A Physical Approach for a Simultaneous Retrieval of Sounding, Surface, Hydrometeor and Cryospheric Parameters from SNPP/JPSS ATMS

We present in this study the results obtained when applying a physical algorithm based on a variational methodology, to SNPP/ATMS data, for a consistent retrieval of geophysical data in all-weather conditions. The algorithm, which runs operationally at the U.S. National Oceanic and Atmospheric Administration (NOAA), is applied routinely to a number of sounders from the POES, DMSP and MetOp satellite constellations and has been extended recently to Suomi-NPP/ATMS. It is also scheduled to be applied to future JPSS satellites. The variational methodology, which relies on a forward operator, in this case called the Community Radiative Transfer Model (CRTM), allows for solving the inversion of the radiometric measurements into geophysical parameters which have a direct impact on the brightness temperatures. The parameters that are produced by this Microwave Integrated Retrieval System (MiRS) algorithm, include the atmospheric temperature T(p), moisture Q(p) and vertically-integrated total precipitable water (TPW), the surface skin temperature (Tskin) and surface emissivity (emiss) as well as the hydrometeor products of non-precipitating cloud liquid water (CLW), rain and ice water paths (RWP, IWP). In this algorithm, a simple post-processing is applied to the 1DVAR-generated emissivity to derive cryospheric products (snow water equivalent SWE and sea ice concentration SIC) when the data are measured over these surfaces. The post-processing is also applied to the hydrometeors products to generate a surface rainfall rate (RR). This comprehensive set of sounding, surface, hydrological and cryospheric products generated from SNPP/ATMS is therefore radiometrically consistent, meaning that when input to the forward operator, it will allow the simulation of the actual brightness temperatures measured within the instrument noise levels. The geophysical consistency between the products, also critical, is satisfied thanks to the physical approach adopted and the geophysical constraints introduced through the correlation matrix used in the variational system. The results shown in this study confirm that the performances of all products are within the expected accuracy and precision, and comparable to performances usually obtained with single-parameter dedicated algorithms, with perhaps the significant added value that they are both radiometrically and geophysically consistent.