气溶胶对东亚冬季风影响的数值模拟

Simulations of Aerosol Influences on the East Asian Winter Monsoon

利用NCAR/UCAR CAM5.1模式研究气溶胶对东亚冬季风的影响。模式从1991-2010年运行20年,取2001-2010年冬季的结果。模式结果可以较好地再现东亚冬季风的主要特征。试验结果表明:气溶胶增加使我国东南部地区和东北亚地区(35°～55°N,115°～150°E)冬季风减弱,同时,造成我国东南部地区降水减少。其中,热源热汇的变化和无辐散风减弱为主要原因。气溶胶增加改变了大气热源的分布,造成在我国东南部地区热源减弱,热汇加强;我国东北地区热汇减弱,日本列岛热源加强;气溶胶增加使这些区域全位能的产生减弱,消耗加强。同时,凝结潜热的变化主要影响热源和热汇,其中大尺度过程产生的凝结潜热变化起主要作用。在我国东南部和东北亚地区辐散风动能向全位能的转换增加,造成辐散风减弱。故该区域辐散风向无辐散风的转换减弱,导致无辐散风减弱,最终造成东亚冬季风减弱。

As the most active circulation system in the northern hemisphere in winter, the east Asian winter monsoon has an important influence on weather and climate in east Asia. In recent years, the concentration of aerosol keeps increasing, and the east Asian winter monsoon is influenced by its change. Numerical simulation experiments are carried out to study the influence using NCAR/UCAR CAM5. 1 model, adopting the aerosol emission source of years of 2000 and 1850 each, and models are run from 1991 to 2010 for 20 years. Results from 2001 to 2010 in winter are analyzed.It is found that the increase of aerosols reduces the winter monsoon in the southeastern China and northeastern Asia（35°-55°N, 115°-150°E）. At the same time, causing precipitation to reduce and temperature to drop in the southeastern region of China. The increase of aerosols changes the distribution of atmospheric heat sources, resulting in the heat source on the southeastern region of China weakened, and heat sinks strengthened; heat sinks in the northeastern China are weakened and heat sources on Japan Islands are strengthened. The production of potential energy is weakened, and the consumption is enhanced. Another result is that the change of heat source and heat sink is mainly caused by the change of latent heat of condensation, and the change of latent heat generated by large scale process plays a key role.Besides, in the southeastern and northeastern regions of China, the conversion from the divergent wind kinetic energy into the full potential energy increases, resulting in the divergent wind weakening. At the same time, the conversion from the divergent wind into the non-divergent wind in this area is weakened,causing the weakening of the non-divergent wind, and finally resulting in the weakening of east Asian winter monsoon. Through direct and indirect climate effects, aerosol affects heat balance and precipitation,changes the distribution of atmospheric heat sources and thermal structures, leading to changes in the full potential energy and kinetic energy as well as the transformation between them, and ultimately causing the weakening of the east Asian winter monsoon. The impact of aerosol increase on east Asian winter monsoon cannot be ignored.