海洋二号卫星3个主要载荷风速测量比较

Comparison of wind speed from 3 main payloads of HY-2 satellite

海面风速对海洋中动能的转移、海气间物质和能量的交换具有非常重要的作用。海洋二号(HY-2)卫星搭载的雷达高度计、微波散射计和扫描微波辐射计均可以用来探测海面风速。区别是雷达高度计只能测量星下点风速,微波散射计可以得到宽刈幅的风场(包括风向和风速),扫描微波辐射计可获得宽刈幅的风速。为了更好地分析3个载荷风速测量能力,针对2013年9月19日"天兔"台风影响海域范围内的海面风速,比较了3种载荷的探测结果。结果表明,在小于20 m/s风速范围内,雷达高度计和微波散射计探测到的风速非常接近,标准偏差小于2m/s,而扫描微波辐射计测量的风速比另外两个载荷测量的风速大;在20～35m/s风速范围内,雷达高度计和扫描微波辐射计风速较为接近;在大于35 m/s的高风速区,只有扫描微波辐射计可以探测出风速,但其测量精度还需要进一步验证。

Sea surface wind speed plays a very important role in the transfer of kinetic energy in the ocean and the exchange of the matter and energy in the air-sea surface. There are three payloads on HY-2 satellite which can be used to detect the sea surface wind speed. The payloads are radar altimeter,microwave scatterometer and scanning microwave radiometer. The difference is that the radar altimeter can measure the wind speed at the nadir point of the HY-2 satellite,the microwave scatterometer can detect the wide swath wind field,and the scanning microwave radiometer can measure the wide swath wind speed only. In order to analyze the capacity of the three payloads,in this study,the Typhoon Usagi was selected for comparing the ability of the three payloads to measure the wind speed. It turned out that when the wind speed is lower than 20 m/s,the wind speed from radar altimeter is much the same as that from microwave scatterometer. The standard deviation is less than 2 m/s. But when wind speed is between 20 m/s and 35 m/s,the wind speed of radar altimeter is close to the scanning microwave radiometer. Only the scanning microwave radiometer is able to detect the wind speed higher than 35 m/s. Before using it to measure the wind speed higher than 35 m/s,we have to assess the accuracy of measurement.