graphics. See Chapter 18.

Go To, Previous Time Instance

Step back one time instance and create a new graphics layer for the element corresponding to the select graphics layer. The new graphics layer will replace the old one. See section 3.5.

Go To, Next Time Instance

Step forward one time instance and create a new graphics layer for the element corresponding to the select graphics layer. The new graphics layer will replace the old one. See section 3.5.

Go To, Lower Level

Move downwards the adjacent lower level and create a new graphics layer for the element corresponding to the select graphics layer. The new graphics layer will replace the old one. See section 3.5.

Go To, Higher Level

Move upwards the adjacent higher level and create a new graphics layer for the element corresponding to the select graphics layer. The new graphics layer will replace the old one. See section 3.5.

Time Animation

Start time animation. See section 3.5.

Time Interval

Choose the time interval for time animation.

 

3.4     Central Canvas

3.4.1    Zooming, panning and rotating

Standard zoom: To zoom in, double click left mouse button or move the mouse wheel forward; to zoom out, double click right mouse button or move the mouse wheel backward.

 

Smooth zoom: smooth zoom differs from standard zoom in that the zoom scale changes smoothly during the manipulation. To zoom in, hold the middle mouse button and move forward; to zoom out, hold the middle mouse button and move backward. Release the mouse button to end the manipulation.

 

Rubber band box zoom: Press and hold Ctrl key and right mouse button, then drag the mouse and create a rubber band box that starts from the initial position and ends at current mouse position (Figure Figure 3‑3). Release the mouse to end the manipulation. The geographic area defined by the rubber band box is zoomed to the entire canvas (Figure Figure 34).

 

 

Figure 33: To do a rubber band box zoom manipulation, press and hold Ctrl key and right mouse button, then drag the mouse and create a rubber band box (the red box in this figure) that starts from the initial position and ends at current mouse position.

 

PanHold the left or middle mouse button and then drag. Release the mouse button to end the manipulation. When mouse is moved inside the central canvas, the geographic position (longitude and latitude value) corresponding to the mouse pointer position is shown on the status bar.

 

Reset zoom and pan offset to initial values: click the ‘Home’ button on toolbar to reset the zoom scale and pan offset to initial values.

 

Figure 34Release the mouse to end a rubber band box zoom manipulation. The geographic area defined by the rubber band box is zoomed to the entire canvas.

 

3.4.2    Zoom to the specified area

The zoom-to-area feature helps users to precisely define a geographic region that occupies the entire canvas. To do this, one may select the menu item ‘View, Zoom to Area’ to open the ‘Zoom to Area’ dialog (Figure Figure 35). In the dialog, one may enter value of start (end resp.) longitude (latitude resp.) and then click “OK” button.

 

Figure 35: MeteoExplorer provides zoom-to-area feature to help users to precisely define a geographic region that occupies the entire canvas

 

In this example, we specify the longitude range to be east 70~130 degrees, and latitude range to be north 15~55 degrees. The zoomed map is shown in Figure Figure 36.

 

Figure 36: The zoomed map after the user specifies the longitude range to be east 70~130 degrees, and latitude range to be north 15~55 degrees.

 

Tip: In MeteoExplorer, east hemisphere corresponds to 0~180 degrees, west hemisphere corresponds to -180~0 degrees; north hemisphere corresponds to 0~90 degrees, and south hemisphere corresponds to -90~0.

3.4.3    Full screen mode

MeteoExplorer supports full screen display mode, though by default it runs in windowed display mode. To toggle between these two modes, users may select menu item “View, Full Screen” or press F11 key. In full screen display mode, users may also press ESC key to switch back the windowed display mode.

3.5     Graphics Layer Management

3.5.1    Graphics Layer Organization

In MeteoExplorer, a graphics layer is logically a set of graphics objects that form a collection. In practice, a graphics layer can either a collection of weather symbols, or a complex synoptic chart that consists of station observations, contours, troughs, and so on. In general, MeteoExplorer creates a graphics layer from a data file. This practice is similar to the graphics layer concept in other meteorological applications.

When a graphics layer corresponding to a data file consists of information of a single element at a single time instance and at a single level (for example, a graphics layer that represents 2013-02-20_12:00:00 500hPa geopotential height), we can perform a number of operations to the layer. Such operations include but are not necessarily limited to show, hide, edit, view file content, remove, refresh, navigate, and configure display properties. A description of these operations can be referenced in Table  38. Under such an organization, all graphics layers are arranged in a linear form. So in the graphics layer management window of MeteoExplorer 1.2 (Figure 37), each graphics layer is represented by one list item.

When a graphics layer is used to represents a numerical model output data file, which consists of multiple physics elements, each of which in turn has several time instances and levels, the operations mentioned in the last paragraph no longer seem appropriate. For example, what does navigation mean for such a graphics layer?

In order to apply the aforementioned operations to graphics layers of different types, we enhance the graphics layer management functionality in MeteoExplorer 1.3. In the new graphics layer management scheme, all graphics layers are organized into a tree structure (Figure  38), with each layer corresponding to a tree node. The tree nodes are classified into two categories based on their depth level. The node with depth level of one correspond to the graphics layer created from a data file; whereas the node with depth level of two represents the graphics layer created by analyzing the given element at given time instance and level from a numerical model data set. A graphics layer of level two is always a child of a graphics layer of level one, therefore can be called sub-layer. Let us illustrate the organization scheme with Figure  38. This figure shows that the user has opened three data files: the first file contains the data of a 850hPa temperature gridded field. The second one is a NCEP data file encoded in WMO GRIB2 format. Two sub-layers are created by analyzing 500hPa geopotential height field and 500 hPa temperature filed in the NCEP data. The third file corresponds to a composed synoptic chart. As shown in the figure, MeteoExplorer use three level-one tree nodes to represent the graphics layers created from a data file, and two level-two tree nodes to denote the graphics sub-layers created by analyzing a single element in the NCEP data.

 

Figure 37: The old graphics layer organization use a linear style in which each list item corresponds to a graphics layer, as shown in the graphics layer management window of MeteoExplorer 1.2.

 

To facilitate users’ manipulation of graphics layers, MeteoExplorer provides a few features:

1.       If a graphics layer has a contour, the contour color will be used as the color of title text shown in graphics layer window. Otherwise, the color of title text is black or gray, depending on the visibility of the layer.

2.       When a graphics layer is hidden, its title in graphics layer window is drawn in gray.

3.       For a numerical model data file that consists of multiple elements, levels and times, the icon of the corresponding layer is represented with ; By contrast, the icon of a simple data file is .

4.       The icon of the current edited graphics layer is represented with .

5.       When a graphics layer is selected, the background of its title text is highlighted in blue.

 

Figure 38: In the graphics layer management scheme of MeteoExplorer 1.3, all graphics layers are organized into a tree structure, with each layer corresponding to a tree node.

 

3.5.2    Basic Graphics Layer Operations

Table  38 describes the graphics layer operations provided by each button of graphics layer management window.

 

Table 38: The graphics layer operations provided by MeteoExplorer.

Button name

Description of the operation

Show

Show the selected graphics layers in the main window of the application.

Hide

Hide the selected graphics layers. The graphics layers that are hidden will be invisible in the application window.

Modify

Set the edit status of the selected graphics layer to be TRUE. Users may edit the graphics objects in the layer. Note that only one graphics layer can be edited at a time.

View

View the content of the data file corresponding to the selected graphics layer. MeteoExplorer will launch the default text editor application on user’s system. This operation only makes sense for non-binary data file.

Delete

Delete the selected graphics layers.

Reload

Re-read and re-analyze the data files corresponding to the selected graphics layers. Replace the graphics layers with the new ones. This feature is helpful when the data files are often updated.

Properties

Open the “Graphics layer properties” dialog to let users configure the display properties of the selected graphics layer. Note that only one graphics layer can be configured at a time.

 

3.5.3    Single Layer Operations

The manipulated objects of the above operations are selected graphics layers. Users can select or deselect a layer by clicking the layer title. If a layer is not selected, a single click of the title will make it selected. If a layer is selected, a single click of the title will make it unselected. When a graphics layer is selected, the background of its title text is highlighted in blue.

Besides using the action buttons in graphics layer management window, there is an alternative but more convenient way to toggle to visibility status of a layer: just click the checkbox control next to the graphics layer title. In addition, users can double click the layer title to open the “Graphics layer properties” dialog. In both cases, no selection operation is need at all!

 

Tip: It is more convenient to use the checkbox control next to the graphics layer title to toggle visibility status of a layer, and double click the title to open the “Graphics layer properties” dialog.

 

MeteoExplorer also provides a context menu for operations on a single graphics layer. To bring up this context menu, just right click title of the interested layer (Figure  39).

 

Figure 39: The context menu provides convenient access to commonly used operations on a single graphics layer.

 

There are two more operations for a single graphics layer: “Set layer title as window title” and “Set layer colorbar as window legend”. Both of the operations are related to the canvas layout configuration. Please reference Chapter 5 (page 57) for the description of these two operations.

3.5.4    Graphics Layer Navigation and Animation

Meteorological data are usually organized in five dimensions, apart from 2D horizontal field, other dimensions are:

l  levels;

l  time frames;

l  elements.

A graphics layer is usually a graphic representation of 2D field data of a certain level, time, and element. It is a common operation for users to go back or forward one or more time frames in order to observe the development of atmospheric dynamic. Time navigation differs from animation in that users have to manually change the time frame.

To perform time navigation or animation, users have to select the layers of interested in the first place, then uses the corresponding menu items, toolbar buttons that are describe in Table  3‑4.

For time animation operation, the toolbar buttons will change based on the current state. Before animation starts, the toolbar button is (Windows build) or (Unix/Linux build). During the animation process, the button image is changed to (Windows build) or (Unix/Linux build).

Users can change the time interval between two consecutive time frames during navigation or animation. To do this, select the menu time “View, Time Interval” or its corresponding toolbar button (Figure  310). Four choices are available, among which the option “Automatic” means to use time interval between consecutive time frames in the data set.

 

Figure 310: Users can change the time interval between two consecutive time frames during navigation or animation.

 

Users can also set the animation period between two consecutive time frames by selecting the menu item “Option, Preferences”. This will open the “Preferences” dialog as shown in Figure 312 (page 37).

3.5.5    Differences in Graphics Layer Operations for Different Type of Data Files

As discussed in section 3.5.1 (page 29), the organization structure of the data differs substantially among different type of files. While MICAPS data file usually store the data for a single physics element at a single time instance and level, numerical model output file in general store a lot of physics elements at all time instances and levels. As a result, a single graphics layer operation may have slightly difference meanings for different type of files. Table  39 provides a comparison of what a graphics layer operation can do for MICAPS data file and numerical model output file.

 

Table 39: A comparison of what a graphics layer operation can do for MICAPS data file and numerical model output file.

     Data

 

Operation

MICAPS data file (level one tree node)

Numerical model output file (level one tree node)

Numerical model output file (level two tree node)

Show

Show the selected graphics layers.

Identical to left

Show the selected sub-layers. The selected sub-layers will not be shown if its parent is hidden.

Hide

Hide the selected graphics layers.

Identical to left

Hide the selected sub-layers.

Modify

Set the edit state of the selected graphics layer to TRUE. Users may edit the graphics objects in the layer.

Invalid operation

Invalid operation

View

Open data file corresponding to the selected graphics layer.

Invalid operation

Invalid operation

Remove

Remove the selected graphics layers.

Remove the selected graphics layers along with associated sub-layers

Remove the selected sub-layers. If all sub-layers of a graphics layer are removed, this parent layer is removed as well.

Reload

Refresh the graphics layer by re-loading and analyzing its data file

Identical to left

Invalid operation

Properties

Open the “Graphics layer properties” dialog to let users configure the display properties of the selected graphics layer.

Open the “Universal Model” dialog to let users add a new graphics layer of the physics element in the data set.

Open the “Graphics layer properties” dialog to let users configure the display properties of the selected sub-layer.

Navigate in time

Read and analyze the data file contains the element in the adjacent time instance of the element of the selected graphics layer. The data files should be stored in the same folder and named by time information.

Identical to left

Extract and analyze the data of the element in the adjacent time instance to the element of the selected graphics layer.

Navigate in level

Read and analyze the data file contains the element in the adjacent level of the element of the selected graphics layer. The data files should be stored in the same folder and named by level information.

Identical to left

Extract and analyze the data of the element in the adjacent level to the element of the selected graphics layer.

 

3.6     Thumbnail View

There are two view modes in MeteoExplorer, overlaid view and thumbnail view. In overlaid view for example Figure  613 on page 83, all graphics layers are drawn one over another, in the order of their creation time. In thumbnail view, thumbnail images of all visible graphics layers are drawn one besides another. So the thumbnail view gives users a quick glance of all visible graphics layers. Figure  311 offers an illustration of thumbnail view of six graphics layers.

To toggle between the two views, users may select the menu item “View, Thumbnail View” or corresponding toolbar button  (Windows build) or  (Unix/Linux build). Note that hidden layers will not be shown in thumbnail view. For a graphics layer created from a numerical model data file (see Chapter 6) that consists of multiple sub-layers, a thumbnail image is created for each sub-layer.

 

Figure 311: The thumbnail view of six graphics layers.

 

3.7     Status bar

Except MeteoExplorer is in full-screen mode or thumbnail view mode, the screen coordinate and geographical position corresponding to the mouse pointer position is shown on status bar.

3.8     User Preferences

MeteoExplorer provides a number of options to let users customize the application’s behavior. To configure these options, one should select the “Option, Preference” menu item to open the “Preferences” dialog (Figure 312).

For now MeteoExplorer provides seven options:

l  Render graphics with hardware acceleration;

l  Adjust screen contents based on map scale;

l  Smooth linestrip when drawing synoptic chart;

l  Show graphics layer title in canvas;

l  Animation period;

l  User interface language;

l  Data source directory.

3.8.1    Switch between software and hardware rendering

MeteoExplorer has incorporated a multifunctional graphics rendering engine that is able to switch between hardware acceleration rendering and software rendering[1]. This innovative graphics rendering engine is our answer to the increasing demand on graphics output capabilities from atmospheric science operations and research. First of all, the hardware acceleration rendering technique provides high rendering performance and fluid user experience, both of which improve user’s productivity. Second, software rendering is the key to high-quality vector graphics output. Third, software rendering can serve as a backup solution when user has incompatibility issues in her computer system. For example, when a user remotely logs into her PC, MeteoExplorer can automatically switch to software rendering mode. This is a common practice employed by other commercial software such as Microsoft WordInternet Explorer.

Hardware acceleration rendering is turned on by default in MeteoExplorer. to toggle between the two rendering modes, check or uncheck the “Render graphics with hardware acceleration” control as shown in Figure 312.

 

Figure 312: MeteoExplorer provides a number of options to let users customize the application’s behavior.

 

3.8.2    Adjust screen contents based on map scale

The second option is to adjust the count of graphics objects rendered on the screen based on the current map scale. This option is turned on by default. The motivation behind this option is that some meteorological data distribute densely and irregularly inside certain geographic range. A typical set of examples of such data include high-resolution gridded field, wind field, rainfall field, surface plot data, and city forecast data. If all the graphics objects are rendered at once, there will be a couple of serious issues:

First, rendering huge amount of data leads to poor app performance;

Second, when map proportional scale is large, the graphics objects representing the data are cluttered and users may not have a clear view of the data.

A solution to the issue is to adjust the rendering content based on the current proportional scale of the map. The idea is to draw more (less respectively) graphics objects at the map scale decreases (increases respectively).

As an example, let us take a look at Figure  313. In this figure, the 24-hour valid range precipitation field forecasted by ECWMF on January 1, 2013 is shown. Here the map scale is 1000 kilometers and consecutive grid points are shown with a distance of 2.5 degrees.

 

Figure 313: The rendered result of the 24-hour valid range precipitation field forecasted by ECWMF. Here the map scale is 1000 kilometers and consecutive grid points are shown with a distance of 2.5 degrees.

 

When the user zooms in the map to the extent that the map scale is 100 kilometers, consecutive grid points are shown with a distance of 0.5 degrees (Figure  314).

Figure 314: When the map scale is 100 kilometers, consecutive grid points are shown with a distance of 0.5 degrees.

 

The point is the density of screen contents are adjusted at a relatively reasonable level based on the map scale. Let us see a comparison to justify the point. Figure  315 shows a surface plot data when the “Adjust screen content with map scale” option is turned on. Users are encouraged to compare this figure with Figure  71 on page 85. It can be seen from the comparison that dynamic content adjustment can not only enhance rendering performance, but improve readability as well.

 

Figure 315The rendered result of a surface plot data when the “Adjust screen content with map scale” option is turned on.

 

3.8.3    Smooth line strip when drawing synoptic chart

MeteoExplorer provides an interactive environment for users to draw the predefined symbols and geometric shapes. The way a user draws a line strip is to draw a number of anchor points that determine the shape of the line strip. In implementation, MeteoExplorer calculates the line strip based on the cubic spline interpolation of the polygonal line linking the anchor points.

When a user draws a line strip by consecutively plotting a number of anchor points, MeteoExplorer can provide a preview of the line strip by drawing the spline interpolated line from the polygonal line. To turn on this feature, user should select the “Smooth linestrip when drawing synoptic chart” checkbox control. Figure  316 shows spline interpolated line while the user plots a line strip. Users may disable this feature by deselect this control. To give a comparison, Figure  317 shows polygonal line linking the same anchor points used in Figure  316.

 

For a detailed description on how to plot synoptic chart in MeteoExplorer, please reference Chapter 15 on page 141.

 

Figure 316: When the “Smooth linestrip when drawing synoptic chart” feature is turned on, MeteoExplorer shows the spline interpolated line from the polygonal line linking the anchor points.

 

Figure 317When the “Smooth linestrip when drawing synoptic chart” feature is turned off, MeteoExplorer just shows the polygonal line linking the anchor points.

 

3.8.4    Switch user interface language

MeteoExplorer provide two user interface (UI) languages: English and Simplified Chinese. Users may select the language of their favorite using the “Preferences” dialog without quit the application[2]. Under the hood, MeteoExplorer chooses one of the two languages on its startup process by detecting the first language used in user’s operating system.

 

 


Chapter 4           GIS functionalities

This chapter introduces the basic geographic information system (GIS) features provided by MeteoExplorer.

4.1     Cartographic Projection Settings

MeteoExplorer supports a number of commonly used cartographic projections:

l  Lambert conic conformal

l  Mercator

l  Polar Stereographic of north pole

l  Polar Stereographic of south pole

l  Equidistant Cylindrical

l  Cylindrical Equal Area

l  Orthographic

 

Each projection has its own parameters, among which longitude and latitude of projection are shared by all projections. Table 41 summarizes the definitions of projection longitude and latitude of all supported projections in MeteoExplorer.

 

Table 41: Summarization the definitions of projection longitude and latitude of all supported projections in MeteoExplorer.

Projection

Projection Longitude

Projection Latitude

Lambert conic conformal

Longitude of natural origin

Latitude of natural origin

Mercator

Longitude of natural origin

Latitude of first standard parallel

Polar Stereographic of north pole

Longitude of natural origin

Latitude of natural origin

Polar Stereographic of south pole

Longitude of natural origin

Latitude of natural origin

Equidistant Cylindrical

Longitude of projection center

Latitude of true scale

Cylindrical Equal Area

Central Meridian

Standard Parallel

Orthographic

Longitude of projection center

Latitude of projection center

 

 

Figure 4 SEQ \* ARABIC \s 1 1: User can configure map and projection settings using MeteoExplorer‘s “Map and Projection” dialog.

 

To configure projection settings, please select the menu item “OptionProjection and Map” to open the “Projection and Map” dialog as shown in Figure  4‑1. Users may choose a projection type via the “Projection Type” combobox, and set projection center parameters in the “Projection Longitude” and “Projection Latitude” edit box.

During its launch process, MeteoExplorer loads projection settings of last session from its configuration file. If the configuration file is not available, it will automatically detect geographic location information on user’s system and load pre-defined projection settings based on the location. For example, if a user’s system location is set as “United States”, then the pre-defined projection settings with projection type being Lambert, and the projection center being (90W, 30N) is loaded. Figure  42 shows the re-projected map when the projection center is changed to (80W, 30N). Figure  43 shows the re-projected map when the projection is changed to Mercator and (longitude, latitude) is changed to (110E, 40N).

Figure 42the re-projected map when the projection (longitude, latitude) is changed to (80W, 30N).

 

Figure 43: the re-projected map when the projection is changed to Mercator and (longitude, latitude) is changed to (110E, 40N).

 

4.2     Base Map Settings

4.2.1    Theme

MeteoExplorer provides three pre-defined theme:

l  Operation. In the operation theme (Figure  44), the background is black and the land and ocean is not distinguished. The operation theme has its merit of offering sharp contrast between the graphics objects and the background, therefore fits for the case when large volume of data are rendered.

Figure 44: In the operation theme, the background is black and the land and ocean is not distinguished. The operation theme fits for the case when large volume of data is rendered.

 

l  Publishing: in the “Publishing” theme as shown in Figure  45, the background is white and the land and ocean is not distinguished. All graphics objects are drawn either in black or in gray-scale. This theme is suitable for saving the screenshot of application window to an image file used for publication or presentation.

Figure 45: In the “Publishing” theme, the background is white and the land and ocean is not distinguished. This theme is suitable for saving the screenshot of the application window to an image file, and using the file for publication or presentation.

 

l  Modern: The “Modern” theme is the default theme of MeteoExplorer. As shown in Figure  46, the ocean is drawn in light blue and the land is drawn in white. This color scheme is similar to some popular map applications such as Bing Map or Google Map.

Figure 46The “Modern” theme is the default theme of MeteoExplorer. In this theme, the ocean is drawn in light blue and the land is drawn in white.

 

To change the theme, please use the “Theme” combobox in the “Projection and Map” dialog.

4.2.2    Country and Region

MeteoExplorer provides pre-defined map and projection settings for 79 countries and regions in the world. They are the global, Algeria, Antarctica, Argentina, Australia, Austria, Bahrain, Belgium, Brazil, Bulgaria, Canada, Chile, China, Colombia, Costa Rica, Croatia, Cyprus, Czech Republic, Denmark, Egypt, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, India, Indonesia, Iraq, Ireland, Israel, Italy, Japan, Jordan, Korea, Democratic People’s Republic of, Korea, Republic of, Kuwait, Latvia, Lebanon, Liechtenstein, Lithuania, Luxembourg, Malaysia, Malta, Mauritania, Mexico, Mongolia, Morocco, Netherlands, New Zealand, Norway, Oman, Peru, Philippines, Poland, Portugal, Qatar, Romania, Russia Federation, Saudi Arabia, Serbia, Singapore, Slovakia, Slovenia, South Africa, Spain, Sweden, Switzerland, Thailand, Trinidad and Tobago, Turkey, Ukraine, United Kingdom, United States, Uruguay, Venezuela, Viet Nam, and Yemen. More countries and regions will be added in future releases.

When MeteoExplorer is launched, the country and region will be set based on the location settings in user’s system. To change to another country or region, use the “Country and Region” combobox in the “Map and Projection” dialog. Figure 47 shows the rendered map when the user selects “World”.

 

Figure 47: The rendered map when the user selects “World” from the “Country” combo-box control in the “Projection and Map” dialog.

 

4.2.3    Topology Terrain

MeteoExplorer represents the world topology terrain height using a pre-configured color scheme as shown in Figure  48.

The topology terrain is not shown by default in MeteoExplorer. To show topology terrain, select the “Show Terrain” check box in the “Projection and Map” dialog.

Figure 48: The topology terrain shown in MeteoExplorer.

 

4.2.4    Single State/Province Display and Shading

This feature of state/province shading is meant to draw the states/provinces of a country in different colors. Figure  49 shows the result of rendering provinces of Canada. The option is turned off by default. To turn it on, users can select the “Shade Province” checkbox in the “Projection and Map” dialog.

Users can also choose to show only one state/province of a country. To do this, select the province of interested from the “Province” combo-box control. Figure  410 shows the result of show only British Columbia province of Canada. For this time, the show-only-one-state feature is applicable to eleven countries: Australia, Brazil, Canada, China, France, Germany, Italy, Japan, Spain, Great Britain, and United States. More countries and regions will be added in future releases.

 

 

Figure 49: The rendered map when the “Shade Province” is selected.

 

Figure 410: The rendered map when only British Columbia province of Canada is selected.

 

4.2.5    Drawing Graphics inside a Region

Meteorological scientists and professionals often require that the graphics objects are drawn inside a specified region, such as the country or state border. This feature is available in MeteoExplorer and disabled by default. To turn on this feature, select the “Draw Graphics in Your Country” checkbox in the “Map and Projection” dialog. The mask region that defines the graphics is specified in “Country” control. Figure  411 shows the shaded isolines of sea level pressure field on July 28, 2012. All the graphics objects are drawn inside the country border of the United States.

 

Figure 411: The shaded isolines of sea level pressure field. All the graphics objects are drawn inside the country border of the United States.

 

Figure  412 is another demonstration illustrating the feature. In this case, the same sea level pressure field is drawn inside Alaska of the United States.

Figure 412: The sea level pressure field is drawn inside the Alaska state of the United States.

 

4.2.6    Show South China Sea

As shown in Figure  413, when the user selects “Show South Sea” checkbox in the “Map and Projection” dialog, an image of South China Sea is drawn at the bottom corner of the application window. This option is only enabled when users choose China is the “Country” combo-box.

Figure 413: When the user selects “Show South Sea” checkbox in the “Map and Projection” dialog, an image of South China Sea is drawn at the bottom corner of the application window.

 

4.2.7    World Administrative Areas, Map Scale, and Grid Lines

Apart the features described in the previous sections, the remaining features are all self-explanatory. Figure  414 shows map of Japan when “Show County” option is selected and “Show Grids” option is deselected. Figure 415 shows map of Europe when “Show World Border” option is selected.

Figure 414: The map of Japan when “Show County” option is selected.

 

Figure 415: The map of Europe when “Show World Border” option is selected.

 


Chapter 5           Page Layout

In meteorological operation and atmospheric science research, users often need to customize contents rendered in the application window. The rendered contents include all kinds of graphics elements such as the graphics objects organized with layers, titles, legends, insets, and so on. The customization usually involves adjustment of position and size of the graphics elements. The page layout refers to the organization of position and size of all the graphic elements rendered inside the application window. MeteoExplorer provides the basic layout support. In short it provides two predefined layout views: browse view and image export view, and offers the “page layout settings” dialog to allow user perform customizations.

5.1     Page Layout Design

The layout functionality is not implemented in MeteoExplorer 1.2 release, in which the base map takes the whole screen estate. Some graphics elements like legend, inset are overlaid on top of the base map, whereas the other elements like title do not have their own estate. As a result, the graphics rendering quality is rather limited and does not satisfy users’ requirements.

Nonetheless, the classic view has its own advantage in that it provides larger visual content and therefore gives users more information. It is preferable in the case when users just browse the data. So we call this view as browse view.

 

Figure 51: The position and size of primary graphics elements in image export view.

 

When the user wants to export the screen content to an image file or copy it to the system clipboard, it is a common practice that the rendered graphics objects should be restricted inside a region (we call it canvas in MeteoExplorer) and other elements like title, legend should be added to the screen. We call this layout view as image export view. In all MeteoExplorer provides two views: the classic browse view and new image export view. Figure  51 illustrates the default position and size of primary graphics elements in image export view.

 

In the default design of image export view as shown in Figure  51, the title region is in the top part of the page, and the legend region is near the right edge. The canvas region locates in the center of the page and takes most of the screen estate. To the left (bottom respectively) of the canvas region, there locates the ordinate text region (the abscissa text region respectively). The list below summarizes the functionality of each region:

l  Title Region: the title is shown in this region. MeteoExplorer provides two titles: primary title and secondary title. Users can set the contents of the titles.

l  Legend Region: the region where the legends are drawn. Typical legend examples include the color bar of shaded contour, the color bar of satellite image texture, and symbol description of synoptic chart.

l  Canvas Region: This is the region in which all graphics objects are drawn. In browse view, the canvas is as large as the whole screen. In image export view however, the canvas is reduced to make up room for other graphics elements.

l  Ordinate Text Region: the description text of ordinate is shown in this region. When the map is drawn in the canvas, the latitude line values are often used as text.

l  Abscissa Text Region: the description text of abscissa is shown in this region. When the map is drawn in the canvas, the longitude line (Meridian) values are often used as text.

 

It should be noted that the layout illustrated in Figure  51 is just the default arrangement provided by MeteoExplorer. Users can adjust the position and size of all the five regions at their will. Except for the abscissa and ordinate region, any two regions can intersect with or included by one another.

5.2     Select Page Layout View

As described in the previous section, MeteoExplorer provides two layout view' ;%邎Z抙8LE' ;%邎Z抙xport view. The default layout of MeteoExplorer is the browse view. To switch between the two views, one may select the menu item “View, Layout” or the corresponding toolbar button as shown in Figure  52.

 

Figure 52: To switch between the two views, one may select the menu item “View, Layout” or the corresponding toolbar button.

 

Figure  53 shows the rendering results of the graphics of Figure  613 (page 83) in image export view. As shown in the figure, in image export view, the rendering of all graphics objects is restricted inside the canvas region. The map grid line values are used as axis description text.

Figure 53: In image export view, the rendering of all graphics objects is restricted inside the canvas region.

 

5.3     Set Title and Legend with Information of a Graphics Layer

It can be seen in Figure  53 that MeteoExplorer does not add title and legend to the page when the user switches to the image export view. Instead, it provides two ways to allow users to add title and legend manually. The first approach is to add these graphics elements using the “Page Layout Settings” dialog, which will be introduced in section 5.4. The second approach is to set title and legend using the information of graphics layers.

In MeteoExplorer, every graphics layer is represented by a title as can be seen in Figure 38 on page 31). MeteoExplorer provides a feature to let the user use the graphics layer title as the page title. To do this, one first right-clicks a graphic layer whose title will be used as page title in the “Graphics Layer” window. This will bring up a context menu (Figure  54). Choose the menu item named “Use layer title as window title“.

 

Figure 54: Right-clicks a graphic layer whose title will be used as page title in the “Graphics Layer” window. This will bring up a context menu. Choose the corresponding menu item to use the graphics layer title (legend respectively) as page title (legend respectively).

 

The same procedure can be used to set the page legend with graphics layer legend. In this case, one chooses “Use layer colorbar as window legend” from the context menu. An exception is that a graphics layer may not have a legend like contour color bar. In this case, the operation is invalid and no legend will be added to the page. Figure  55 illustrates an example in which the graphics layer title (legend respectively) is used as the page title (legend respectively).

 

An advantage of using the graphics layer title (legend respectively) as the page title (legend respectively) is that the latter will be changed accordingly with the former. For example, when the user navigates or animates the graphics layer, the page title and legend will also be updated. This automatic update frees the user from the trouble to manually change the page title and legend during navigation.

Figure 55: An example that the graphics layer title (legend respectively) is used as the page title (legend respectively).

 

5.4     Layout Setup

To open the “Page Layout Settings” dialog (Figure  56, Figure  58, and Figure  59), all one has to do is to select the “Options, Page Layout” menu item. The controls in the “Page Layout Settings” dialog are organized into three tabs that correspond to title, canvas, and legend respectively. In each tab, the controls in upper part of the dialog are used for layout customization. At lower part of the dialog, a preview control is provided to give a live visual indication of the position and size of title, canvas, and legend region.

5.4.1    Preview

As can be seen in Figure  56, there is a preview region in the lower part of the “Page Layout Settings” dialog. In the preview region, a couple of rectangles are used to represent the application window, title region, canvas region, and legend region respectively. Except for the largest rectangle that represents the application window[3], the position and size of the other rectangles will change in accordance with the position and size of the corresponding regions. In addition, when the user changes the tab, the corresponding rectangle of the region will be filled with gray color. Take Figure  56 for example, the title region is filled in gray as the user switches to the title tab and changes title settings in the upper part of the dialog. This feature is designed to give users a visual indication as to which region settings are modified.

5.4.2    Title

In “Page Layout Settings” dialog, the controls are grouped into three pages: title page, canvas page, and legend page. When the “Page Layout Settings” dialog is opened for the first time, the title page is displayed and the other two are hidden, as shown in Figure  56. In the title page, users can change the “Top Margin” and “Left Margin” control values to adjust the position of title region, and modify the “Height” and “Width” control values to increase or decrease the title region size. Note that the unit of all these four controls is pixels. If you choose to use the graphics layer title as the page title, please selected the checkbox “Use the Graphics Layer Title as Page Title”. Otherwise, deselect this control to make “Primary Title” and “Secondary Title” control enabled, and then enter the title contents.

 

Figure 56: In “Page Layout Settings” dialog, the controls are grouped into three tabs: title tab, canvas tab, and legend tab. Users can change the position and size of the title, canvas, and legend region using these controls.

 

When the user adjusts the position and size of the tile region, the corresponding rectangle in the preview section will be updated accordingly.

Figure  57 gives an example of adding primary title and secondary title to the page shown in Figure  55.

 

Figure 57: Users can opt to add primary and secondary title content manually instead of use graphics layer title.

 

5.4.3    Canvas

As described in the previous section, the canvas page inside the “Page Layout Settings” dialog is not displayed when the dialog is opened for the first time. However, users can switch to the canvas page by click the canvas tab.

In the canvas page of the dialog as shown in Figure  58, users can change the position and size of the canvas region, choose to use the map grid line values as axis description text, or alternatively enter the abscissa and ordinate text manually. When the user makes the modification of the position and size of the canvas region, the corresponding rectangle in the preview section will be updated accordingly.

 

Figure 58: In the canvas page of the dialog, users can change the position and size of the canvas region, choose to use the map grid line values as axis text description, or enter the abscissa and ordinate text manually.

 

5.4.4    Legend

In the legend page of the “Page Layout Settings” dialog as shown in Figure  59, users can change the position and size of the legend region, select legend style, and specify the legend unit. When the user makes the modification of the position and size of the legend region, the corresponding rectangle in the preview section will be updated accordingly.

MeteoExplorer provides five legend styles:

l  Horizontal bar with square endings

l  Horizontal bar with triangle endings

l  Vertical bar with square endings

l  Vertical bar with triangle endings

l  Blocks arranged in vertical direction

 

Figure 59: In the legend page of the dialog, users can change the position and size of the legend region, select legend style, and enter the legend unit.

 

The legend style in Figure  55 is “Vertical bar with triangle endings” and that in Figure  57 is “Vertical bar with square endings”. Figure  510 shows the shaded contour of objective analysis of a rainfall field. The legend style in the figure is “Blocks arranged in vertical direction”.

Figure 510: The legend style in the figure is “Blocks arranged in vertical direction”.

 

 


Chapter 6           Analysis and Visualization of Numerical Model Data

MeteoExplorer supports several popular data formats used in atmospheric science field, including WMO’s GRIB1 and GRIB2, GrADS, HDF, and NetCDF. These data formats have something in common in that data are organized in five-dimension: physics element, time, altitude or pressure in vertical direction, latitude in the direction of meridian and longitude in the direction of equator. Correspondingly, MeteoExplorer proposes a data structure call “universal model data” to represent these five-dimensional data. The advantages of the universal model data structure are:

l  The universal model data structure is also organized in five dimensions, and is optimized for common operations like insertion, removal, and search.

l  The universal model data structure is designed to be flexible in order to represent as many data formats as possible. It has manages to describe some major data formats including GRIB1, GRIB2, NetCD, and GrADS under its paradigm, and thus provide a universal interface for display, analysis and so on that can be used by high modules.

6.1     WMO GRIB1/GRIB2 Data Visualization

To open a WMO GRIB1/GRIB2 data file, the user may select the menu item “File, Open”, or click the toolbar button , or use the shortcut key “Ctrl+O” to open the file picker dialog. And then select the data file in the dialog. User may also drag and drop the data file from file manager into MeteoExporer window.

 

Tip: To open a file in MeteoExplorer, an alternative and more convenient way is to drag and drop the file from file manager into MeteoExporer window.

 

Let us demonstrate how to analyze and display a GRIB1/GRIB2 data file using a NCEP GFS data file on January 4, 2012 (the file name is GFS_Global_2p5deg_20120104_0000.grib2).

After the user opens the file, MeteoExplorer will first attempt to read the content of the file and represent the data with universal model data structure. It then will extract the data of the first physics element at its first time instance and first level, and do the isoline analysis or stream line analysis to create a new graphics layer, which will be displayed in the application window. As shown in Figure  6‑1, MeteoExplorer does an isoline analysis of the geopotential height element at 10hPa level to create a graphics layer and show it in the application window.

 

Figure 61: MeteoExplorer extracts the data of the first physics element at its first time instance and first level, and does the isoline analysis or stream line analysis to create a new graphics layer, which will be displayed in the application window.

 

6.1.1    Universal Model Options Dialog

The first graphics layer created by MeteoExplorer when processing a GRIB1/GRIB2 data file may not be the graphics that users are interested. It is there just to show a successful read of the file. To create the graphics of interested, users have to do necessary operations using the “Universal Model Options” dialog (Figure  62). To bring up this dialog, the user may in the “Graphics Layer” window (for example Figure  38 on page 31) select the top-level layer and then click the “Properties” button on the right, or double-click the top-level layer.

 

The layout of the “Universal Model Options” dialog is plain. On the left column there is a list view control that lists all the physics elements in the data. Each item in the list contains the information of a physics element: name, unit, and level. Take the selected item “Geopotential height [10gpm] @ Isobaric” shown in Figure  62 for instance. The item indicates that the name of physics element is Geopotential height, unit is 10gpm, and surface level is isobaric. The order of the items in the list view is same as the order of physics elements stored in the GRIB data file.

All the elements are grouped based on their dimension. A two-dimensional (2D) element means corresponding data contains just a horizontal field of one time frame and one level. A three-dimensional (3D) element means the corresponding data contains horizontal fields of multiple levels but only one time frame. A four-dimensional (4D) element means the corresponding data contains horizontal fields of multiple levels, at multiple time frames.

 

Figure 62: The layout of the “Universal Model Options” dialog.

 

Besides the items (colored in blue) corresponding to the elements stored in the data file, additional items (colored in pink) that represent the derived physics elements that are calculated from the elements in the data are also listed. Take the item “specific humidity @ Isobaric” for example, the physics element specific humidity is not the elements stored in the data, but it can be calculated from temperature and pressure whose data are stored in the data.

For now MeteoExplorer supports the computation of the following physics elements:

l  Difference between temperature and dew-point temperature;

l  Specific humidity;

l  Potential temperature;

l  Pseudo-equivalent potential temperature;

l  Isotachs;

l  Wind;

l  Temperature advective;

l  Divergence;

l  Relative vorticity;

l  Vorticity advective;

l  Water-vapor flux;

l  Divergence of water-vapor flux;

l  Potential vorticity;

l  Isentropic potential vorticity;

l  Geopotential height at potential vorticity surface;

l  Temperature difference between 850hPa and 500hPa isobaric layer.

 

When an item from the list view on the left is selected, its time and level information will be obtained by MeteoExplorer and listed in the “All Times” and “All Levels” list view control respectively on the right.

6.1.2    Isoline Analysis of Gridded Field

After you have become familiar with the “Universal Model Options” dialog, it is time to create a graphics layer for the physics elements you are interested. The first step is to select a physics element from list view control on the left. After the selection, the time and level information of the selected element will be respectively listed in the “All Times” and “All Levels” list view control on the right. Select the time instances and levels from the controls. Note that only one physics element can be selected at a time, but users can select multiple time instances and levels by clicking the items while holding the Ctrl key. The selected items will be highlighted in dark blue. Figure  6‑3 illustrates that the user has selected the derived physics element “Geopotential height at PV surface”, with the time 2012-01-12_12:00:00 and level of 1.5 PV unit.

Figure 63After the selection of physics element, time instances and levels, users can click the “Create Graphics” button to generate an isoline representation of the data.

 

After the selection of physics element, time instances and levels, users can click the “Create Graphics Layer” button to start the isoline analysis of the gridded field corresponding to the selection. For a successful analysis, the generated isoline graphics layer will be shown in the application window (Figure Figure 64) and its layer title is listed in “Graphics Layers” list view on the right of Figure  6‑3. In Figure Figure 64, the red contour is the isoline representation of the Geopotential height at PV surface of 1.5 PV unit.

Figure 64: For a successful analysis, the generated isoline graphics layer will be shown in the application window.

 

6.1.3    Change Layer Properties

After creating the graphics layers, users often need to change their properties. To do this, the user should turn to the “Graphics Layer Management” window introduced in section 3.5 (page 29). From there the user selects the graphics layer whose display properties are to be modified, and then select the “Properties” button.

In MeteoExplorer, each type of graphics layer corresponds to a specific properties setup dialog. For a contour graphics layer created from gridded field data as shown in Figure Figure 64, it corresponds to the “Isoline Analysis and Display” dialog (Figure  6‑5). For a stream layer as shown in Figure  141 (page 135), it corresponds to the “Stream line analysis and Display” dialog of Figure  142 (page 136).

 

We are discussing the “Isoline Analysis and Display” dialog in this section and leave the discussion of the “Stream line analysis and Display” dialog in section 6.1.4. As shown in Figure  6‑5, the ”Isoline Analysis and Display” dialog can be divided into two parts: the top part contains the controls for configure isoline analysis settings:

·         Start and End Longitude: the horizontal analysis range of the gridded field. The east hemisphere is 0~180 degrees, and the west hemisphere is 180~360 (-180~0) degrees.

·         Start and End Latitude: the vertical analysis range of the gridded field. The north hemisphere is 0~90 degrees and the south hemisphere is -90~0 degrees.

·         Isoline values in triplet (start, increment, end): users can set the isoline values by specifying start, increment, and end values. This method applies to the case the difference between two consecutive isoline values is a constant.

·         Isoline values in discreate (comma to separate): users can set the isoline values by explicitly specifying them one by one.

·         Shade isoline: Enable or disable isoline shading.

·         Smoothing: smooth the grid field before isoline analysis. The available smoothing methods are: none, 5-point, 9-point, and Gaussian weighted.

 

Figure 65: Users can modify isoline analysis settings in the upper part of “Isoline Analysis and Display” dialog.

 

The bottom part of the “Isoline Analysis and Display” dialog contains controls for users to modify isoline display properties:

·         Line color;

·         Line width;

·         Line style, including solid, dashed, an dotted line;

·         Show Grid-Point Values: show or hide values of grid points.

·         Shading Scheme: let users to choose a shading scheme, available options are none, rainbow, aqua, white-green, white-blue, yellow-red, and white-gray.

 

Figure 66: Users can modify isoline display settings in the lower part of “Isoline Analysis and Display” dialog.

 

Now let us demonstrate the process of configuring isoline analysis and display properties with the example of calculating geopotential height at 1.5 (PV unit) PV surface as illustrated in Figure  63 and Figure Figure 64. Figure  66 shows the four modifications of the use. First, the user reduces the analytic range of the gridded field from global to east-Asia area (70~135E,10~70N). Second, the user decrements the isoline values to 400~900. Third, the isoline shading option is turned on. Fourth, the user changes the line width to 0, hence make the isoline symbols invisible.

 

After the modification, the user may click the “OK” button to make the changes taking into effect. Figure  67 shows the analytic results for the modified settings.

Figure 67: The analytic shaded isolines for the modified isoline analysis and display settings.

 

Tip: The isoline symbols will be invisible if the line width property is changed to 0.

6.1.4    Stream Line Analysis of Wind Field

Wind field is an important reference in synoptic analysis operations. In numerical model output data files however, wind data is stored in its horizontal and vertical component commonly referred to as U and V. As a result, users may have to do an extra step to generate wind field graphics by calculating the wind vector from U and V. Fortunately such a step is not necessary as in MeteoExplorer as the application provides a convenient way to do this.

Figure 68: To create a graphics layer for wind field, the user should first select the item named “Wind@isobaric” from the “Element” list view on the left, and then select the time instances and levels from the “All Times” and “All Levels” list view respectively. Finally, the user clicks the “Create Graphics Layer” button to start the analysis.

 

The procedures to create a graphical representation for the wind field are similar to those to create a contour representation of the gridded field. One first need bring up the “Universal Model Options” dialog by selecting the top-level layer in “Graphics Layer” dialog and then clicking the “Properties” button on the right.

As shown in Figure  68, the user should first select the item named “Wind@isobaric” from the “Element” list view on the left, and then select the time instances and levels from the “All Times” and “All Levels” list view respectively. Here multiple selection of times and levels are possible. Finally, the user clicks the “Create Graphics Layer” button to start the analysis. The generated wind field graphics layer will be shown in the application window and the layer title will be added to the “Graphics Layer” window as shown in Figure  69.

Figure 69: The generated wind field graphics layer based on the selection in Figure  68 is shown in the application window.

 

To change the display properties of a wind field graphics layer, one can follow the same way used to change the isoline graphics layer. In detail, one should first select the graphics layer in “Graphics Layer” window, and then select the “Properties” button. This operation will open the “Streamline Options” dialog as shown in Figure  610. In the dialog, users can configure all kinds of settings from changing display properties such as output type (including stream line, wind barb, and arrowhead) to creating derived physics field like divergence, vorticity, and isotachs. For a complete discussion of the “Streamline Options” dialog, please refer to Chapter 14 on page 135.

Figure 610: Users can configure wind field graphics layer settings using the “Streamline Options” dialog.

 

6.1.5    Export Analytic Graphics Layers

MeteoExplorer provides a feature to let user save the data of the analytic graphics layers to a disk file in either GrADS or MICAPS encoding format. To do this, users first select the graphics layers to be exported in the “Graphics Layers” list of “Universal Model Options” dialog as shown in Figure  68, then click the “Export Graphics Layer” button. In the “Save As” dialog, enter the file name and click OK.

6.2     GrADS Data Visualization

For data files encoded in GrADS format, MeteoExplorer adopts the same processing method it uses for GRIB1/GRIB2 data files. A GrADS data set often consists of two and more files. One of them is so called control file (with the extention .ctl) that contains a complete description of the binary data as well as instructions on where to find the data and how to read it. The other files are binary data files.

 

To open GrADS data files in MeteoExplorer, one only needs to open the control file (.ctl). Figure 611 shows a GrADS-encoded data file output from the Weather Research and Forecasting Model (WRF) numerical model. Two graphics layers are created. One is the potential temperature at 100hPa pressure level (drawn in red solid line), the other is wind at 700hPa pressure level (drawn in yellow stream lines).

 

Figure 611: MeteoExplorer reads a GrADS-encoded data file output from WRF numerical model. Two graphics layers are created. One is the potential temperature at 100hPa pressure level (drawn in red solid line), the other is wind at 700hPa pressure level (drawn in yellow stream lines).

 

6.3     NetCDF Data Visualization

Compared to the GRIB1/GRIB2 and GrADS data format, the NetCDF enjoys a wider range of usage not just limited to atmospheric science field. Many numerical models such as WRF encode their data files with NetCDF format. Since its birth, NetCDF has introduced three formats. The earliest format is called classic format. The 64-bit offset format was introduced in version 3.6. In release version 4.0, the newest NetCDF4/HDF5 format is introduced. For now MeteoExplorer supports the classic format and the 64-bit offset format. Support of NetCDF4/HDF5 format will be added in the future.

 

The process of creating and configuring properties of graphics layers from a NetCDF data file is the same as that from GRIB or GrADS data files. Figure  612 gives an example of the “Universal Model Options” dialog after MeteoExplorer successfully reads a NetCDF-encoded file output from WRF model. As can be seen from the figure, the tree view on the left lists all the elements stored in the data file.

 

Figure 612: An example of the “Universal Model Options” dialog after MeteoExplorer successfully reads a NetCDF-encoded file output from WRF model. The tree view on the left lists all the elements stored in the data file.

 

As another example of visualizing NetCDF data files, Figure  613 shows the sea level pressure (shaded green), 500hPa height (black lines), and wind in the north American region on October 25, 2012, when hurricane Sandy reached its climax.

Figure 613: MeteoExplorer shows sea level pressure (shaded green), 500hPa height (black lines), and wind in United States on October 25, 2012, when hurricane Sandy reached its climax.

 


Chapter 7           Surface Station Data Analysis and Display

MeteoExplorer supports surface station observation data such as MICAPS type-1 data file. To open a surface observation data file, the user may select the menu item “File, Open”, or click the corresponding toolbar button to open the file picker dialog. And then select the data file in the dialog. User may also drag and drop the data file from file manager into MeteoExporer window. Figure  71 shows that a graphics layer analyzed from the surface observation data is rendered in MeteoExplorer.

 

Figure 71: MeteoExplorer supports analysis and display of surface station observation data.

 

7.1     Configure Display Properties of Elements in Surface Station Data

Since there are usually quite a number of stations in a surface observation data set, and there are dozens of weather elements (pressure, temperature, wind etc.) in one station observation, MeteoExplorer by default only shows three elements: wind velocity and direction, cloud coverage amount, and present weather. On the other hand, if all elements are shown, the content rendered in the window will be too overcrowded.

Despite the default rendering scheme, MeteoExplorer provides users with the ability to show or hide certain weather elements via the “Surface Plot Options” dialog as shown in Figure  72. To open this dialog, one has to first select the graphics layer corresponding to the surface data file in the “Graphics Layer” window, and then select the “Properties” button.

 

Figure 72: In the “Elements Selection” page of the “Surface Plot Options” dialog, users can show or hide, change the color of certain weather elements.

 

There are actually two pages in the “Surface Plot Options” dialog, one is the “Element Selection” page, and the other is “Contour” page, which will be described in details in section 7.2.

In Figure  72, a checkbox control is used to show or hide a weather element. The colored button on the right of the checkbox represents the rendered color of the corresponding weather element rendered in the canvas. Take Figure  72 for example, the color of the button next to the wind checkbox is orange. This indicates the wind symbol is drawn in orange in the application window as shown in Figure  71. Click the colored button will open the color picker dialog as shown in Figure  7‑3. In this dialog, users can change the color by specifying red, green, blue, and opacity component values via either the slide control, or the edit control.

Figure 73: In the color picker dialog, users can change the color by specifying red, green, blue, and opacity component values via either the slide control, or the edit control.

 

Table  71 gives a description of the weather elements shown in Figure  72.

 

Table 71: A description of all the weather elements shown in the “Elements Selection” page of the “Surface Plot Options” dialog.

Control Name

Weather Element

Control Name

Weather Element

Wind

Wind drawn in the form of barbs

High Cloud Form

High cloud form

Temperature

Temperature

Mid Cloud Form

Mid cloud form

Pressure

Sea level pressure

Present Weather

Present weather phenomenon

Total Cloud Amount

Total amount of cloud coverage

3H Pressure Variation

Pressure variation within last 3 hours

Visibility

Visibility

Low Cloud Form

Low cloud form

Past Weather 1

Past weather phenomenon within last 12 hours

PastWeather 2

Past weather phenomenon within last 24 hours

Dew point

Dew point temperature

Low Cloud Amount

Amount of Low cloud coverage

6H Precipitation

Accumulated Precipitation within last 6 hours

Low Cloud Height

Low cloud height

Station

Observatory station

 

 

 

In the “Elements Selection” page of the “Surface Plot Options” dialog, there are two additional checkbox controls left unexplained. They are “Select All” and “Clear All”. Selecting the former will show all the elements in the data set, whereas selecting the latter will hide all the elements. In Figure  77 shows rendered results in which only pressure and wind elements are visible. Figure  79 shows the situation where all elements are hidden.

7.2     Objective Analysis of Elements in Surface Station Data

Objective analysis is one of the most important features in MeteoExplorer. For surface observation data, users can do objective analysis in the “Contour” page of the “Surface Plot Options” dialog as shown in Figure  74.

 

Figure 74: In MeteoExplorer, users can do objective analysis of surface station data in the “Contour” page of the “Surface Plot Options” dialog.

 

The layout of controls in the “Contour” page shown in Figure  74 consists of three parts:

The top part outlined in red is used to for objective analysis. The combo box control “Elements” let users to choose a weather element for objective analysis. For surface station observation data, the candidate elements include sea level pressure, temperature, dew point temperature, precipitation (rainfall), and isotachs. The checkbox “Show Contour” serves two purposes. First, if the selected weather element is not analyzed, check this control and click the “OK” button at the bottom of the dialog will let MeteoExplorer perform objective analysis of the selected element and generate a contour graphics layer representing the analyzed result. Second, if the selected weather element has already been analyzed, check (uncheck respectively) this control will show (hide respectively) contour graphics layer representing the analyzed result in the application window.

The middle part named “Objective Analysis” is outline in blue. It contains controls for changing objective analysis parameters:

l  Algorithm. This combo-box control provides several objective analysis method for users:

n  Cressman analysis;

n  Barnes analysis;

n  Customized Cressman using background model and outlier detection;

n  Optimal Interpolation;

n  Surface Fitting.

l  Background Model. As objective analysis method is an iterative correction method, it needs to initial value to start from. In algorithm implementation, the numerical model forecast field at zero hour forecast time range is used as the initial values for the iteration. MeteoExplorer provides the following options:

n  No Background;

n  China T639 numerical forecast model;

n  ECMWF numerical forecast model;

n  Japan numerical forecast model;

n  NCEP global forecast system (GFS) numerical forecast model;

n  WRF numerical forecast model.

l  Smooth Analytical Field. When the user exports the graphics to an image file, she requests that Isolines of analytical field not only agree well with observatory station data, but are as elegantly smooth as possible. To meet this demand, MetroExplorer implements the ability to smooth the analytic field with cubic B-spline interpolation, and provides this feature as an option. Therefore when the user wants visually elegant isolines and does not mind sacrificing analytic accuracy to some extent, she may select this option.

 

In addition to the above three options, MeteoExplorer provides more options but hide them by default in the “Contour” page of “Surface Plot Options” dialog. To see these additional options, one may click the “More Options” button to open the “Objective Analysis Options” dialog as shown in Figure  75. Below is a description of these options.

·         The three edit controls on the top row of “Longitude Start/Interval/End” and three edit controls on the second row of “Latitude Start/Interval/End” define the geographic range and resolution of analysis field. Here a longitude value between 0~180 degrees represents east hemisphere and a value between 180~360 (or -180~0) represents west hemisphere. A latitude value between 0~90 represents north hemisphere and a value between -90~0 represents south hemisphere.

·           The other controls “Algorithm”, “Background Model”, and “Smooth Analytic Field” are indeed identical to the controls in Figure  74.

 

 

Figure 75: User may need to open “Objective Analysis Options” dialog to see all the options of objective analysis.

 

The bottom part of the page named “Contour Display” (outlined in green in Figure  74) consists of controls for changing contour graphics properties, including color, width, style of contour line, shading color scheme, whether or not to show values at grid point. Again only part of contour display options are shown in this page. For a complete configuration of contour display options, one may click the “More Options” button to open “Contour Analysis and Display” dialog (Figure  76).

The “Contour Analysis and Display” dialog provides all the options for configuring contour graphics layers. The controls in this dialog are divided into two groups. The top part is the “Contour Analysis” group and the bottom part is the “Contour Display” group.

The “Contour Analysis” group contains the following controls:

·         Geographic range for contour analysis. The “Longitude start:end” and “Latitude start:end” controls altogether define the area in which the contours are rendered. By default, contour analysis range is identical to the range of analytic field. That is, the contours are rendered within the range of analytic field. The user may specify a contour analysis range that is no larger than the range of analytic field. Figure  710 gives an illustration in which contour analysis range that is smaller than the range of analytic field.

·         Isoline analysis values. In MeteoExplorer, there are two ways for users to specify the isoline analysis values. The first way is set the isoline values by specifying start, increment, and end values. This method is suitable for the case where the difference between two consecutive isoline values is a constant and the range of isoline values is large. The second way is to set the isoline values by explicitly specifying them one by one. This method is usually used in the case that users are interested only in a small number of isoline values. To choose the first method, please select Isoline values in triplet format (start:interval:end)”, otherwise, select “Isoline values in discreate format (comma to separate)”.

·         Shade isoline. Select this option to shade isolines. Figure  79 gives such an example.

·         Smooth options. It is a common practice to smooth the gridded field before perform isoline analysis in order to obtain a visually pleasing result. In addition, for high resolution gridded data, smoothing the field help to remove the roughness in the analytic isolines. MeteoExplorer provides three smoothing methods: “Five Points”, “Nine Points”, and “Gaussian Weighted”. To select a method, choose a candidate item from the “Smoothing” combo box control.

 

Figure 7