HIRS/4 products
Data from the Advanced Very High Resolution Radiometer (AVHRR) instrument is used, in conjunction with the microwave instruments, to calculate the atmosphere's vertical temperature profile from the Earth's surface to about 40 km (24.85mi) altitude. The data is also used to determine ocean surface temperatures, total atmospheric ozone levels, precipitable water, cloud height and coverage, and surface radiance.
HIRS/4 calibration & validation
In-flight IR calibration of the HIRS/4 is provided by programmed views of two calibration references. A warm reference is realised by an internal warm calibration target thermally coupled to the instrument baseplate. The cold calibration is achieved by a view of the instrument to cold space.
Data from these views provides sensitivity calibrations for each IR channel at 256 second intervals, when commanded.
