Abstract
This study will examine possible relative trends in the radiometric calibrations of AIRS and IASI. The stability of the AIRS calibration in window channels over tropical oceans has been shown by Aumann to be 5 mK/yr or better using 10 years of data. IASI data have been available for five years, and during IASI’s time in operation there have been significant El Niño and La Niña events. Those events introduce additional uncertainty into trend determinations that are more significant for IASI because of its shorter time in operation. When IASI and AIRS are directly compared in a double difference, the El Nino / La Nina effects cancel, allowing for an improved measurement of any instrumental trends in IASI over what can be done using IASI data alone.
Relative Trends of AIRS and IASI Radiometric Calibrations
This study will examine possible relative trends in the radiometric calibrations of AIRS and IASI. The stability of the AIRS calibration in window channels over tropical oceans has been shown by Aumann to be 5 mK/yr or better using 10 years of data. IASI data have been available for five years, and during IASI’s time in operation there have been significant El Niño and La Niña events. Those events introduce additional uncertainty into trend determinations that are more significant for IASI because of its shorter time in operation. When IASI and AIRS are directly compared in a double difference, the El Nino / La Nina effects cancel, allowing for an improved measurement of any instrumental trends in IASI over what can be done using IASI data alone.