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Abstract
AMSU-A (Advanced Microwave Sounding Unit-A) measurements for channels that are sensitive to the
surface over land have not been widely assimilated into numerical weather prediction (NWP) models due to
complicated land surface features. In this paper, the impact of AMSU-A assimilation over land in Southwest
Asia is investigated with the Weather Research and Forecasting (WRF) model. Four radiance assimilation
experiments with different land-surface schemes are designed, then compared and verified against radiosonde
observations and global analyses. Besides the surface emissivity calculated from the emissivity model and
surface temperature from the background field in current WRF variational data assimilation (WRF-VAR)
system, the surface parameters from the operational Microwave Surface and Precipitation Products System
(MSPPS) are introduced to understand the influence of surface parameters on AMSU-A assimilation over
land.
The sensitivity of simulated brightness temperatures to different surface configurations shows that us-
ing MSPPS surface alternatives significantly improves the simulation with reduced root mean square error
(RMSE) and allows more observations to be assimilated. Verifications of 24-h temperature forecasts from
experiments against radiosonde observations and National Centers for Environmental Prediction (NCEP)
global analyses show that the experiments using MSPPS surface alternatives generate positive impact on
forecast temperatures at lower atmospheric layers, especially at 850 hPa. The spatial distribution of RMSE
for forecast temperature validation indicates that the experiments using MSPPS surface temperature ob-
viously improve forecast temperatures in the mountain areas. The preliminary study indicates that using
proper surface temperature is important when assimilating lower sounding channels of AMSU-A over land.
Key words: AMSU-A, surface temperature, microwave surface emissivity, radiance assimilation
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Citation
HE Wenying, LIU Zhiquan, CHEN Hongbin. 2011: Influence of Surface Temperature and Emissivity on AMSU-A Assimilation over Land. Journal of Meteorological Research, 25(5): 545-557.
HE Wenying, LIU Zhiquan, CHEN Hongbin. 2011: Influence of Surface Temperature and Emissivity on AMSU-A Assimilation over Land. Journal of Meteorological Research, 25(5): 545-557.
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HE Wenying, LIU Zhiquan, CHEN Hongbin. 2011: Influence of Surface Temperature and Emissivity on AMSU-A Assimilation over Land. Journal of Meteorological Research, 25(5): 545-557.
HE Wenying, LIU Zhiquan, CHEN Hongbin. 2011: Influence of Surface Temperature and Emissivity on AMSU-A Assimilation over Land. Journal of Meteorological Research, 25(5): 545-557.
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