Soundings
12. Xuebao Wu
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The ICI Scheme for Retrieving Atmospheric Parameters over China
Xuebao Wu (1), Fengying Zhang (1) and Lydie Lavanant (2)
(1)National Satellite Meteorological Center, Beijing 100081,China
(2)Centre de Météorologie Spatiale, Météo-France, BP 147 22302 Lannion, France
The ICI retrieval scheme with some adaptations is implemented to retrieve the temperature and humidity profiles from NOAA-16 ATOVS measurements over China. The AAPP3 has been installed to process the relay HRPT data from the 3 receiving stations (Beijing, Guangzhou and Urumqi). The radiances from ATOVS instruments are interpolated to the HIRS sounder's field of view. In our processing, the analyses of the Chinese regional NWP model are utilized to create a rolling library of vertical profiles over the last ten days. Once an initial guess profile has been obtained, inversion consists of perturbing this profile under certain limits in order to minimize the error between the measurement and the synthetic brightness temperature of the final profile. The most probable solution is the function minimizing the cost function. In this application, ICI has been run at a thinned resolution of 2 by 2 HIRS pixels which is about 50km*50km. The retrievals are separated due to surface types (sea and land) and cloud conditions (clear and cloudy). The cloud classification is based on AVHRR cloud cover and AMSU precipitation flag. Retrieval results validated against both NWP analyses and radiosondes indicate good agreement between the retrieved temperature and humidity profiles and conventional observations. Figure 1&2 show the statistics between ICI retrievals and observations (NWP analyses plus RAOB measurements) for a ten-day period for NOAA-16 ATOVS retrievals over China.
