[p2] Observational issues


Development of cloud detection algorithm for clear-sky assimilation of SSMIS humidity sounding channels and its application to JMA global data assimilation system

Y.Murakami and M.Kazumori (Japan Meteorological Agency)


Satellite microwave radiance observations at 183 GHz contain atmospheric humidity, cloud and precipitation information. They are one of the most important observations to improve and maintain the accuracy of operational numerical weather prediction. Japan Meteorological Agency (JMA) has been utilizing the clear-sky radiance of microwave humidity sounder (MHS) onboard US operational polar orbiting satellites and European polar orbiting meteorological satellites in its global data assimilation system.
Because these channels are affected by cloud liquid water emission and freezing particle scattering in cloudy situations, it is crucial to detect and discriminate the cloud and precipitation affected data for the clear-sky assimilation. Furthermore, their accurate estimation and understanding on individual effects of the liquid and freezing hydrometeor particles in the microwave radiance are inevitable for future all-sky microwave radiance assimilation.
In this initial study, based on the above mentioned elements, a physically-based approach is taken to develop a quality control algorithm for the clear-sky assimilation of Special Sensor Microwave Imager/Sounder (SSMIS) humidity sounding channels. Since SSMIS has 24 channels covering wide range of microwave frequency, it is capable to detect liquid and frozen particle independently. Current cloud and precipitation detecting algorithm of MHS has been refined for the SSMIS humidity sounding channels assimilation. The details of the quality control algorithm and results of the initial data assimilation experiment of the clear-sky data will be presented in the workshop.