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基于雨雪天气背景的微波辐射计斜路径与天顶观测的反演结果对比分析

Comparative analysis of the zenith and off-zenith retrieved results from microwave radiometer in rain and snow weather conditions

  • 摘要: 为检验斜路径观测反演方法对雨雪天气背景下微波辐射计反演结果的改进,以2014 年2 月17—18 日发生在武汉的一次雨雪过程为例,利用武汉观象台MP-3000A 型微波辐射计天顶方向和斜路径观测反演的温度、相对湿度、水汽密度、液态水含量等廓线产品,分别与武汉观象台L 波段探空资料,以及GPS-MET 和Thies Clima 激光雨滴谱仪的观测资料进行了对比检验。结果表明:(1) 微波辐射计以斜路径方向观测,可以较好地消除K、V 波段亮温信号饱和现象,亮温随降水强度的变化出现起伏波动的特征;(2) 微波辐射计斜路径方向的反演产品与探空观测的相关性较好;(3) 与GPS-MET 观测的大气整层可降水量(PWV)比较,斜路径观测反演的PWV 虽然整体偏大,但走势一致,而天顶方向的反演产品在有降水出现时,跃增明显;(4) 与雨滴谱比较,斜路径方向观测时,地面降水强度的峰值与云中液态水丰沛区有着很好的对应关系。

     

    Abstract: In order to test the improvement of results in the off-zenith directions under rain and snow weather, the retrieved temperature, humidity,vapor density and liquid water density profiles from MP-3000A microwave radiometer (MWR) of the zenith and off-zenith observations from 17 to 18 February 2014 are studied by comparing them with the Thies Clima laser precipitation monitor,L-band sounding data and precipitable water retrieved from GPS-MET from Wuhan station. Results are as follows. (1) If observed at off-zenith, the brightness temperature signal saturation phenomenon at K and V bands can be eliminated effectively. Brightness temperature varies with rainfall intensity. (2)The correlation coefficient between the MWR product retrieved in off-zenith observation and sounding is better. (3) Although precipitable water vapor (PWV) retrieved in off-zenith observation is larger than the GPS/PWV, their trends are consistent. In contrast, there is a clear jump for the result in zenith observation after precipitation occurs. (4) There is a good corresponding relationship between the accumulation of cloud liquid water retrieved in off-zenith observation and the enhancement precipitation intensity.

     

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