Section: 3.2.16 Cross Boundary Subset of Grid Coverage Data

3.2.16 Cross Boundary Subset of Grid Coverage Data

This section describes how to make plots from the cross boundary subset of a cyclic rectilinear grid data.

The set of steps involve:

If other displays and data are already loaded, select the Edit→Remove All Displays and Data menu item or the icon in the toolbar to clear them out.
Connecting to a remote data server and loading GFS one degree as grid coverage type data.
- Open the Data Choosers window.
- Click on the Catalogs node in the chooser tree.
- From the catalog selector drop-down, select the Thredds data server catalog:
  If it is not in the list, type it into the selector area and press the Update button. (Cut and Paste tip )
  A tree view of the data catalog will be displayed in the window below the selector.
- Expand the Realtime data from IDD tab, and then the Forecast Model Data tab.
- Select the latest collection for GFS One Degree - Global Coverage entry.
- Specify the data source type to be Grid Coverage(netCDF/GRIB/OPENDAP/GEMPAK) using the Data Source Type drop down menu and then press the Add Source button.
Cross Seam Spatial Subset
- The IDV defualts the type of model data as "Grid files" type. Only the "Grid Coverage" type has the feature of cross seam spatial subset.
- Spatially subset the grid on the Spatial Subset tab of the Data Source Properties or the Field Selector. The Flip map longitude button at the bottom of the panel flips longitudes of a cyclic rectilinear grid from 0/360 to -180/180 (or vice-versa) before performing the cross seam subsetting.
To make a 3D plot of a cross seam subset of GFS one degree data
- In the Fields panel of data parameters that are categorized as 2D and 3D fields, Click on the 3D grid tab () to expand that category list. Select a parameter named "Speed (from u-component_of_wind_isobaric & u-component_of_wind_isobaric)".
- Select "Isosurface" display in the 3D Surface Displays list and click on the Create Display button. Create another Contour Plan View display by selecting that display in the Plan Views Displays list and click on the Create Display button. Both displays are created and shown in the main window.
- For more information on time and spatial subset, see the Data Source Properties page of this User's Guide.

Unidata IDV Workshop for version 6.3 > Accessing and Displaying Data > Working with Gridded Data