沙漠地区春季近地层气象要素分布规律的观测研究

 利用2005年1月至2006年4月朱日和地区20 m气象塔的风向、风速、气温、相对湿度的观测资料,分析沙漠地区春季近地层气象要素的分布规律。结果表明: 春季温度回升,风速最大,相对湿度最小,利于起沙,故沙尘天气频繁。风速满足幂指数率分布规律,并且幂指数m能够很好的反映出风速梯度的变化情况;在沙尘暴、扬沙、背景、浮尘的天气条件下,春季近地面层风速梯度依次增大,湍流动量、热量交换系数依次减小;风向以西南为主。浮尘、扬沙天气各气层平均增温率分别大于或小于同时段的背景大气;沙尘暴期间温度下降,平均降温率为0.61 ℃\5h-1。春季相对湿度的平均递减率(递增率)与平均增温率(降温率)的大小正相关。浮尘天气相对湿度的平均递减率大于同时段的背景大气;扬沙天气相对湿度的平均递减率小于同时段的背景大气;沙尘暴天气相对湿度增大,平均增大率为2.80%\5h-1。

Study on Meteorological Elements Structure of Atmospheric Surface Layer over Desert Area in Spring

The characteristics of meteorological elements of atmospheric surface layer in spring were studied based on the observational data of wind speed, wind direction, temperature and relative humidity obtained from 20m meteorological tower in Zhurihe of Inner Mongolia from January, 2005 to April, 2006.The results show that the temperature rises rapidly, the wind speed is maximal and the relative humidity is minimal in spring, which is beneficial to drive sand, so the sand dust weather is frequent. The wind speed profile accords with exponential function and the exponential coefficient m could reflect well the change of wind speed at different altitudes. In sand storm, blowing sand, clean air and floating dust weather conditions, the wind speed in atmospheric surface layer raises gradually in spring. Meanwhile, the turbulent exchange coefficient diminishes gradually in spring. The main wind direction is southwest. Compared with clean air, the average rate of temperature increase is larger in floating dust, less in blowing sand. And the change of temperature reduces in dust storm, which is 0.61℃·h-1. There is a positive correlation between the average rates of relative humidity decrease and temperature increase, and also between those of relative humidity increase and temperature decrease in all layers. Compared with clean air, the average rate of decrease is larger in floating dust, less in blowing sand. And the change of relative humidity enhances in dust storm, which is 2.80%·h-1.