基于野外观测的巴丹吉林沙漠跃移起沙研究

Saltation emission in the Badain Jaran Desert:A field observation-based research

跃移起沙是风沙运动的主要形式之一,与区域土壤风蚀、沙尘气溶胶排放等地表过程关系密切。为了厘清巴丹吉林沙漠跃移起沙的规律,在其北缘拐子湖地区开展了跃移起沙和微气象观测试验。试验结果表明:1)试验点全年跃移起沙时长为186.6h,占总观测时长的2.1%;最大小时起沙时长为3596s,最大小时起沙量为384.5kg·m^(-1)。2)跃移起沙时长和起沙量的高值(大于平均值)均出现在3-5、11-12月,分别占到全年的73.9%和81.8%;起沙时长的季节分布为春季>冬季>夏季>秋季,起沙量的季节分布则为春季>秋季>冬季>夏季。3)跃移起沙主要发生在白天(8:00-19:00),起沙时长和起沙量分别占到全天的81.1%和82.0%;两者的最大值均出现在14:00,最小值均出现在5:00。4)跃移起沙风速分布范围为8.5-10.5m·s^(-1),平均值为9.7m·s^(-1);跃移起沙风速与气温呈现负相关关系,与水汽压和土壤湿度呈现正相关关系。

Saltation activity is one of the main forms of wind sand movement,which is closely related to the surface processes such as regional soil erosion and dust aerosol emissions.In order to clarify the characteristics of saltation emission in the Badain Jaran Desert,saltation activity and micro meteorological observation experiments were conducted in the northern edge of the Guaizi Lake area.The analysis results indicate that:1)The annual total duration for saltation emission at the experimental site is 186.6 hours,accounting for 2.1%of the total observing time,and the duration for maximum hourly saltation emission is only 3596 seconds,and the maximum hourly saltation emission amount is 383.4kg·m^(-1).2)The high values of saltation emission duration and amount(greater than the average value)both occur from March to May and November to December,accounting for 73.9%and 81.8%of the entire year,respectively.The seasonal distributions of saltation emission duration consistent with spring>winter>summer>autumn,while the seasonal distributions of saltation emission amount consistent with spring>autumn>winter>summer.3)The saltation emission mainly occurs during the daytime(8:00-19:00),with the saltation emission duration and amount accounting for 81.1%and 82.0%of the total day,respectively.The maximum values of saltation emission duration and amount both occur at 14:00 and the minimum values occur at 5:00.4)The distribution range of threshold velocity for saltation emission is 8.5-10.5m·s^(-1),with an average value of 9.7m·s^(-1),and there is a negative correlation between the threshold velocity and temperature,and a positive correlation with water vapor pressure and soil moisture.