亚洲夏季风反气旋中臭氧的化学收支研究

The Asian summer monsoon anticyclone (ASMA) is a dominated atmospheric circulation pattern in the upper troposphere and lower stratosphere (UTLS) of the Northern Hemisphere. The physical, chemical and dynamic processes associate with ASMA may have a large influence on the transport of tropospheric masses to the stratosphere, and thus global atmospheric chemistry and climate change. Recent studies have shown that Asian pollutants can be transported to the anticyclone through deep convection and trapped there during the Asian summer monsoon. Compared to the outside of ASMA, air masses in the ASMA generally have a chemical feature of being poor in ozone and rich in its precursors as well as volatile halocarbons. However, how these accumulated gaseous pollutants affect the chemical budget of ozone within the ASMS is still unclear. With this proposal, we plan to use an atmospheric chemistry-general circulation model (EMAC) with coupled stratosphere and troposphere processes, together with various satellite product, aircraft measurement and ground-based remote sensing observational data, to investigate the temporal-spatial distributions of reactive trace gases, the sources and aging process of air masses, and the effect of catalytic reaction cycles on the ozone chemical budget within the ASMA. The proposed study will be helpful for revealing the chemical transport and variation mechanism of ozone in the UTLS and for further understanding the troposphere-stratosphere interactions during Asian summer monsoon.

亚洲夏季风反气旋是北半球夏季上对流层和下平流层（UTLS）区域主要的大气环流形式，与之相关的物理化学和动力输送过程对对流层-平流层物质输送以及全球大气化学和气候变化有重要影响。近年来的研究发现，亚洲夏季风期间亚洲边界层内的污染物会通过深对流输送至反气旋中，反气旋中的污染气团具有臭氧贫瘠、臭氧前体物和挥发性含卤有机物富有的化学特征。而这些富集的气态污染物如何影响反气旋中臭氧的化学收支，目前尚不清楚。本项目拟采用平流层和对流层过程全耦合的全球大气化学环流模式EMAC，结合各种卫星产品、飞机航测、青藏高原探空和地基遥感观测资料，研究亚洲夏季风反气旋中反应性气体的来源、时空分布特征和各种催化反应循环对臭氧化学收支的影响。项目研究有助于进一步揭示UTLS区域臭氧的化学输送和变化机制，加深平流层-对流层相互作用机理的认识，推动我国在亚洲季风和全球大气化学方面的研究进展。

亚洲夏季风反气旋是北半球夏季上对流层和下平流层（UTLS）区域主要的大气环流形式，与之相关的物理化学和动力输送过程对对流层-平流层物质输送以及全球大气化学和气候变化有重要影响。本项目利用全球大气化学环流模式EMAC，模拟研究了夏季青藏高原及亚洲夏季风区臭氧及其前体物时空分布特征，研究了亚洲夏季风反气旋中臭氧的来源及化学收支。臭氧的平流层和对流层模式源示踪模拟结果表明，反气旋内源自对流层的臭氧浓度明显高于反气旋外的，源自平流层的臭氧浓度的情景则相反，表明相对于反气旋外亚洲夏季风反气旋内的气团更具对流层气团的特征，同时也说明反气旋的存在可以有效地阻止平流层-对流层交换过程。化学收支分析结果显示，亚洲夏季风反气旋内上对流层臭氧化学生成明显高于反气旋外的；在反气旋内青藏高原上对流层臭氧的化学生成要比反气旋内西部的高。本项目的研究结果表明，青藏高原上对流层较高的臭氧净化学生成（最大为7ppv/天）会部分抵消动力输送过程造成的青藏高原臭氧总量低值。由于南亚污染物会输送到青藏高原UTLS区域，随着南亚污染排放的增加，青藏高原及亚洲夏季风区臭氧时空分布如何变化及相应的气候效应怎样，值得进一步深入研究。