TOVS Path-P IDL Tools Tutorial

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Example 3: EASE_CONVERT, EASE_INVERSE, PPP_PLOT, and PPP_COMPARE

This Web page provides examples of how to use the following IDL routines for the TOVS Path-P data set:

TOVS Path-P EASE_CONVERT and EASE_INVERSE Example:

To determine the TOVS grid cell that contains the North Pole, for example, call EASE_CONVERT using the following commands:

IDL> status=ease_convert('NPATHP',90.,0.,col,row)
IDL> print,status,col,row

Which should result in output similar to the following:

0 33.0000 33.0000

To perform the reverse operation and find the (latitude,longitude) coordinates of the center of a given grid cell, for example, the cell at column 20 and row 35, use the following commands:

IDL> status=ease_inverse('NPATHP',20,35,lat,lon)
IDL> print,status,lat,lon

Which should result in output similar to the following:

0 78.1185 -81.2538

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TOVS Path-P PPP_PLOT Example:

This example uses PPP_PLOT to get a time series of surface pressures at Point Barrow, Alaska. First, find the (column,row) coordinates for the Point Barrow, Alaska test site at 71.3163452 N, 156.596268 W using the following commands:

IDL> status = ease_convert('NPATHP',71.3163452,-156.596268,col,row)
IDL> print,status,col,row

Which should result in output similar to the following:

0 24.8063 14.0687

Next, run PPP_PLOT on a short series of dates using the following command:


IDL> ppp_plot,'press',col,row,dates=1988001+indgen(9),/verbose,title='Point Barrow Surface Pressure, 1988',/cursor

You should see a window that is similar to the one below:

Plot of Point Barrow, Alaska, Surface Albedo, 1988

When you left- or middle-click the mouse in the plot window, you should see corresponding output with date (mm/dd/yyyy) and data values in your IDL window. Right-click the mouse in the plot window to exit and return to the IDL command line.

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TOVS Path-P PPP_COMPARE Example:

This example uses PPP_COMPARE to create a scatter plot of CLTEMP and CLPRESS:

IDL> ppp_compare,'cltemp','clpress',1988180

In the event that you see a window with a very long title that does not fit in the window, try it again and turn on the interactive cursor this time; but use IDL's keyword inheritance to explicitly set the TITLE keyword in the PLOT call using the following command:

IDL> ppp_compare,'cltemp','clpress',1988180,/cursor,title='Cloud-top Temperature vs. Pressure, 6/29/88'

You should see a window similar to the one below:

Scatter Plot of Cloud-top Temperature vs. Pressure, June 29, 1988

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