Impacts of the atmospheric apparent heat source over the Tibetan Plateau on summertime ozone vertical distributions over Lhasa

Abstract

The Tibetan Plateau (TP) is an area sensitive to climate change, where the ozone distribution affects the atmospheric environment of the TP and its surrounding regions. The relatively low total column ozone over the TP in boreal summer and its spatiotemporal variations have received extensive attention. In this study, five-year balloon-borne measurements of ozone over Lhasa in boreal summer are used to investigate the influences of the apparent heat source (Q1) on the ozone vertical structure over the plateau. The mechanisms for the above processes are also explored. The results show that the tropospheric ozone mixing ratio over Lhasa decreases when the total atmospheric Q1 in the troposphere over the TP is relatively high. Strengthened ascending motions are accompanied by enhanced Q1 over the main TP region. Consequently, the tropospheric ozone mixing ratio over Lhasa decreases when Q1 is higher in summer, which is attributed to the upward transport of the ozone-poor surface air.摘要青藏高原(TP)是一个对气候变化敏感的地区, 其上空的臭氧分布影响着青藏高原及其周边地区的大气环境.北半球夏季青藏高原上空臭氧柱总量相对较低的现象, 及其时空变化受到广泛关注.本研究利用北半球夏季5年的拉萨上空臭氧的气球测量数据, 研究高原上空大气视热源(Q1)对臭氧垂直分布的影响并探讨了该过程的机制.结果表明, 当TP上空对流层整体的Q1相对较高时, 拉萨上空对流层臭氧浓度下降.大气更强的上升运动伴随着TP主体区域上空的Q1的增大.因此, 当夏季Q1较高时, 由于近地表低浓度臭氧空气向上输送, 拉萨上空的对流层臭氧浓度下降.