两种ASCAT散射计风产品的比较及评估

Comparison and evaluation between two versions of ASCAT scatterometer wind products

基于浮标和步进频率微波辐射计(SFMR,Stepped-Frequency Microwave Radiometer)数据对NASA JPL(Jet Propulsion Laboratory)和RSS(Remote Sensing Systems)公司分别发布的已广泛应用于全球海面风场观测的ASCAT(Advanced SCATterometer)散射计风产品进行了比较和分析。结果表明,两者风速在中低风速(<15 m/s)时基本一致;高风速(>15 m/s)时RSS风速整体高于JPL风速。通过浮标数据对比,风速<15 m/s时两者风速精度一致;风速>15 m/s时两者风速RMS相当,但JPL和RSS风速分别低估和高估。利用SFMR数据检验表明RSS风速与SFMR风速一致性更好。两者风向精度在低风速(<5 m/s)时较低,但随风速增加而提高并趋于稳定。该研究结果对相关科研人员的ASCAT散射计风产品选择具有重要的指导意义。

Advanced SCATterometer（ASCAT） wind product data has been widely used in the observation of global sea surface wind fields. In this study, two ASCAT wind products one released by the NASA Jet Propulsion Laboratory（JPL） and the other by Remote Sensing Systems（RSS） company are compared and analyzed on the basis of buoy data and Stepped-Frequency Microwave Radiometer（SFMR） data. A comparison between these two products shows good agreement at low to moderate wind speeds; however, there is an increase in the wind speed of RSS at speeds of higher than 15 m/s with increasing wind speeds, compared to the performance of JPL. A comparison of buoy data shows an almost identical accuracy for the two wind speed products when the wind speed is lower than 15 m/s. In addition, their RMS is consistent at higher wind speeds（〉15 m/s）, although JPL and RSS wind speeds are underestimated and overestimated, respectively. A comparison using SFMR data shows a better agreement for wind speed with RSS than JPL. The accuracy of the two wind direction products is low at wind speeds under 5 m/s; however, it improves and tends to be stable with increasing wind speed. These results provide important guidance for the selection of suitable ASCAT scatterometer wind products in associated research.