Satellite SST is the longest and most mature application of ocean remote sensing. Passive observations are made with infrared (IR) sensors onboard multiple polar-orbiting and geostationary platforms, and microwave sensors onboard polar platforms. The IR sensors have higher spatial (1-4km) and temporal (10-15min, onboard geostationary satellites) resolution, and superior radiometric performance. However, IR sensors cannot "see through cloud", thus typically limiting retrievals to ~20% of the global ocean, whereas microwave sensors may see through clouds (except heavily precipitating) and therefore have higher coverage, but have coarser spatial resolution (~20-50km) and radiometric performance, cannot be used in coastal and marginal ice zone areas, and may be subject to other errors (due to e.g. radio frequency interference, RFI)

NOAA produces several L2 (Level 2) (original swath), L3 (gridded), and L4 (gap-free analysis) SST products in international Group for High-Resolution SST (GHRSST) Data Specifications version 2 (GDS2) and makes them available from NOAA CoastWatch: