多普勒声雷达对化音地区风场结构探测的初步分析

PRELIMINARY ANALYSIS ON THE STRUCTURE OF WIND FIELD SOUNDED BY DOPPLER SODAR AT HUAYIN STATION

本文利用1990年8月多普勒声雷达在“HEIFE”区化音站探测的资料,对该地区的PBL结构进行了初步分析。结果表明,用声雷达回波强度的双对数廓线确定大气边界层高度仍不失为一有效的方法。大气边界层高度演变过程的特点是:白天对流层边界发展较快,但维持时间较短;而夜间稳定边界层维持时间较长,且在其发展较高时,在近地层又发展出一个新的稳定层结,呈现多层次的SBL结构。ML内垂直风速方差的归一化结果与Lenschow大致相同。另外,在一次冷锋过境天气背景下风场出现低空急流结构。

The structure of Planetary Boundary Layer(PBL) has been analysed preliminarily by using the data sounded by Doppler Sodar in August, 1990 at Huayin station, which is in the 'HEIFE' area. The results show that it is an effective method to determine height of the PBL using the data of echo intensity of Doppler Sodar. Evolution feature of the PBL's height is: the Mixed Layer (ML) increases rapidly in daytime, but it can last for a short time, while Stable Boundary Layer(SBL) can last for a long time in nocturnal. When the SBL developing deeply, a new stable layer grows between in the ground layer, hence a structure of multi-layer SBL occurs. The normalized variance of vertical wind-speed in the ML agree well with that of Lenschow's(1980). A completed process about formation, growth and disappearance of the Low-Level Jet(LLJ) was observed under the background that a cold front passed on 20 August.