GPM双频降水测量雷达对降雪的探测能力分析

Study of GPM Dual-Frequency Radar in Detecting Snow

以双频降水测量雷达为主载荷的GPM卫星于2014年2月发射升空。由于轨道倾角以及仪器通道的设置,大大提升了对弱降水和降雪的探测能力。通过四次降雪个例,分析比较了双频降水测量雷达的三种扫描模式(Ku,KaMS和KaHs)对降雪探测能力的差异。结果表明:DPR相态产品和地面实际观测结果比较一致,固态降雪温度<-0.5℃并且降雪发生时的风暴顶高度大多<6 km。Ku波段雷达由于仪器灵敏度的大幅提高.对降雪的综合探测能力最强,而KaMs和KaHS也具有特定的作用。此外,为了保证衰减订正的精度,和非降雪部分的衰减相比,需要主要提高降雪衰减尤其是混合相态湿雪的衰减订正精度。

The Global Precipitation Measurement （GPM） mission core observatory was launched in Febru ary 2014, carrying the dual-frequency precipitation radar （DPR）. The DPR consists of two radars with microwave frequencies of Ka and Ku bands. DPR is expected to extend its ability to capture weak rain and snow in higher latitudes. In order to evaluate the ability of DPR in snow detection, four cases are ana- lyzed. As a result, particle phase products of DPR are consistence with the actual weather condition and the temperature of solid snow is lower than -0.5℃. What＇s more, the heights of most storm tops are lower than 6 km. By comparison, actual Ku-band radar detectability turns out to outperform the Ka band radar in identifying the existence of snow because of an obvious improvement of sensitivity. KaMS and KartS are also useful. In order to improve snow retrieval, the attenuation correction of snow is very important, especially for wet snow.