HY-2B卫星散射计海面风场产品质量分析

Accuracy analysis of the retrieved wind from HY-2B scatterometer

星载微波散射计是获取全球海面风场信息的主要手段,HY-2B卫星散射计的成功发射为全球海面风场数据获取的持续性提供了重要保障。本文利用欧洲中期天气预报中心(EuropeanCenter forMedium-RangeWeatherForecasts,ECMWF)再分析风场数据、热带大气海洋观测计划(TropicalAtmosphereOceanArray,TAO)和美国国家数据浮标中心(National Data Buoy Center,NDBC)浮标获取的海面风矢量实测数据,对HY-2B散射计海面风场数据产品的质量进行统计分析。分析表明,HY-2B风场与ECMWF再分析风场对比,在4~24m·s^-1风速区间内,风速和风向均方根误差(root mean squareerror,RMSE)分别为1.58m·s^-1和15.34°;与位于开阔海域的TAO浮标数据对比,风速、风向RMSE分别为1.03m·s^-1和14.98°,可见HY-2B风场能较好地满足业务化应用的精度要求(风速优于2m·s^-1,风向优于20°)。与主要位于近海海域的NDBC浮标对比,HY-2B风场的风速、风向RMSE分别为1.60m·s^-1和19.14°,说明HY-2B散射计同时具备了对近海海域风场的良好观测能力。本文还发现HY-2B风场质量会随风速、地面交轨位置等变化,为用户更好地使用HY-2B风场产品提供参考。

Spaceborne microwave scatterometer is the most efficient instrument to measure the global ocean surface wind.The successfully launched HY-2B scatterometer is an important guarantee to continue the measurement of global ocean surface wind.In this paper,we use the European Center for Medium-Range Weather Forecasts(ECMWF)reanalysis wind data,Tropical Atmosphere Ocean Array(TAO)and National Data Buoy Center(NDBC)buoy wind data to estimate the accuracy of the HY-2B retrieved wind.Our statistical results show that at speed range from 4 to 24 m·s^-1,the retrieved wind speed root mean square error(RMSE)with respect to the ECMWF wind speed is 1.58 m·s^-1,and the direction RMSE is 15.34°,while the speed and direction RMSEs with respect to the TAO buoys located in the open ocean are 1.06 m·s^-1 and 15.98°,respectively.Thus,the retrieved wind well satisfies the operational precision requirement of the HY-2B scatterometer,that is,the speed and direction RMSEs should be better than 2 m·s^-1 and 20.00°,respectively,for the open ocean.Moreover,the NDBC buoys are mainly located in immediate offshore areas,HY-2B wind speed and direction RMSEs are 1.60 m·s^-1 and 19.14°,respectively,which shows that HY-2B scatterometer has good ability to measure wind of offshore sea areas.We also reveal that the retrieved wind error varies with wind speed and cross track position of wind vector cell,which will provide the users with reference for the effective application of HY-2B wind product.