VIIRS vs. MODIS vs. AVHRR for Fishing

VIIRS and MODIS are the two infrared sensor families Chlorofishy ingests directly, each aboard multiple satellites with slightly different resolutions. AVHRR is an older, separate NOAA instrument line still flying today, but not one of Chlorofishy's current sources, worth knowing about because it shows up in other tools' data credits.

VIIRS

VIIRS (Visible Infrared Imaging Radiometer Suite) flies aboard three satellites Chlorofishy ingests: Suomi-NPP, NOAA-20, and NOAA-21. SST passes run about 2km native resolution; chlorophyll passes run finer, about 750m, but daytime-only, since chlorophyll retrieval needs reflected sunlight. Three separate satellites carrying the same instrument means more chances per day to catch a given region in a clear window. See satellite revisit times.

MODIS

MODIS (Moderate Resolution Imaging Spectroradiometer) flies aboard NASA's Aqua satellite, one of the original instruments behind the modern ocean-color and SST record. Chlorofishy ingests MODIS Aqua for both SST (~1km) and chlorophyll (~1km, daytime-only). Aqua's orbit crosses the equator in early-to-mid afternoon local time, which is why MODIS daytime passes over a given region tend to land at a consistent time of day.

AVHRR: not currently a Chlorofishy source

AVHRR (Advanced Very High Resolution Radiometer) is NOAA's older polar-orbiter SST instrument line, still flying on several operational satellites and still a common input to other ocean data products, including some GHRSST Level 3 SST products, per NASA PO.DAAC's own AVHRR product catalog. Chlorofishy does not ingest AVHRR directly today: our composite's inputs and our raw passes both come from the VIIRS, MODIS, OLCI, and AMSR2 sensors described on data sources. If you see AVHRR credited elsewhere, it's a legitimate, independent sensor family, just not one currently feeding this app.

Quick comparison

For resolution across every layer, including the microwave and composite products, see native resolution, explained. See these sensors live on the SST map. Back to Learn.