Simulation of direct effects of black carbon aerosol on temperature and hydrological cycle in Asia by a Regional Climate Model

Abstract

The simulation of direct radiative effect of black carbon (BC) aerosol over Asia is carried out with application of Regional Climate Model RegCM3 over the period of 1993–2003 based on BC emission inventory in 2000. Major findings are as follows. The column burden of BC exceeds 1 mg/m2 in central, eastern, and southern China with the highest value of 2.5 mg/m2 over Sichuan Basin of China, and is of 1–2 mg/m2 in India subcontinent. The column averaged advection field of BC shows an eastward tendency in north of 20° N, whereas an opposite trend is found in south of 10° N. Off-line radiative forcing (RF) induced by BC, which is due to direct absorption or scattering of BC, is positive at the top of the atmosphere (TOA), while maximum effect is found over Sichuan Basin. The RF is of 1–1.5 W/m2 in areas such as the middle and low reaches of the Yangtze River, East China Sea, South China Sea, Indo-China Peninsula and most parts of Indian subcontinent. Surface RF is found to be negative and its absolute value is larger than that at TOA. Based on simulation results, BC’s impacts on temperature, stratification stability, water vapor, precipitation and evaporation etc., are primarily characterized by cold-and-wet change in southern and northwest China, cold-and-dry change in northern and northeast China, warm-and-wet change of India subcontinent, as well as warm-and-dry change of Central Asia.