Possible Effects Of Natural Vegetation Restoration On The Regional Climate Of East Asia

Land use cover change(LUCC)is one of the important external forcing factors of the climate change.This paper explored the possible distribution of natural vegetation in east Asian domain and its impact on climate using the dynamic vegetation model CLM4-CNDV,the regional climate model RegCM4.6-CLM3.5 and the global climate model CAM4.The related physical mechanisms between vegetation restoration and regional climate change are discussed.Climate responses in this area to the vegetation restoration in and out of the East Asian domain are compared based on the simulated results using different type of lateral boundary conditions.The results are as follows:(1)The RegCM4.6-CLM3.5 model,which is forced by the lateral boundary conditions of CAM model,can simulate the spatial distribution of regional air temperature and precipitation in China well,and it has a very high consistency reflecting the spatial pattern of 2-meter temperature and precipitation in China and East Asia.The model simulated better for winter temperature than for summer,and better for summer precipitation than for winter.The spatial pattern of temperature is better simulated than that of precipitation.The regional atmospheric circulation can be simulated well also.(2)Under current climate conditions,the crop areas in the north,northeast,North China Plain and part of Sichuan Basin are probably distributed by bare soil;in the southeast of East Asia and the north of the Mongolian Plateau mainly by woodland;in the Sichuan Basin and Shandong Peninsula mainly by shrubs;and in the northeast,southeast coastal areas and the middle and lower reaches of the Yangtze River mainly by grasslands.(3)The restoration of crop areas by natural vegetation takes significant impact on the regional climate.The increase in evapotranspiration caused by the increase in vegetation leaf area index in most parts of eastern Asia led to an increase in summer precipitation and a significant decrease in temperature.The vegetation leaf area index decreased in North China,Sichuan Basin,and the central plains of Guangdong,accompanied by a significant decrease in summer precipitation and an increase in temperature in the region.The climate change in the Mongolian Plateau is not only affected by the regional vegetation cover change,but also may be related to the atmospheric circulation adjustment caused by the vegetation change in India and the southeast of China.As a result,the winter temperature in the western part of the Mongolian Plateau decreases,while the summer temperature in the eastern part increases,and the summer precipitation decreases significantly.(4)Three experiments using different sets of lateral boundary conditions,which is derived by using vegetation restoration in and out of the domain,are conducted.Results show that the influence on summer temperature is less than on winter due to different type of lateral boundary conditions.And summer precipitation in the southeastern Asia could be different using different boundary conditions.The change of summer temperature is mainly related to the change of net radiation,while the change of in winter temperature in southeastern China is mostly related to the change of evapotranspiration.The warming due to reduced evaporative cooling exceeds the warming due to the radiative effect of increased surface albedo.