Education Center | Photo Gallery

Data Advanced Data Search More Data Discovery & Access Easy-to-use Data Products Data Collections Data Software & Programming Tools Data Submission Data News Centers & Programs Antarctic Glaciological Data Center GLIMS Glacier Database IARC Frozen Ground Data Center International Polar Year Data & Information Service (IPYDIS) NOAA at NSIDC NASA's Distributed Active Archive Center at NSIDC (NSIDC DAAC) Roger G. Barry Resource Office for Cryospheric Studies (ROCS) World Data Center for Glaciology, Boulder Science Scientists Research Projects Publications NSIDC Notes Glaciological Data Series Special Reports Posters & Presentations Annual Reports Education Resources News & Events Press Room NSIDC In the News Data News Events About Expertise Data & Services NSIDC Sponsors Contacts Jobs Related Organizations Support NSIDC

TOVS Path-P IDL Tools Tutorial

Tutorial 1: Displaying general information and statistics about the data files

This section of the tutorial explains how to extract a table of contents for the TOVS Path-P files and explains how to extract a table of statistics for a specific parameter and range of dates. You will learn how to use the following:

• PPP_TOC - Displays a table of contents of TOVS Path-P files
• PPP_STATS - Displays statistics for one parameter and range of dates

PPP_TOC - Displaying a Table of Contents

The first step in browsing the TOVS Path-P data is to display a table of contents using the IDL procedure, PPP_TOC. This procedure has two required arguments:

1. sds_desc: Returns an array of structures that contain metadata pertaining to each HDF Scientific Data Set (SDS) included in the data. Metadata will include the SDS name, a longer descriptive label, the units, and the fill value used for this SDS.
2. dates: Returns an array of dates, one for each daily file included in your TOVS Path-P data directory.

PPP_TOC will traverse the current directory structure, looking for all TOVS Path-P files contained there and will display an informational message that summarizes what it has found. For an example, please see the TOVS Path-P PPP_TOC Example.

The list of parameter names, returned to you in the array sds_desc.name, is the list of strings that will be considered valid input values to all other routines that accept an argument or keyword called SDS_NAME. The list of dates, returned to you in the dates array, can be used (or subsetted for a particular range of dates) in all other routines that accept an argument called DATES.

Note: PPP_TOC splits the parameter information into two groups: those parameters that change over time and are included in each daily file and those parameters that are static and are included only once in the ancillary data file.

Please refer to the Extended Help Documentation for details on the other keywords to PPP_TOC.

PPP_STATS - Displaying statistics for one parameter and range of dates

Now that you know which parameters are included in the TOVS Path-P files, you may want to use PPP_STATS to extract some statistics for a given parameter and range of dates. PPP_STATS has one required argument and a number of keywords for flexibility. The required argument is sds_name, which is a string that you select from the parameter listing you just displayed with PPP_TOC.

PPP_STATS also accepts keywords for a date range (START_DATE and END_DATE) or an array of specific dates (DATES). Any dates entered as keywords in this way can be either integers or strings of the form yyyyddd (4-digit year and 3-digit day of year). Other functions that behave similarly are PPP_ANIMATE, PPP_EXTRACT, and PPP_PLOT, which will be covered later in another section of the tutorial. These keywords are not required arguments, because PPP_STATS can also be used to display statistics for the ancillary parameters which are static data that have no associated dates. For an example, please see the TOVS Path-P PPP_STATS Example.

Please refer to the Extended Help Documentation for details on the other keywords to PPP_STATS.

Next tutorial section