HIRS (High-Resolution Infrared Sounder)

HIRS, the High-resolution Infrared Radiation Sounder, is a 20-channel infrared and visible radiometer that profiled atmospheric temperature and humidity from NOAA POES and EUMETSAT MetOp satellites. It read radiance in carbon dioxide and water vapor absorption bands to retrieve vertical temperature structure feeding numerical weather prediction, and its long record dates to TIROS-N in 1978. HIRS is an atmospheric sounder, not an ocean sensor, though its infrared window channels also yield sea surface temperature. It was retired with the POES line as the hyperspectral IASI sounder on MetOp took over; the final HIRS flew on MetOp-A.