土壤水分对沙尘暴的阈值反应———以内蒙古中西部地区为例

Threshold value response of soil moisture to dust storm:a case study of midwestern Inner Mongolia Autonomous Region

以2001年4月至2003年6月内蒙古中西部地区逐时观测的土壤体积含水百分率资料为基础,论述了土壤体积含水百分率的时间变化规律及其对沙尘暴的阈值反应。得到的主要结论是:(1)土壤体积含水百分率有着单峰型日波动反应,最高和最低值分别出现在午后4时和午前9时。(2)土壤体积含水百分率的月际变化基本遵循以1a为周期作简单振动的变化规律,最低值出现在3～4月。土壤体积含水百分率全年波动介于18.5%～37.3%之间,年平均值为26.5%。(3)沙尘暴的发生在土壤体积含水百分率含量一定范围内并不随土壤含水量的降低而发生明显变化,但当土壤体积含水百分率低于19.5%时,则随着土壤体积含水百分率的降低而明显增加,表现为土壤体积含水百分率有明显的阈值反应。(4)引进沙尘暴时度的概念研究了沙尘暴发生的持续时间,由沙尘暴时度与土壤体积含水百分率的指数关系发现,在时度大于200min和小于120min的两类沙尘暴中,土壤体积含水百分率每降低1%,沙尘暴时度将分别增加19.94min和10.14min。

Based on hourly percentage of soil volume moisture date observed from April 1,2001 to June 30,2003 in midwest of Nei Monggol of China, the change regulation of percentage of soil volume moisture and its threshold response to dust storm are explained in this paper, from which some important results can be drawn as follows: (1)The daily variation of percentage of soil volume moisture shows a single peak. Its highest and lowest values occure at 4pm and 9am, respectively; (2)The monthly variation in percentage of soil volume moisture shows a one year cycle, and its lowest value lies in period of March to April; Its monthly mean value is waved between 18.5% and 37.3%, its annual mean value is 26.5%; (3)Along with decrease of percentage of soil volume moisture, occurrence of dust storm increase only when the percentage lower than 19.5%, which shows as a threshold value in evidence; (4)The duration of dust storm will increase19.94 min and 10.14 min for the durations larger than 200 min and smaller than 120 min respectively,as the percentage of soil volume moisture decrease 1% .