风廓线雷达探测零度层亮带的试验研究

Study on Bright Band Detection Using Wind Profiler Radar

L波段风廓线雷达采用相干累积技术提高雷达探测灵敏度,用于对降水云体垂直探测,能获取高分辨率的云体返回信号的全谱信息。应用它对2009年5月14日层状云降水过程中出现的零度层亮带进行了连续探测研究,得到零度层亮带附近区域中返回信号的谱参数(功率、平均多普勒速度、速度谱宽)和回波功率谱密度分布随高度的变化和演变特征。在零度层亮带区附近质点的冰水转化过程中,云体中大部分冰晶、雪花从-1.3℃附近开始表面融化,0.8℃附近冰晶、雪花的整体冰框架开始破碎分离成尺度较小的液态降水质点,3.5℃附近冰晶、雪花全部融化为液态降水质点。同时,在0.8℃附近约300m厚度的层次中观测到回波强度谱区范围突然展宽现象,这反映出降水质点的冰水转化引起局部环境强烈降温可能导致出现少量的细部对流现象。

L-band wind profile is used in coherent accumulation technology to rise radar sounding sensitivity, vertical measurement precipitation cloud body is applied,which can obtain the entire spectrum information of cloud body return signal of high resolution.The wind profiler is used to continuously detect the bright band appeared in stratiform cloud precipitation process on May 14,2009.The variation and evolution characteristics of return signal spectrum parameter（power,average Doppler velocity,speed spectral width） and the changes of power spectral density distribution with the height nearby the region of bright band were obtained. The ice and water transformation process is found near the bright band area,in the cloud the surface of snowflake,ice crystals start to melting near-1.3 ℃,the whole skeleton of snowflake,ice crystal begin breaking into the smaller scale liquid precipitation particles near 0.8 ℃, the ice crystal,snowflake melt to liquid precipitation particles completely 3.5 ℃.At the same time,the levels about 300 m thickness and around 0.8 ℃ can be observed the phenomenon that the echo intensity spectral range stretch suddenly,it reflected that the obvoius decreasing of local environment temperature caused by ice and water transformation of precipitation particle may lead to the few detail convection.