Using averaging kernels to study the vertical resolution of nucaps temperature and water vapor

Abstract

This work presents an analysis of the vertical resolution of the temperature and water vapor retrieved by the National Oceanic and Atmospheric Administration (NOAA) Unique Combined Atmospheric Processing System (NUCAPS) using averaging kernels as a diagnostic tool. 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. The averaging kernels are also used to compute the number of degrees of freedom of retrieved temperature and water vapor in order to estimate the number of useful independent observations contained in the infrared and microwave observations. Our work uses data obtained from the Suomi National Polar-orbiting Partnership (S-NPP) Cross-track Infrared Sounder (CrIS) and the Advanced Technology Microwave Sounder (ATMS) to diagnose the vertical resolution of NUCAPS retrieved sounding products over different latitudes and seasons, and to support comparisons of retrievals against correlative radiosonde measurements. This work is expected to be extended to other NUCAPS products, since the generation of the averaging kernels is a functionality embedded as part of NUCAPS.