基于星载激光雷达数据的海面风速探测

Sea Surface Wind Speed Detection by Using the Data of CALIPSO Lidar

使用新版(Version 3.01)星载激光雷达CALIPSO Level 1剖面数据和Level 2的大气气溶胶光学厚度(AOD)数据反演全球海面风速。将AOD数据用于大气双程透射率的校正。对CALIPSO所采集的2007年1月、4月、7月和10月532nm波长无云激光测量数据进行应用计算,采用532nm退偏比经验修正海面白帽及水下次表层水体散射的影响,同时选用准同步的AMSR-E海面风速测量值为真值进行对比。对应2007年的4个月,由CALIPSO星载激光雷达532nm单脉冲测量数据反演海面风速的标准偏差分别为1.24、1.24、1.24、1.20m/s,由5km滚动平均数据反演海面风速的标准偏差分别为0.98、1.02、0.98、0.94m/s。结果表明,采用的数据反演方法可行且数据利用率得到提高。

The global sea surface wind speeds are retrieved from the Version 3.01 CALIPSO lidar level 1 profile products and level 2 aerosol optical depth （AOD） products. The corresponding AOD data are used for correction of the two-way atmospheric transmittance, which allows wind speeds retrieval in the presence of significant amount of aerosols. Four months （January, April, July and October, 2007） of the CALIPSO lidar 532 nm data are selected. The AMSR-E sea surface wind speed data are collocated with the CALIPSO data and used for comparison. Effects from whitecaps and subsurface backscattering signals are corrected empirically using the lidar depolarization ratio measurement. The standard deviations of wind speeds retrieved by the CALIPSO lidar single-shot data and those by AMSR-E are 1.24, 1.24~, 1.24, 1.20 m/s, respectively, for January, April, July and October, 2007. The standard deviations are reduced to 0.98, 1.02, 0.98, 0.94 m/s, respectively, when the lidar data is smoothed with a 5 km running window. The results show that the method works well and the data utilizing rate increases.