THE DIRECT EFFECTS OF AEROSOLS AND DECADAL VARIATION OF GLOBAL SEA SURFACE TEMPERATURE ON THE EAST ASIAN SUMMER PRECIPITATION IN CAM3.0

• Published in: Journal of Tropical Meteorology Vol. 23; no. 2; pp. 217 - 228
• Main Author: 刘超 胡海波 张媛 杨修群
• Format: Journal Article
• Language: English
• Published: Guangzhou Guangzhou Institute of Tropical & Marine Meteorology 01.06.2017
• Subjects: Aerosol concentrations; Aerosols; Anomalies; Atmosphere; Atmospheric aerosols; Atmospheric precipitations; Black carbon; Black carbon aerosols; Carbon; Carbon aerosols; Carbon black; Climate; Climate effects; Coasts; Convection; Drought; Experiments; General circulation models; Global temperatures; Heavy rainfall; Precipitation; Rain; Rainfall; Rainfall distribution; Scattering; Sea surface; Sea surface temperature; Sinking; Sorption; Sulfates; Summer; Summer precipitation; Surface temperature; Temperature; Temperature effects; Troposphere; Wind; Wind fields; Yangtze River Delta; East Asia
• ISSN: 1006-8775
• DOI: 10.16555/j.1006-8775.2017.02.010

Using the CAM3.0 model, we investigated the respective effects of aerosol concentration increasing and decadal variation of global sea surface temperature（SST） around year 1976/77 on the East Asian precipitation in boreal summer. By doubling the concentration of the sulfate aerosol and black carbon aerosol separately and synchronously in East Asia（100-150 °E, 20-50 °N）, the climate effects of these aerosols are specifically investigated. The results show that both the decadal SST changing and aerosol concentration increasing could lead to rainfall decreasing in the center of East Asia, but increasing in the regions along southeast coast areas of China. However, the different patterns of rainfall over ocean and lower wind field over Asian continent between aerosol experiments and SST experiments in CAM3.0 indicate the presence of different mechanisms. In the increased aerosol concentration experiments, scattering effect is the main climate effect for both sulfate and black carbon aerosols in the Eastern Asian summer. Especially in the increased sulfate aerosol concentration experiment, the climate scattering effect of aerosol leads to the most significant temperature decreasing, sinking convection anomalies and decreased rainfall in the troposphere over the central part of East Asia. However, in an increased black carbon aerosol concentration experiment, weakened sinking convection anomalies exist at the southerly position. This weakened sinking and its compensating rising convection anomalies in the south lead to the heavy rainfall over southeast coast areas of China. When concentrations of both sulfate and black carbon aerosols increase synchronously, the anomalous rainfall distribution is somewhat like that in the increased black carbon concentration aerosol experiment but with less intensity.