二连浩特地区土壤湿度变化特征及其与沙尘暴关系的初步研究

Variation of Soil Moisture Content and its Relationship with Dust Storms in the Erleahot Region

利用内蒙古自治区中部二连浩特地区2001年4月-2004年4月土壤湿度的逐时观测资料,初步分析了二连浩特地区土壤湿度的变化特征;结合相应的地面气象资料,探讨了土壤湿度与沙尘天气之间的关系。结果表明,二连浩特地区土壤湿度具有1年为周期的变化,每年土壤湿度的峰值出现在降水较多的湿季,土壤湿度与沙尘暴发生次数呈负相关,土壤湿度对该地区沙尘暴的发生有重要影响。

The Erleahot region （43°19′, 111 °58′E） is located in the central area of Inner Mongolia Autonomous Region, China, its total area is 167 km^2, the terrain is level and open, it belongs to the mid-temperate continental monsoon climate, it is windy and cold in winter but hot and dry in summer. The annual temperature is 3.4℃, the annual precipitation is 142.4 mm, and the proportions of precipitation in summer, autumn, spring and winter occupy 67.84%, 17.84%,11.59% and 2.73% of the annual precipitation respectively. The prevailing wind directions are W and NW, the average annual wind speed is over 4.1 m/s, and the annual days of occurring strong winds （≥17.2m/s） varies in a range of 70～80 days, which occur mainly in winter and spring. Moreover, the vegetation coverage is low in the region, thus, dust storms occur frequently, and the 40-year average annual days of occurring dust storms are 8 days during the period from 1962 to 2001. In this paper, the distribution and change characteristics of soil moisture content are preliminarily analyzed based on the hourly soil moisture content data collected in the Erleahot region of Inner Mongolia during the period from April 16, 2001 to April 12, 2004, and the relationship between soil moisture content and dust storms are studied by referring the meteorological date. The results show that the variation of soil moisture content has a one-year periodicity, the maximum soil moisture content occurs in wet season from May to July, and the daily change curve of soil moisture content is unimodel; there is positive correlation between soil moisture content and precipitation, and there is negative correlation between soil moisture content and occurring frequency of dust storms, that is the occurring frequency of dust storms is increased with the decrease of soil moisture content.