The Use of AMSU-A Cloudy Radiances in NCEP Globa Model and HWRF

The current operational 3DVAR/Ensemble Grid-point Statistical Interpolation (GSI) analysis system used in conjunction with the National Centers for Environmental Prediction (NCEP) global spectral model at the Environmental Modeling Center (EMC) and with the Hurricane Weather Research and Forecast System (HWRF) assimilates satellite radiances under clear-sky conditions only. The satellite radiances are under-utilized in cloudy and precipitating areas where numerical weather prediction is challenging. The inclusion of cloudy radiances in the analysis may be potentially beneficial to forecasts by providing greater coverage in meteorologically active areas and constraining cloud and precipitation directly. The basic capabilities for assimilating cloudy radiances in the GSI have been developed and diagnostics of these capabilities to assimilate Advanced Microwave Sounding Unit A (AMSU-A) radiances under all-sky conditions are currently underway, which will provide guidance for further developments.

This paper will present the use of AMSU-A radiances under all-sky conditions in the NCEP global model including summaries and results for the following aspects: (1) validation of the observation operator for non-precipitating clouds; (2) characteristics of innovations; (3) estimation of observation error; (4) quality control; (5) single observation experiments for diagnosing the effectiveness of ensemble estimated background error covariances. In addition, the validation of the observation operator for precipitating clouds and the characteristics of innovations from the HWRF model will also be discussed.