基于CALIOP探测的京津冀地区气溶胶垂直分布特征

利用2011—2015年星载激光雷达(CALIOP)探测资料分析京津冀地区气溶胶消光系数(AEC)的垂直分布,AEC表征了气溶胶的浓度水平。结果表明:AEC的垂直分布季节变化显著,2 km以下尤为明显;整层气溶胶光学厚度(AOD)在夏季(0.7)高于其他季节,湿度对AEC产生较大的影响;而500 m以下低层的AEC体现的特征与之相反,冬季最大(0.65 km~(-1)),春夏季较小(0.25 km~(-1))。夏秋季低层AEC存在较大昼夜差异,夜间最大为0.65 km~(-1),是白天的2.5倍,低层较大的相对湿度昼夜变化成为消光系数巨大差异的主因。南北向贯穿京津冀地区垂直剖面上AEC的分布显示,在夏季夜间,气溶胶浓度水平在南部地区的低层较高,而在其他季节并没有体现出明显的南北差异。

CHARACTERISTIC OF VERTICAL AEROSOL DISTRIBUTION OVER JING-JIN-JI AREA OBSERVED BY CALIOP

Vertical distribution of aerosol extinction coefficient (AEC) representing aerosol concentration level was investigated using satellite observation obtained by CALIOP over Jing-Jin-Ji (JJJ) area during 2011-2015.Results showed that vertical distribution of AEC had a distinct seasonal variability,especially below 2 km in altitude.Aerosol optical depth (AOD) integrated from full-layer AEC also varied significantly with seasons.AOD was much higher in summer (0.7) than that in other seasons,which was substantially influenced by ambient relative humidity.However,the opposite characteristic of low-layer AEC was observed below 500 m with the highest value of 0.65 km-1 in winter and smaller ones in spring and summer.There was a remarkably difference of low-layer AEC between day and night in summer and autumn with the maximum of 0.65 km-1 after midnight,which was 2.5 times in the early afternoon.The large day-night discrepancy of low-layer relative humidity was the major cause for the contrast of extinction coefficient.Zonal vertical distribution of AEC cross section through JJJ area showed that the level of aerosol concentration was higher in low-layer over south part of the region in summer night,while in other seasons,no obvious south-north differences were observed.