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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union
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Volume 9, issue 7
Atmos. Meas. Tech., 9, 3095–3113, 2016
https://doi.org/10.5194/amt-9-3095-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Atmos. Meas. Tech., 9, 3095–3113, 2016
https://doi.org/10.5194/amt-9-3095-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 19 Jul 2016

Research article | 19 Jul 2016

Direct assimilation of Chinese FY-3C Microwave Temperature Sounder-2 radiances in the global GRAPES system

Juan Li1,2 and Guiqing Liu1,2 Juan Li and Guiqing Liu
  • 1National Meteorological Center, China Meteorological Administration, Beijing, 100081, China
  • 2Numerical Weather Prediction Center, China Meteorological Administration, Beijing, 100081, China

Abstract. FengYun-3C (FY-3C) is an operational polar-orbiting satellite carrying the new-generation microwave sounding instruments in China. This paper describes the assimilation of the FY-3C Microwave Temperature Sounder-2 (MWTS-2) radiances in the Global and Regional Assimilation and PrEdiction System (GRAPES) of China Meteorological Administration. A quality control (QC) procedure for the assimilation of MWTS-2 radiance is proposed. Extensive monitoring before assimilation shows that MWTS-2 observations exhibit a clear striping pattern. A technique combining principal component analysis (PCA) and ensemble empirical mode decomposition (EEMD) is applied to the observations to remove the striping noise. Cloudy field-of-views (FOVs) are identified by applying the Visible and InfrarRed Radiometer (VIRR) cloud fraction threshold of 76 %. Other QC steps are conducted in the follow order: (i) coastal FOVs are removed, (ii) eight outmost FOVs are not used, (iii) channel 5 data over sea ice and land are not used, (iv) channel 6 observations are not used if the terrain altitudes are higher than 500 m, and (v) outliers with large differences between observations and model simulations are removed. Approximately 83, 75, 40, and 40 % of the observations are removed by the proposed QC for channels 5–8, respectively. After QC, the global biases and standard deviations are reduced significantly. The assimilation of the MWTS-2 radiances shows a positive impact when the control experiment assimilates only conventional observations. The experiments also show that the analysis and forecast errors are slightly reduced when the striping noise is removed from the observations. The quality control scheme of extracting the striping noise may contribute to the analysis and forecast accuracy. The impact of MWTS-2 is neutral when the conventional data and other satellite data are all assimilated.

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FengYun-3C is an operational polar-orbiting satellite carrying the new-generation microwave sounding instruments in China. It can contribute to the Global Environmental Observing System of Systems. It is anticipated that the data can be useful for the weather forecast. After quality control, the data are put into the Chinese numerical weather prediction (NWP) system. It shows that the microwave temperature observations can have a neutral to positive impact on the NWP system.
FengYun-3C is an operational polar-orbiting satellite carrying the new-generation microwave...
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