2018 Volume 96 Issue 4 Pages 391-403
The climate variability in monsoon and arid regions attributable to dynamic vegetation is investigated using NCAR's Community Earth System Model with the Dynamic Global Vegetation Model. Two present climate simulations, one using dynamics and the other using fixed vegetation cover, are carried out. A comparative analysis of the two simulations reveals that the climate in monsoon and arid regions exhibits different responses to dynamic vegetation. On the hemispheric scale, precipitation mainly increases in the Northern Hemisphere and decreases in the Southern Hemisphere in response to dynamic vegetation, while the surface temperature exhibits a consistent decrease. On the regional scale, precipitation decreases caused by dynamic vegetation are the main trend in monsoon regions except for the Asian monsoon region, while precipitation responses to vegetation change are weak in arid regions relative to monsoon regions. The surface temperature increases significantly because of dynamic vegetation only in the boreal winter Asian monsoon region, while the rest of the monsoon and arid regions mainly exhibit reduced surface temperatures. Therefore, the climate variability in the Asian monsoon region is clearly different from the other regions. Further analysis shows that dynamic vegetation can modulate variations in the east–west sea-level pressure gradient and lower-level meridional winds in East Asia, and it can strengthen (weaken) the East Asian summer (winter) monsoon. Mechanistic analysis reveals that the difference in hemispheric and regional climate variations may be due to changes in the dynamic vegetation-induced moisture flux and net surface radiative forcing.