This section describes how to make displays using gridded data sets. The steps include:

• Connecting to a Data Source on a Remote Server
• Creating a Plot of 2D Data
• Creating a Plot of 3D Data
• Subsetting Times
• Subsetting Spatially
• Accessing Additional Tutorials

In the Data Explorer window, select the Data Sources tab. On the left side of this tab, select Gridded Data->Remote from the list of available choosers. For more information about the catalog chooser, see Choosing Gridded Data.

Image 1: Data Sources Tab of the Data Explorer

Choose one of the remote Catalogs: such as http://motherlode.ucar.edu:8080/thredds/idv/models.xml for Unidata's catalog of near real-time model output.

A tree view of the catalog will be displayed. Open one, such as the "NCEP Model Data -> Global Forecast System Model -> NCEP GFS CONUS 80 km", by using the tab icons ().

The list of this model's run times appears. Click on one time to select it, and then click the button. You have selected this model run's output to be accessible by McIDAS-V.

The gridded data source that you selected will be shown in the Field Selector tab of the Data Explorer. The Field Selector tab contains folders of data categorized as 2D and 3D fields. Click on the 2D grid tab () to expand that category list. A list of all 2D grid parameters in the data source appears. When one of the fields is selected, the list of applicable displays will be added to the Displays panel.

Image 2: Field Selector Tab of the Data Explorer

Create a Contour Plan View display by selecting that display in the list and clicking on the Create Display button. The display will be created and shown in the Main Display window. The display's Legend should also be shown. You can open the control window by right clicking on the name in the legend and selecting Control Window.

Image 3: Contour Plan View Display in the Main Display Window

In the Field Selector tab of the Data Explorer, click on the 3D grid tab to expand that category. A list of all 3D grid parameters appears. To make a plot, first select a parameter name such as "Geopotential height at isobaric levels".

Display types suitable for this parameter are listed in then Displays panel. Select the Contour Plan View display, and click the Create Display button.

The initial plot is at the lowest level in the data grid, such as 1000 millibars in this example. To shift the level to other levels:

• Right click on the Legend (such as "T Contour Plan View Level 1000") and select Control Window.
• In the Control window, click on the Levels: box to bring up the pop-up menu of native grid levels for the data.
• Select the desired level from the list.

The data in the Main Display window will now be representative of the new level you have selected.

To zoom, pan, or rotate this 3D display, see Zooming, Panning, and Rotating. To toggle on the time animation loop, use the Run/Stop icon in the Time Animation Widget. To remove an existing display, use the File->Remove Display menu of the Layer Controls tab.

McIDAS-V automatically loads data for all times selected in the Layer Controls tab of the Data Explorer, and loads them as displays for an animation loop. Creating several displays may take time. If you only need to see one data time, it is better to only create displays for that time, as McIDAS-V will load in smaller loops of data faster than larger ones.

To make time selections that apply to all data in one data source, double click on the data source name in the Data Sources panel of the Field Selector tab to bring up the Data Source Properties editor. Click on the Times tab to subset the times.

Image 4: Times Tab of the Subset Panel

Initially, all times are selected for display, indicated by the times in this window being grayed out and the Use Default checkbox being checked. To limit the selection to fewer times than all times, first check off the Use Default checkbox, and then select the times you want by clicking on the times (Note: You can select multiple times with the Shift and Ctrl keys). The selected times will be highlighted in blue, and these are the only times that will appear in your loop of data in the Main Display window.

To make time selections for one field, use the Times tab in the lower right panel of the Field Selector tab after you select the field and before you create the display. This will override the default times for the data source selected in the Field Selector tab of the Data Explorer.

You can also spatially subset the grid using the Spatial Subset tab of the Data Source Properties. This works similar to the times subsetting where you can set the property for all fields in the Data Source or override the default for a particular field.

For more help with displaying gridded data, please see the Gridded Data tutorial on the McIDAS-V Documentation webpage.