4.1.4 Probing Gridded Data
The IDV has a variety of data probes that can be used with
gridded data. Probes include value readouts, vertical profiles,
model soundings, time/height cross sections and time series
Let's create a data probe to read out various parameters
at different levels.
Now, let's add in a 3D field to the list and sample that at
- If you have not already done so, use the
menu to remove the displays
created in the previous exercise.
- In the
Fields panel, expand
2D grid tab.
mean sea level pressure (ETA model reduction)
- 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
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
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
You will now have two entries for this field in
the Probe control.
Psl_et line and select
- Change one of the entries to sample using
Weighted Average by clicking in the table row under
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.
- First, return the main display to its unzoomed position.
- Right click on any row in the table and select the
- From the
3D Grid tab and select the
field. Click the
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
- 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
select the same menu from the contrl's
- In the
Chart Name box, type in Temperature.
Min box, type in -60 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
Level column and selecting
that level from the list. Change the
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.
- Start the animation to see how the field values change
- Stop the animation and remove all displays.
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