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2.4 Cross Boundary Subset
This section describes how to make a cross boundary subset of a cyclic rectilinear grid as a grid coverage type dataset. The set of steps involve:
2.4.0  Connecting to a Remote Server for a grid coverage type data
2.4.1  Cross Boundary Spatial Subsetting
2.4.2  To make a cross boundary 3D plot of GFS one degree data
2.4.0 Connecting to a Remote Server for a grid coverage type data
In the Data Chooser select the Catalogs tab.
images/CatalogChooser1.png

Choose one of the remote Catalogs: such as https://thredds.ucar.edu/thredds/catalog.xml of Unidata's Thredds Data Server for the near real-time model output. A tree view of the catalog will be displayed. Open one, such as the "GFS One Degree - Global Coverage model data (real and near time)", by clicking on one of the tab icons (icon).

Specify the data source type to be Grid Coverage(netCDF/GRIB/OPENDAP/GEMPAK) using the Data Source Type drop down menu. The IDV defualts the type of model data as Grid files(netCDF/GRIB/OPENDAP/GEMPAK). Only the "Grid Coverage" type has the feature of cross boundary spatial subset.

The list of this model's run times appears. Click on "Best Time Series" or "Latest Collection" to select it, and then click on the Add Source button. You have selected the model output to be accessible by the IDV.

2.4.1 Cross Boundary Spatial Subsetting
You can spatially subset the grid on the Spatial Subset tab of the Data Source Properties or the Field Selector. This works similarly to the grid file subset where you can set properties for all fields of the Data Source or override the default property for a particular field on the field selector subset panel. The difference in the Coverage data spatial subset is that the Flip map longitude button at the bottom of the panel will allow user to flip longitudes in a cyclic rectilinear grid from 0/360 to -180/180 (or vice-versa) before performing the cross boundary spatial subset.
images/DataSourceSpatialSubset1.png

For more information on time and spatial subsetting, see the Data Source Properties page of this User's Guide.

2.4.2 To make a cross boundary 3D plot of GFS one degree data
The grid coverage data source that you selected will be shown in the Field Selector window. In the Fields panel are folders of data parameters categorized as 2D and 3D fields. Click on the 3D grid tab (icon) to expand that category, further expand Momentum and Derived tab, click on "Speed (from u-component_of_wind_isobaric & u-component_of_wind_isobaric)" and select "Isosurface" display type, click on the Create Display button to create a wind speed isosurface display. Create another Contour Plan View in the Plan Views Displays list. Both displays will be created and shown in the main window.
images/IsoContours.gif

 


Previous: Plots from Gridded Data Next: Surface Observations - METAR and Synoptic Plots Table of contents Images Frames Unidata's Integrated Data Viewer > Getting Started