The following section, introduces the user to the MPLOT/UMPLOT interface, by describing how to select and display a two dimensional horizontal dataset from a single file. The mplot98/umplot98 programs are run using the following command
> mplot98 [-nc] [-dc] or umplot98 [-nc][-dc]
By default, the programs will treat data from a non-rotated model dataset [refer to Appendix 1 ] as being cyclical in the x-direction. The -nc option will override this default setting and the cyclical flags will be set to false in both the x and y direction. The -dc option overrides the default option to use a private colour map. The -dc colours will allocate colours to the current colormap currently being used by the hardware. This option may have to be used on workstations which will not allow the allocation of private colourmaps.
At run-time the main window will display the Query Menu. (Figure 2,1).
Figure 2.1 The Query Menu
Three types of query are available (Section 3.3 :Queries). To select a single field from a single file, place the cursor over the Scalar option and click once using the left hand mouse button. The filename text window (figure 2.2), will now be displayed on the screen.
Figure 2.2: The filename text window
If the DATA_DIRPATH environment variable has been set then this will form the prefix for the filename on the input line. To enter data, click once on the input line using the left hand mouse button . Using the keyboard enter the name of the file you wish to open, then click once on the Okay button, which appears on the text input area. Files must be of the NCSA's Hierarchial Data Format ( HDF ). If the file you have requested cannot be opened, or has not been recognised as being HDF, an error dialog box will issue a warning to the user that the file could not be opened.
While information is being read from the file, the following message will appear on the screen. This will stay visible until all required information has been read. Please note, in some cases it may take longer to read the information because of the type of data stored. For example, if using OCCAM archive restart file, the masking fields will be read at this time.
Figure 2.3 File Information Message
If the file has been opened successfully, a menu will appear on the screen listing the datasets in the file (figure 2.4).
Figure 2.4: Dataset Listing Menu
The name, rank, level and orientation of each dataset in the file is listed in the menu. The level and the orientation information may be stored as dataset attributes. If these attributes have not been set in the file, then no text will be set for this option. Using the mouse button, place the cursor over the "FREE SURFACE HT" menu item and click the left hand mouse button. (Please note: the name of the free surface height field may vary depending on the source file you are using). This dataset will now be selected from the file. If you wish to visualise data from a three dimensional dataset, then both an orientation and a level will be needed. (refer to section 3.4 Changing Orientation and 3.5 Change Level). Whilst the requested data is obtained from the dataset, the following message will appear on the screen
Figure 2.5: Data Message Box.
Before the image is drawn , the interface will prompt the user to enter the minimum and maximum limits for the displayed data . The text input window for the data limits is shown in figure 2.6. By default, the limits text input window will display the limits for whole dataset. If you wish to change the limits used, click on the prompt line, and then enter the new data. Click on the Okay button. to continue with the displayed limits.
Figure 2.6: The Limits Text Input
If the minimum value entered is greater than the maximum value or the values are equal , the program will be unable continue. The user will be warned of the error. Otherwise, the data will be plotted as a colour image as shown in figure 2.7.
Figure 2.7: Data displayed from a non-rotated dataset.
The main window is divided into three sections. The top part of the main window displays information about the file.
Variable Name: Name of dataset selected from data file.
Data Type: Displays the HDF file attribute that specifies the type of data in the file. For example, if the an OCCAM archive data file has been opened, then "Modelled" will be displayed in this area. If this attribute has not been set in a file , then this field will be left blank.
Grid:Displays the setting of the FILE_TYPE attribute. For example, if set, and the data stored is from a non-rotated data set, then Non-Rotated will be displayed in this field. If undefined, then this will be left blank.
Query Mode:Specifies current query type e.g Single, Vector or Difference.
The middle section displays the image, and the lower section displays a colour legend, the name of the file and the level that the data was taken from.
Using the mouse button, move the cursor over the image in the window. In the top window, the latitude and longitude ( if an horizontal section ) will be displayed and also the data values for that point. Selection of further actions is carried out through the main menu. The main menu controls the selection of other functions of the MPLOT/UMPLOT program.
Figure 2.8: The Main Menu
The main menu can be selected by clicking the left hand mouse button within the main window.