CYGNSS海面风速固有误差与时空分布特征

Inherent Error and Temporal-Spatial Characteristics of GYGNSS Sea Surface Wind Speed

全球导航卫星系统反射测量(GNSS-R)是一种新兴的海面风速遥感技术,对GNSS-R反演风速进行详细定量分析是该技术从科学研究走向业务应用的必要条件。以气旋全球导航卫星系统(CYGNSS)的风速数据为例,利用时空匹配的浮标风速和欧洲中期天气预报中心(ECMWF)的预报风速数据,详细分析了CYGNSS遥感风速的气候态特征和时空分布特征。基于三配对数据分析方法,阐明了CYGNSS遥感风速的固有误差,并提出了相应的风速标定系数。研究表明:GYGNSS的中低风速(w<10 m·s^(–1))精度较好,但高风速的误差显著增大;风速误差具有良好的时间一致性,但呈现明显的空间分布不均匀现象;总体而言,CYGNSS风速的固有误差约为1.79 m·s^(–1)。研究结果一方面可为CYGNSS风速数据的业务应用提供参考,另一方面也为进一步标定CYGNSS的反射测量信号提供依据。

Global Navigation Satellite System Reflectometry(GNSS-R)is a new technique for the remote sensing of sea surface wind speed.In terms of operational applications,it is necessary to perform a detailed and quantitative analysis on the GNSS-R wind speed.In this paper,wind data of the Cyclone Global Navigation Satellite System(CYGNSS)mission are used to evaluate the capability of GNSS-R in wind remote sensing.First,the collocated buoy winds,as well as the European Centre for Medium-Range Weather Forecasts(ECMWF)winds,are used to analyze the climatologic and the temporal-spa-tial characteristics of CYGNSS wind speeds.Second,a triple collocation analysis is used to estimate the inherent errors and the calibration coefficients of GYGNSS wind.It shows that the quality of CYGNSS wind is promising for wind speed below 10 m·s^(–1),but degrades remarkably at high wind conditions.Moreover,the wind speed error is consistent in the temporal domain,but shows certain dependency on the geographic location.Overall,the inherent error of CYGNSS wind speed is about 1.79 m·s^(–1).The results are not only relevant for the operational application of CYGNSS wind product,but also important for the further inter-calibration of CYGNSS signal.