Influence of ship emitted sulfur and carbonaceous aerosols on East Asian climate in summer

Abstract

Ship emissions may have significant influences on regional climates with growing trade around the world. Therefore, an updated regional climate model with comprehensive cloud microphysics schemes is employed to investigate the effects of shipping sulfate and primary carbonaceous aerosols on the East Asian summer climate. Investigations indicate that ship emissions have substantial influences on air quality, the radiative energy budget and regional climate change in East Asia in summer. They would directly result in an increment in aerosol surface concentration by at least 10% around the coasts and optical depth by 0.03 over East Asia, which considerably increases the cloud droplet numbers along ship lanes. Subsequently, a very negative instantaneous radiative forcing (>1.5 W/m²) at the surface is exerted, and then the dipoles of anti-cyclone and convergence anomalies might occur from the Bay of Bengal to northeast Asia due to shipping aerosols. These thermal-dynamic responses could further affect cloud formation, hence inducing heterogeneous and nonlocal responses of radiation, air temperature and precipitation. Both cloud optical depth and fraction are likely increased in southwestern to northern China but decreased in parts of southern China and northeastern Asia through shipping aerosols interacting with radiation and clouds. As a result, surface cooling and wetting (warming and drying) are found in the region with positive (negative) cloud change. The absorption of shipping BC to solar radiation could yield a substantial warming tendency, which might have significant contributions to the climate responses in central to northern China.