Let's create a data probe to read out various parameters at different levels.

• If you have not already done so, use the Edit→Remove All Displays menu to remove the displays created in the previous exercise.
• In the Fields panel, expand the 2D grid tab. Select the mean sea level pressure (ETA model reduction) field.
• In the Displays panel, select Color-Shaded Plan View. Expand the Probes tab, then, hold the Ctrl key down and click on Data Probe/Time Series to select both. Click the Create Display button. Once the displays are created, you can minimize the control window for the color shaded display.
• Drag the selector point around in the main window and notice how the readout changes.
• Now, let's look at the difference between Nearest Neighbor and Weighted Average sampling techniques.
  • Use the rubber band zooming feature (Shift+Mouse drag) on the main view window to zoom in over the central United States (centered on Kansas). The blocky pattern you see shows the outline of each grid cell.
  • Bring up the Control Window for the color shaded display and click the Shade Colors check box. Notice how the pattern changes. Return to the blocky pattern by unchecking the Shade Colors checkbox.
  • From the Probe Control window, right click on the Psl_et line and select the Parameter: Psl_et→Copy menu.
  You will now have two entries for this field in the Probe control.
  • Change one of the entries to sample using Weighted Average by clicking in the table row under the Sampling column and selecting that option from the dropdown list.
  • Now move the probe around. Notice how the values in the two rows differ as you move from grid cell to grid cell in the display. Nearest Neighbor sampling will list out the value at the grid point. Weighted Average sampling will list out a weighted average of the values at surrounding grid points.
  
  
• Now, let's add in a 3D field to the list and sample that at different levels.
  • First, return the main display to its unzoomed position.
  • Right click on any row in the table and select the Add→parameter... menu.
  • From the Field Selector, expand the 3D Grid tab and select the temperature field. Click the OK button. You will now see an entry for T in the table in the Probe control window that lists the Level as Probe's. It will also be added to the chart.
  • Move the probe to the north and you will see that in general temperature decreases at the probe's altitude. Move it to the south and you will see that in general temperature increases.
  • Now rotate the display to a south view. Drag the probe up and down and notice how temperature changes with altitude in the atmosphere.
  • Now, let's move the temperature to it's own chart. Right click on the temperature line in the table and select the Parameter T→Chart Properties menu select the same menu from the contrl's View→Parameters menu.
  • In the Chart Name box, type in Temperature. In the Min box, type in -30 and for Max, type in 30 and click OK.
  • Now add two more rows of Temperature to the table by copying the current temperature field.
  • Change the Level of one of the temperature fields to be 850 hPa by clicking in the box for that row under the Level column and selecting that level from the list. Change the Level of another of the temperature fields to be 500 hPa.
  • Now move the probe around and you will get a readout of each of the fields at the specified levels.
  • Change the layout of these two charts by selecting View→Chart→Layout→Horizontal
  
  
  • Start the animation to see how the field values change with time.
  • Stop the animation and remove all displays.

Unidata IDV Workshop for version 6.2u2 > Accessing and Displaying Data > Working with Gridded Data