基于无人机平台的黑炭垂直变化监测

UAV-based Vertical Profiles of Black Carbon

目的获取对流层内黑炭的垂直分布规律和输送来源。方法在2014年夏天和2015年冬天,通过无人机平台搭载便携式设备来监测临安市高空1000m内黑炭的垂直变化情况。经过2天的试验,总共成功采集了8次试验数据,为了减少统计误差,取300~1000m内每隔100m高度层所测得数据的平均值进行分析。结果地面试验结果表明,上午冬季黑炭的质量浓度几乎是夏季的3倍,但是下午冬季黑炭的质量浓度却略低于夏季。无人机试验结果表明,总体上,日变化情况中,夏季黑炭质量浓度逐渐增加,而冬季黑炭质量浓度逐渐减少。不管是夏季还是冬季,上午黑炭的质量浓度随着高度增加而下降,且降幅较大,冬季上午黑炭的质量浓度要远高于夏季上午,但下午黑炭的质量浓度相似。48h后向轨迹结果表明,夏季300m和1000m处气团来源于上海,且输送轨迹都在长三角区域,输送距离在200km以内;冬季300m和1000m处气团来源于北方地区,且输送距离都在1000km以上。结论通过个例分析,结果表明,冬季早晨黑炭的质量浓度较高,夏季污染物主要来源于近距离输送,但是冬季污染物主要来源于远距离输送。

Objective To study vertical profiles and conveying sources of black carbon in the troposphere.Methods Vertical measurements with unmanned aerial vehicle(UAV)carrying portable sensors were conducted to collect altitude profiles on concentration of BC within 1000 meters in the summer of 2014 and the winter of 2015 in Lin’an,China.In order to reduce statistical error,two days’BC data including eight field experiments was averaged according to altitude.Results The ground test results indicated that the mass concentration of BC in the winter morning was 3 times of that in the summer morning;while the mass concentration of BC in the winter afternoon was less than that in the summer afternoon.The UAV test results showed,during the day,the concentration of BC increased over time during summer and decreased over time during winter.During the morning in both summer and winter,the mass concentration of BC decreased with the increase of height.Moreover,the mass concentration of BC in the winter morning was much larger than that in the summer morning.But the mass concentration of BC in summer afternoon and winter afternoon was similar.The results of 48 h HYSPLIT archive trajectories exhibited that air mass of the summer at 300 m and 1000 m was derived from Shanghai and the conveying distance was within 200 km.That is,all transport paths were in the Yangtze river delta region.However,air mass of the winter at 300 m and 1000 m was dated from northern areas and the conveying distance was beyond 1000 km.Conclusion The case study indicates heavy concentration of BC tends to form in the winter morning.The main source of pollutants in summer is the short distance transport;while the main source of pollutants in winter is the remote transport.