The Expected Impacts of NPOESS Microwave Radiances on Operational Numerical Weather Prediction and Data Assimilation Systems

The NPOESS microwave (MW) sensor suite consists of the Advanced Technology Microwave Sounder (ATMS) and the Microwave Imager/ Sounder (MIS). ATMS is scheduled to fly on the NPOESS Preparatory Project (NPP), as well as NPOESS operational flight units C1 and C3, while MIS is scheduled for flight units C2, C3 and C4. ATMS is a newer lighter and lower power version of the current operational Advanced Microwave Sounding Unit (AMSU) and the Microwave Humidity Sounder (MHS) combined into a single sensor package, with an additional channel in the oxygen absorption region at 51.76 GHz and 3 additional channels in the water vapor absorption band at 165.5 and 183 GHz. The MIS is a conical scanning polarimetric imager and sounder patterned after the heritage WindSat, and DMSP Special Sensor Microwave Imagers and Sounders (SSMI and SSMIS). Numerical Weather Prediction (NWP) and associated Data Assimilation Systems (DAS) routinely assimilate MW sounding radiance data directly using the model background state in conjunction with a fast radiative transfer model (RTM). Critical to the successful operational assimilation of the MW radiance data, as measured by forecast accuracy improvements, are low noise measurements, channel sets that span the vertical space defined within the NWP model, a fast and accurate RTM, and bias correction schemes designed to remove systematic biases in the departures between the observed versus calculated radiances. Given the pre-flight MW sensor channel specifications, noise figures, and knowledge of the antenna patterns, proxy NPOESS MW sensor observations can be constructed and tested in existing assimilation systems. Results of this development, and the benefit of additional preprocessing of the data, as well as the expected impacts of the NPOESS MW sensor data will be presented.