The NOAA Microwave Integrated Retrieval System (MiRS): Recent Science Improvements and Validation Results

The Microwave Integrated Retrieval System (MiRS) has been the NOAA official operational microwave retrieval algorithm since 2007 and is currently run operationally on microwave data from NOAA-18, NOAA-19, MetopA, MetopB/AMSU-MHS, DMSP F-17, F-18/SSMIS, Suomi-NPP/ATMS, and Megha-Tropics/SAPHIR. It has also been run experimentally on data from TRMM/TMI, Aqua/AMSR-E, GCOM-W1/AMSR2, and GPM/GMI. Future plans include operational processing of JPSS-1/ATMS, DMSP F-19/SSMIS, and GPM/GMI data. The inversion within MiRS follows a 1D-variational methodology, in which the fundamental physical attributes affecting the microwave observations are retrieved physically, including the profile of atmospheric temperature, water vapor, liquid and frozen hydrometeors, as well as surface emissivity and temperature. The community radiative transfer model (CRTM) is used as the forward and Jacobian operator to simulate the radiances at each iteration prior to fitting the measurements to within the noise level. The retrieved surface properties are then used to determine surface physical characteristics, including, when appropriate, cryospheric parameters such as sea ice concentration, ice age, and snow water amount, using pre-determined relationships that link emissivity and effective skin temperature to these parameters. We present a review of science improvements included in the recently released MiRS v11.1 that have led to higher quality atmospheric and surface parameter retrievals, with the improvements quantified by comparison with relevant atmospheric and surface reference data.