成都西部山地和平原过渡区边界层水平风场区域差异分析

Analysis of Horizontal Wind Field Regional Difference within Boundary Layer in Chengdu West Mountainous Area and Plain Transition Area Based on Wind Profile Radar

利用2022年1月1日至12月31日成都市西部沿山和东部平原地区的风廓线雷达资料,分析大气边界层水平风场垂直结构及日变化趋势的区域差异。结果表明:①成都市边界层低层盛行风向存在东西区域差异,西部山区盛行北东北风,东部平原盛行东北风,且不存在季节差异;边界层中高层盛行风向不存在东西区域差异,表现为与西侧山脉走向一致的东北风和西南风交替出现。②成都市东西部的边界层平均风速廓线变化趋势一致,相同探测高度东部平原的水平风速大于西部沿山。③边界层低层西部沿山地区受局地山谷风影响,在四季均存在显著的水平风向日变化,白天盛行东南风,夜间盛行西北风。④相同探测高度水平风速的日变化特征没有区域差异,在四季基本一致,为单峰单谷型,最小值在白天,最大值在夜间。⑤成都市东西区域的低层大气边界层风场特征的差异主要由西部沿山地区局地复杂地形造成。

The wind profile radar data observed from the western mountainous and eastern plain areas of Chengdu from 1 Jan to 31 Dec 2022 are used to analyse the regional differences in the vertical structure and daily variation trend of the boundary layer wind field.The results indicate that:(1)There are regional differences in the prevailing wind direction of the lower boundary layer in Chengdu,with north-north-east winds prevailing in the western mountains area and northeast winds prevailing in the eastern plains,and without seasonal difference.While there is no regional difference in the prevailing wind direction between the east and west regions in the middle and upper boundary layer,both occur alternately with northeast and southwest winds that are consistent with the direction of the western mountain range.(2)The variation trend of the average wind speed profile in the boundary layer between the eastern and western areas of Chengdu is consistent,and the horizontal wind speed in the eastern plain area of the same detection height layer is greater than that in the western mountains area.(3)The local mountain-valley breeze is significant in the lower boundary layer of the western mountains area;the valley breeze with southeast winds prevails during the day;and the mountain breeze with northwest winds prevails at night.(4)There are no regional differences in the diurnal variation characteristics of horizontal wind speed at the same detection height layer,and it is a“single peak and single valley”type,with a peak during the day and a valley at night.(5)The differences in the wind field characteristics of the lower boundary layer between the east and west regions of Chengdu are mainly caused by the local complex terrain of the western mountains area.