The impact of the direct effects of sulfate and black carbon aerosols on the subseasonal march of the East Asian subtropical summer monsoon Journal of Geophysical Research: Atmospheres

Aerosol emissions have rapidly increased in East Asia since the late 1970s. During the same period, the East Asian summer monsoon has shown a weakening trend. In this work, the direct effects (DE) of sulfate and black carbon (BC) aerosols on the subseasonal (pentad mean) march of the East Asian subtropical summer monsoon(EASSM) are investigated usin g an interactive global climate-chemistry mo del. The simulation results suggest that the DE of sulfate aerosols have a notable effect on the coo ling of the low troposphere across the continent in spring and autumn, hence, changing the time of the seasonal transition of the zonal land-sea thermal contrast (ZTC). TheDE of BC result in cooling of the low troposphere and hea ting of the middle troposphere, leading to a different impact than that caused by sulfates. The cooling of the su rface and troposphere by sulfates leads to a delay in the warming of East Asian continent in sprin g and the EASSM onset time; it also accelerates the process of the continent