塔克拉玛干沙漠近48年起尘速率变化趋势分析

Change trend of dust emission rates in Taklimakan Desert in last 48 years

采用美国环境保护局推荐的公式,分析了塔克拉玛干沙漠1960~2008年PM50和PM30起尘速率的变化趋势及影响因子.结果表明,1960~2008年,塔克拉玛干沙漠PM50和PM30起尘速率及沙尘暴频率均呈显著减小趋势,粉尘粒径越细,起尘速率减幅越大;塔克拉玛干沙漠21世纪初的风沙活动比上世纪60年代减小了65.01%~85.14%;年均风速的减少和年降水量的增加对PM50起尘速率减少的贡献率分别为37.8%和62.2%,年均风速和起沙风频率的减少及年降水量的增加对PM30起尘速率减少的贡献率分别为9.1%、33.2%和57.7%,年均风速和起沙风频率的减少对沙尘暴频率减少的贡献率分别为41.3%和58.7%;大风沙尘天气可能使大气中粗、细颗粒物总量均有所增加,但细颗粒物增加更明显.

Based on the formulas recommended by the U.S.Environmental Protection Agency,the dust emission rates trend and impact factors of PM50 and PM30 were analyzed.Both the dust emission rates and the dust storm frequency decreased significantly during the period from 1960 to 2008 in the Taklimakan Desert;and the finer dust possessed more significant decreasing emission rate.The dust emission rates in the early 21th in Taklimakan desert decreased by 65.01% to 85.14% compared to that in 1960s.The contribution of mean wind velocity decreasing and precipitation increasing to the decrease of PM50 emission rate was 37.8% and 62.2% respectively;the decrease of mean wind velocity and blown sand winds frequency,and the increase of precipitation contribution to the decrease of PM30 emission rate was 9.1%,33.2%,and 57.7% respectively;the decrease of mean wind velocity and blown sand winds contribution to the decrease of dust storm frequency was 41.3% and 58.7% respectively.The total amount both the coarse and fine particles will increase in atmosphere during the windy weather,but the latter had a more obvious trend.