Recalibrating HIRS Sensors to Produce a 30 year Record of Radiance Measurements Useful for Cloud and Moisture Trend Analysis

The High resolution Infrared Radiation Sounder (HIRS) has been flown on seventeen satellites from TIROS-N through NOAA-19 and METOP-A and B forming more than a 30-year record. Sensor to sensor radiance calibration differences have been mitigated using high spectral resolution infrared data from the Infrared Atmospheric Sounding Interferometer (IASI) as a reference to adjust spectral response functions in the recent HIRS data (NOAA-15 through NOAA-19). Satellite Nadir Overpasses (SNOs) have been used to intercalibrate the HIRS sensors before IASI (NOAA-9 through NOAA-14). For NOAA-6 through NOAA-8 geostationary sounder data from the Visible Infrared Spin Scan Radiometer (VISSR) Atmospheric Sounder (VAS) are being used to connect HIRS calibrations in the absence of HIRS SNOs. Thirty year trends in high, mid, and low level clouds and moisture are now being reprocessed.