青藏高原平流层臭氧和气溶胶的变化趋势研究

通过分析SAGEⅡ资料,发现青藏高原平流层臭氧存在递减趋势,15—50 km臭氧的变化对臭氧总量变化贡献最大,其中25—50 km和15—25 km两层的贡献大致相当。通过青藏高原和中国东部地区平流层臭氧变化的对比,清楚地看出:两地臭氧总量变化的差异主要是由于在15—25 km臭氧变化不同所致。5—7月臭氧变化趋势的情况与年平均的变化类似,两地臭氧变化的差异主要在平流层低层,即15—25 km。青藏高原平流层气溶胶面密度的时间变化序列显示:大的火山喷发对青藏高原平流层气溶胶具有重要影响,其影响可持续6年左右。从1997年至今,青藏高原18—25 km气溶胶面密度增加,最大的增长出现在23 km,每年大约增长4%—5%。而在16—17 km气溶胶的面密度出现减少趋势。与此同时,在37 km以下,青藏高原的温度出现递减的趋势,而且其递减速度比中国东部地区快;在37—50 km,温度出现增加的趋势,青藏高原的增温也比中国东部地区快。青藏高原平流层低层气溶胶的增加和温度的降低都将增强该区域非均相反应的作用。

TRENDS OF STRATOSPHERIC OZONE AND AEROSOLS OVER TIBETAN PLATEAU

It is found from the analysis of SAGE II dataset that there was a decreasing trend of stratospheric ozone over the Tibetan Plateau(TP) in 1985-2004.The changes in total column ozone mainly resulted from the ozone from 15 km to 50 km,wherein the role of the ozone from 25 km to 50 km was almost equal to that from 15 km to 25 km.From comparing the ozone changes between the TP and east part of China(ECHN),it can be clearly seen that the differences between the two areas was mostly ascribed to the difference of ozone changes from 15 km to 25 km.The trend for May to July was similar to that for yearly average,and the difference of trends between the two areas also mainly occurred in the low stratosphere from 15 km to 25 km.Time serials of aerosol area density over the TP show that big volcanic eruptions significantly affected the stratospheric aerosols over the TP, and the influences continuously lasted for about 6 years.Since 1997 the aerosol area density has increased between 18 km and 25 km over the TP,with a maximum growth of about 4% to 5% per year at 23 km,but decreased between 16 km and 17 km.Meanwhile,the temperature below 37 km has decreased over the TP,and it decreased faster over the TP than over the ECHN.From 37 km to 50 km,the temperature has increased,and it increased faster over the TP than over the ECHN.Both the aerosol increase and temperature decrease in the low stratosphere over the TP would all enhance the role of heterogeneous reactions.