The Direct Radiative Effects of Aerosols over Southeast Asia based on Satellite Observations and Modelling Calculations

The influence of aerosols have been suggested as one of the important reasons for climate change over Southeast Asia (SE Asia, 15S~35N and 75E~155E). Hence, quantification efforts on identifying the impacts of aerosols on regional climate are quite necessary, especially for improvement of the accuracy of climate models. Using the Moderate Resolution Imaging Spectroradiometer (MODIS), Clouds and the Earth's Radiant Energy System (CERES) instrument, and Four-stream Radiative Transfer Models, we provide quantitative evaluation of regional cloud-free diurnally averaged shortwave aerosol radiative effects (SWARE) at both Top of Atmosphere (TOA) and Surface (SFC) over the entire SE Asia. The spatial and temporal variations of annual SWARE are mainly estimated based on satellite and ground-based measurements (e.g. AERONET), supplemented by radiative transfer simulations. During the period of 2001 ~ 2010, our results indicate that the diurnally averaged SWARE at the TOA are -6.61±0.48 Wm-2 over land and -5.10±1.29 Wm-2 over ocean, respectively. We also compare observation- and model-based estimates of clear-sky, annual averaged SWARE with statistic results, which shown that model simulations are quantitatively distinct with measurement-based SWARE, even after accounting for cloud contamination. Our results present significant inter-annual variability of the computed aerosol radiative properties, which is extremely large over major emission outflow areas such as SE Asia. This study suggest an integrated system of satellite data, model calculations, ground-based and meteorological data sets to assess aerosols radiative effects on regional earth-atmosphere energy budgets.