Assimilation of data from the MWHS-II onboard the first early morning satellite FY-3E into the CMA global 4D-Var system

Meteorological applications

article

Hongyi Xiao¹  Wei Han¹  Peng Zhang³  Yihong Bai³ 

[1] CMA Earth System Modeling and Prediction Centre;State Key Laboratory of Severe Weather;Innovation Center for FengYun Meteorological Satellite;Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites, National Satellite Meteorological Center ,(National Center for Space Weather), China Meteorological Administration

关键词: 4D-Var;    CMA_GFS;    FY-3E;    MWHS-II;    satellite data assimilation;   

DOI  :  10.1002/met.2133

学科分类：社会科学、人文和艺术（综合）

来源: Wiley

【 摘 要 】

Radiance data from satellite microwave radiometers are becoming increasingly important in the assimilation of numerical prediction systems. FengYun-3E (FY-3E), which was launched in July 2021, as the first early morning orbital satellite among FY-3 polar-orbiting meteorological satellite series, can greatly enhance the atmospheric sounding capacity in three orbits compared with the two-orbit system that is distributed in morning or afternoon orbit. Focusing on MicroWave Humidity Sounder-2 (MWHS-II) onboard it, the schemes for thinning, quality control, bias correction and observational error calculation are developed. The scan-position-dependent biases are assessed in each channel and increasing biases near the edges of scanline are found in several temperature-sounding channels. The data quality is compared with four analogous instruments used in Global/Regional Assimilation and Prediction System–Global Forecast System (CMA_GFS), and the performance improvements are confirmed relative to the previous FY-3C/D MWHS-II. Three batch experiments were implemented in CMA_GFS with four-dimensional variational (4D-Var) system—assimilating only the humidity-sounding channels, the temperature-sounding channels and the combined channels—to reveal the impact of assimilation by different channel groupings. Analysis results conclude that FY-3E MWHS-II radiances are beneficial to the humidity and temperature analysis fields. These results emphasize the advantage of simultaneously assimilating the humidity/temperature-sounding channels, in which the former dominates the improvement above 700 hPa while the latter have a positive impact below 700 hPa. The forecast results also show that assimilating both the 183- and 118-GHz channels further improves the forecast skills, especially short- to medium-term forecasts in both hemispheres. FY-3E MWHS-II also improves the short-term prediction of heavy rain, which is always weakly predicted in global forecast systems. This study shows that a three polar orbits system that FY-3E began can produce marked effects in the numerical prediction system. This study also shines light on the application potential of the distinctive 118-GHz channels of MWHS-II.

【 授权许可】

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