摘要
为了更好地理解西北干旱区大气混合层(ML)厚度的变化特征及其对当地沙尘气候形成的影响,利用民勤2006—2008年3—6月逐日08时和20时探空资料、降水和日最高气温,计算和分析了最大混合层厚度、逆温层特征和垂直风场及其对沙尘气候形成的影响。结果表明,民勤沙尘天气的大气边界层有显著的昼夜变化,白天厚、逆温强而多;沙尘天气的最大混合层厚度在2 600 m左右,介于无降水与有降水天气之间;扬沙主要由锋面中的冷空气引起,而沙尘暴主要由低层风场的剧烈扰动和500 m以上高层冷锋入侵引起。沙尘暴发生前近地面风场有明显的扰动,沙尘暴发生时在500 hPa以下有显著的冷空气活动,白天较强。能见度小于100 m的强沙尘暴夜间风速大,冷空气较强。
To better understand distribution and variation of atmospheric mixed layer （ML） thickness and the impact of the ML thickness on the sand-dust climate over Northwest China, the maximum ML thickness, inversion layer characteristics, vertical wind field and their impacts on sand-dust climate formation have been calculated and analyzed by utilizing the daily observed sounding data at 08：00 and 20：00, precipitation and maximum temperature data at Minqin from May to June during 2006 2008. The atmospheric boundary has an obvious diurnal variation, and the ML thickness is deeper, inversion layer is stronger and more in daytime than at night. The maximum ML thickness of sand-dust is about 2 600 m, which is between no rainfall and rainfall. The blowing sand events are mainly resulted from cold front, but sandstorm mainly resulted from strong wind disturbance in lower atmosphere and cold front above 500 m in upper atmosphere. There is an obvious wind disturbance near surface before sandstorm, and when sandstorm happen there is obvious cold air below 500 hPa, which is stronger in daytime. When the strong sandstorms with visibility less than 100 m happen there is strong wind and cold air at night.
出处
《中国沙漠》
CSCD
北大核心
2011年第3期757-764,共8页
Journal of Desert Research
基金
国家自然科学基金重点项目(40830957)
"十一五"国家科技支撑计划重点项目第四课题共同资助
关键词
沙尘
最大混合层厚度
逆温层
垂直风场
民勤
sand-dust
maximum mixed layer thickness
inversion layer
vertical wind field
Minqin
