Application Experiment of Assimilating Beidou Satellite Navigation Round-Trip Sounding Data Observed in Guangdong Province Using CMA-GD Model
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摘要: 为了解华南区域北斗导航往返探空资料的性能及其对华南区域模式预报的影响,以一个月北斗导航探空资料,分别与L波段观测资料和欧洲中心分析场进行比较分析。结果发现,北斗导航资料与L波段上升段资料之间的速度均方根误差 < 1 m·s-1,温度均方根误差 < 1 °,相对湿度的均方根误差 < 10%。北斗导航探空资料与欧洲分析场标准差在对流层内U、V分量 < 2 m·s-1;温度比分析场偏低~1 °;湿度在大气层中除了在400~ 200 hPa附近偏干5%外,其余偏湿5%~15%。对流层以上的各要素标准差均大于对流层。分别对一次空气影响过程、台风登陆过程进行同化对比试验发现,同化北斗导航探空资料试验与同化L波段资料试验的各级别降水TS互有高低,前者试验24 h台风路径预报有32%的提高,反映出与同化L波段单一的上升资料试验相比,北斗导航的往、返探空资料的同化对短期的降水预报、台风路径预报有着中性至正的改善作用。Abstract: To reveal the quality of Beidou satellite navigation round-trip sounding data for the South China region and its impact on the CMA-GD model, the present study compared a one-month dataset of Beidou satellite navigation sounding observations with L-band sounding data and reanalysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF). The results show that the root mean squared errors (RMSE) between Beidou satellite navigation data and L-band sounding data were less than 1 m · s-1 for wind speed, less than 1℃ for temperature, and less than 10% for relative humidity. The standard deviation of observed wind speed from Beidou sounding data was less than 2 m · s-1 in the troposphere, and the observed temperature was ~1 K lower than corresponding ECMWF reanalysis data. The observed humidity in the atmosphere was 5% dryer near 200 hPa, while, in other layers, it was 5%~ 15% wetter than corresponding ECMWF reanalysis data. The standard deviations of each variable (wind, temperature, and humidity) above the troposphere were greater than those of the troposphere. Case studies of a cold air intrusion event and a typhoon landfall process reveal that the assimilation of Beidou navigation sounding data yielded comparable results to the assimilation of L-band data in terms of precipitation prediction scores (TS). Notably, the 24-hour typhoon track forecast improved by 32% when using Beidou navigation data, demonstrating that the assimilation of round-trip sounding data has a neutral to positive impact on short-term precipitation and typhoon track forecasts compared to the assimilation of L-band ascent-only data.
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图 10 2022年8月25日20时三组试验的降水TS
说明同图 8。
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