摘要
东亚春季冷锋后的强风及其伴随的系统下沉气流和叠加其上的阵风,都对当地起沙十分有利。但此系统的下沉气流却压制着沙尘,使之不能上扬到大气边界层内。经过仔细计算和分析发现,正是阵风的三维相干结构,使得积聚在风沙边界层的沙尘可以持续地克服系统的下沉气流,而不断上扬到大气边界层的中上层。再藉中上层和其上系统的上升气流,将沙尘带到对流层,扩散到更大范围和传送到远方。这是东亚春季强风起沙扬尘最常见和最有效的机理。
The strong wind （boundary level jet） with descending motion and the superimposed gustwind after the passage of spring cold front in northern China are very favorable for the dust emission. However, the systematic descending air motion keeps the dust particles emitted from soil surface within the bottom levels and suppresses their entrainment into the atmospheric boundary layer. By carefully analyses and calculations we revealed that owing to the 3-dimensional coherent structure of the gustwind dust particles can effectively overcome the systematic descend ing air motion and penetrate from the bottom levels into the atmospheric boundary layer in impulsive form one after another, and then propagate into and diffuse in the upper levels of atmospheric boundary layer and troposphere where the ascending air motion is prevailing. This is a very effective mechanism of soil erision and dust entrainment.
出处
《气候与环境研究》
CSCD
北大核心
2007年第3期251-255,共5页
Climatic and Environmental Research
基金
国家财政部"西北地区土壤水分
沙尘暴监测预测研究"项目(Y0101)
关键词
边界层急流
阵风
相干结构
起沙
扬尘
soil erosion, dust entrainment, gustwind, coherent structure, boundary layer jet
