基于ERA-interim再分析资料的ASCAT风场产品在南海的精度评估及南海月平均风场特征分析

Validation of ASCAT satellite scatterometer winds based on ERA-interim and monthly mean wind field over the South China Sea

利用ERA-interim再分析资料作为参照,统计分析了南海季风盛行时ASCAT散射计L2B和L3风场产品的误差特征。结果表明:季风盛行时,南海中南部大部分海域,ASCAT两种散射计风场产品精度较好,与设计精度一致,风速标准偏差小于2 m/s,偏差小于1 m/s,风向标准偏差小于20°,偏差小于5°,ASCATL2B相对L3产品表现更好,西南风盛行时,风场相关性强,在0.8以上,ASCAT与ERA-interim一致性好,东北风盛行时,风场也具有强相关,不过在南海东部海域,风向相关性较弱,小于0.7。另外,利用ASCAT L2B分析了南海月平均风场分布特征,结果表明:南海季风盛行时,存在两个风速大值中心,分别位于南海中南部和台湾海峡及巴士海峡一带,其位置和大小随时间而变化。

Based on the ERA-Interim surface wind analysis generated at the European Center for Medium Range Weather forecasts, the errors characteristics of two ASCAT wind field products Level2B and Level3 are analyzed when the monsoon is prevailing in the South China Sea. The results show that： ASCAT wind field products perform well which meet the accuracy requirement in the most areas of the South China Sea. The standard deviation of ASCAT wind speed and direction is less than 2m/s and 20°, and the bias is less than 1m/s and 5°, respectively, while the ASCAT L2B is better. When the southwest is prevailing, the ASCAT wind field have a good consistency and large correlation which is higher than 0.8 with the ERA-interim, and when it is northeast, the correlation is also good, while in the east of the South China Sea, the correlation rate is less than 0.7. Besides, the ASCAT L2B are used to the climatic characteristics of the South China Sea. It is shown that there are two average wind speed value centers： one is located at the central south 108°E,10 °N of South China Sea, while the other is near the Taiwan and Bashi Strait whose site and intensity change with time.