Abstract
Climate variability in monsoon and arid regions attributable to dynamic vegetation is investigated by using NCAR’s Community Earth System Model (CESM) with the Dynamic Global Vegetation Model. Two present climate simulations, one with dynamic and the other with fixed vegetation cover, are carried out. A comparative analysis of the two simulations reveals that climate in monsoon and arid regions show different responses to the dynamic vegetation. On hemispheric scale, precipitation mainly exhibits increase in the Northern Hemisphere and decrease in the Southern Hemisphere in response to dynamic vegetation, and the surface temperature shows consistent decrease. On regional scale, the precipitation decrease caused by dynamic vegetation is the main trend in the monsoon regions except the Asian monsoon region, whereas the responses of precipitation to vegetation change is weak in the arid regions relative to monsoon regions. The surface temperature increased significantly due to dynamic vegetation only in the boreal winter Asian monsoon region, whereas the rest of monsoon regions and the arid regions mainly shows decreased surface temperature. Therefore, climate variability in the Asian monsoon region is obviously different from other regions. Further analysis shows that the dynamic vegetation can modulate the variations of the east-west sea level pressure gradient and the lower-level meridional winds in East Asia, and strengthen (weaken) East Asian summer (winter) monsoon. Mechanistic analysis reveals that the difference in hemispheric and regional climate variations may be due to the changes of dynamic vegetation-induced moisture flux and net surface radiative forcing.
