Displaying JPSS data from the NODD using Polar2Grid
Joint Polar Satellite System (JPSS) data are now available online as part of the NOAA Open Data Dissemination (NODD) Program; at present, the data are available via Amazon Web Services (with future capabilities planned for Azure and Google). Global Suomi-NPP, NOAA-20 and NOAA-21 data (including Sensor Data Records (SDRs) and Environmental Data Records (EDRs) from ATMS, VIIRS and OMPS — and also geolocation files) are all available for free download. How can you create a display of the imagery, as shown above? The CSPP Software package Polar2Grid (v 3.0, available for download here) produced the image you see above.
After downloading Polar2Grid, you’ll need to determine the times of the data you wish to display; the data on the Cloud are saved off in roughly 90-second intervals. I consulted the SSEC Polar Orbit page (link) to find a (random) orbit from NOAA-21, where the orbit chosen is an ascending pass over Indonesia between 0320 and 0330 UTC on 5 May. The next step is to go to the Amazon Web Service data repository and find the I01 SDRs for the imagery to be created, and the geolocation information. Those webpages are shown below, with the files with data from 0320 to 0330 highlighted in the toggle. Note that the timestamps of the eight I01 and geolocation files are the same: 03:20:13.5, 03:21:37.7, 03:23:03.6, . . . 03:30:11.3. Download these files to a directory on the machine on which Polar2Grid is also installed. Note that these ‘GIMGO’ geolocation files are not terrain-corrected; the AWS site does include a directory (VIIRS-IMG-GEO-TC) that includes terrain-corrected geolocation files (‘GITCO’) that would be appropriate to use in regions of high terrain.
The Polar2Grid calls (remember that the environment variable $POLAR2GRID_HOME must be set) to create the imagery are straightforward:
$POLAR2GRID_HOME/bin/polar2grid.sh -r viirs_sdr -w geotiff -p i01 -f ./Cloud/*I01*.h5
(the ‘GIMGO’ files downloaded are also in that ./Cloud/ directory) reads the viirs_sdr I01 files and creates a geotiff image, and
$POLAR2GRID_HOME/bin/add_coastlines.sh --add-coastlines --add-grid --grid-D 10.0 10.0 --grid-d 10.0 10.0 --grid-text-size 20 noaa21_viirs_i01_20230505_032013_wgs84_fit.tif
adds coastlines and a latitude/longitude grid to the geotiff file created, and creates a png file (shown here at full resolution; VIIRS Image Files at native resolution are very large — this 10-minute one is 6500×7600 pixels! — because they’re at 375-m resolution; note also that the flag --coastlines-resolution f was added to the ./add_coastlines.sh call for the full-resolution image). The reduced-size image above was reduced in size and annotated using ImageMagick.
