A long-term record of hyperspectral infrared radiances may prove to be an extremely important climate record due to the various processes encoded in these radiances. Studies using long-term records of radiances can be much more straightforward to understand given the complexity of the retrieval process and dependence on a-priori data. The AIRS sensor on AQUA is the first long-term hyperspectral sensor, and it has exhibited extremely stable (< 0.01K/year) radiances with high accuracy. However, there are various instrument instabilities that affect the AIRS spectral response functions (frequency calibration, fringing) that severely limit the raw L1b radiances for direct use in science investigations. The IASI spectrometer on METOP, and the CrIS sensor on NPP/NPOESS promise to continue this record , with somewhat different spectral characteristics. We propose to develop corrections to the AIRS radiance products to make them climate quality, and to also develop algorithms to produce a uniform climate data set of radiances that can be intercompared with AIRS, IASI, and CrIS. This work will include extensive inter-calibration of these three sensors (assuming they are all in orbit at the same time). We may also examine various climate subsets (clear only data) and determine if the effects of variable gases (esp. CO2) can be removed (or should be removed) from the hyperspectral radiance record.
