Cross-calibration of HIRS aboard NOAA satellites using IASI

Abstract

The 30 years of observations from High-Resolution Infrared Radiation Sounder (HIRS) aboard NOAA series of satellites have been widely used in numerical weather prediction and climate studies. However, there are significant discrepancies in the HIRS measurements between different satellites. The HIRS data from NOAA satellites series need to be recalibrated to establish an accurate and consistent temporal series before it can be used for climate changing detection. To ensure the consistency and reduce the uncertainties for the climate studies of clouds using NOAA HIRS data, this study explores the spectral calibration of longwave CO2 channels for the HIRS on board of NOAA series of satellites using the hyper-spectral IASI radiance measurements from MetOp satellite as reference. The HIRS measurements from each NOAA satellite are compared with the recalibrated HIRS measurements from the successive satellite at Simultaneous-Nadir-Overpass (SNO) locations. For the satellites after NOAA 15, the comparison between the HIRS measurements and the matched IASI measurements at SNO locations is also displayed. A preliminary analysis of the intersatellite biases is performed to quantify the spectral causes of the biases for HIRS channels 4. By removing these biases, our method shows the potential to recalibrate the HIRS on board of the NOAA series of satellites and make the HIRS measurements traceable to the IASI measurements with improved spectral calibration.