Effects of surface vegetation on the intensity of East Asian summer monsoon as revealed by observation and model experiments

Abstract

This study investigates the effects of surface vegetation density on the East Asian summer monsoon (EASM). The analysis using observation and reanalysis data reveals that the increase of vegetation drives a dipole pattern in the precipitation anomalies where the precipitation in Northeast Asia tends to increase, whereas the precipitation in southern China and East China Sea tends to decrease. The model sensitivity experiments confirm the mechanism of regional monsoon circulation changed by changes in surface vegetation density, in which enhanced vegetation leads to an increase of surface evapotranspiration and a decrease of surface temperature over land. The decrease in precipitation over southern China and East China Sea is attributed to the slow-down of EASM circulation due to the reduction in thermal contrast between the continent and the ocean. The results suggest that the surface vegetation can change the local thermal conditions and induce the dynamical process in broader scale to change the precipitation response.