Using data from NODD and Polar2Grid to create animations with JPSS data
The presence of three JPSS satellites — Suomi NPP, NOAA-20 and NOAA-21 — allows for animations at high resolution (I01 imagery on VIIRS has 375-m resolution) at even low latitudes. The animation over the island of Guam (at 13.4oN) shows the evolution of clouds between 0246 and 0358 UTC on 17 July 2023. These data were downloaded from the NOAA NODD and processed with Polar2Grid v 3.0 as described here. This requires downloading granules from the VIIRS-I1-SDR directory and geolocation data from the VIIRS-IMG-GEO directory at the NODD websites. Whether or not good coverage is available (and when it happens!) can be shown a day to three in advance at the SSEC Polar Orbit Tracking website, which includes graphics over the western Pacific for Suomi-NPP, NOAA-20 and NOAA-21. Knowing when the data will be available means a timely image can be made. Note that the resolution of the images above has been reduced to 1 km!
Geostationary satellites also show imagery over the same region. Himawari-9 visible (band 3, 0.64 µm) imagery, below, has been processed using Geo2Grid software operating on Himawari-9 HSD files (that, like JPSS data files, are available online). The animation below shows Band 3 imagery over the same domain as above, from 0250-0400 at 10-minute intervals. Whether or not a user needs high spatial resolution (far better with JPSS data, especially in the infrared) or better temporal resolution is a question best answered by the phenomena that are being investigated. If there were a small fire on Guam, for example, JPSS data with a 375-km resolution at 3.74 µm is more likely to detect it than Himawari-9 Band 7 imagery (3.8 µm) with 2-km nadir resolution.
