Using Averaging Kernels to Study the Vertical Resolution of the CrIS and IASI Retrieval Products

This work will present results about the use of averaging kernels for the study of the vertical resolution of sounding products retrieved from the Cross-track Infrared Sounder (CrIS) and Infrared Atmospheric Sounding Interferometer (IASI) observations. For this work, the NOAA-Unique Processing System will be used as the retrieval system to process CrIS and IASI observations. The NOAA-Unique Processing System is a heritage algorithm based on the Atmospheric Infrared Sounder (AIRS) Science Team algorithm, designed for deriving environmental data records (EDRs) from the Joint Polar Satellite System (JPSS) satellites. One of the goals of an atmospheric profile retrieval system is to estimate the state of the atmosphere using an optimal set of observations containing independent information content in order to simultaneously minimize the retrieval error and maximize the vertical resolution. CrIS and IASI instruments hold different spectral channels. At nominal resolution, CrIS holds 1305 channels from 3.92 to 15.38 µm, while IASI has 8461 spectral channels ranging from 3.62 to 15.50 µm. The averaging kernel will help us to determine the number of degrees of freedom (or estimate of useful number of independent observations) as well as the vertical resolution of the retrieval when CrIS and IASI observations are applied to the same retrieval system, allowing us to characterize the impact of the spectral channels in the quality of the retrieved atmospheric profiles. This work will help us to diagnose the vertical resolution of retrieved sounding products over different latitudes and seasons, and to support comparisons of retrievals against correlative radiosonde measurements.