从单Doppler速度场反演风矢量场的VAP方法

THE VAP METHOD TO RETRIEVE THE WIND VECTOR FIELD BASED ON SINGLE-DOPPLER VELOCITY FIELD

  • 摘要: 从单Doppler速度场反演风矢量场的VAP(Velocity Azimuth Processing)方法是在假定相邻方位角的风矢量相等的前提下,从单部Doppler雷达所测得的各个距离圈上的径向速度随方位角分布的廓线推算风向和风速的方法。这个假定可以保证反演所得的风矢量场中仍保留次天气尺度的风场信息。对VAP方法反演公式的误差分析表明,反演出的风向误差为20-30度,与常规测风的误差相近。风速误差一般为100m/s,但在某些特定的情况下可达到与风速相同的量级(100m/s)。用VAP方法反演风矢量场前必须首先消除原始Doppler速度资料中的脉动。它可以通过简单的一维线性平滑实现。文中给出了一个反演实例,从中可以分析出次天气尺度的切变线和辐合线。常规天气图和UHF雷达的风廓线观测表明,这些次天气尺度系统是存在的。它们与反射率因子分布的配置还表明这些次天气尺度系统是和降水相联系的。

     

    Abstract: Under the assumption that the wind vectors of two contiguous azimuth are same, the VAP (Velocity Azimuth Processing) method is proposed to retrieve the wind vector field from the distributions of Doppler velocity on the distance.circle. The information of sub-synoptic scale can be maintained in the retrieved wind field. The error analysis indicates that the error of retrieved wind direction is about 20 to 30 degree, and the scale of the wind speed error is 100 m/s (it could reach to 101 m/s in special situation).The pulsation in the original data of Doppler velocity has to be removed before the retrieval. It can be brought into being by one-demension linear smooth. The shear line and convergent line with sub-synoptic scale are revealed in a case of retrieved wind field and confirmed by the synoptic charts and the wind profile observed by UHF radar. The disposition of radar echo in the retrieved wind field suggests that the rainfall is associated with those mesoscale synoptic systems.

     

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