Radiative impacts from biomass burning in the presence of clouds during boreal spring in southeast Asia

Abstract

The impact of smoke aerosols generated from biomass burning activities in Southeast Asia on the total (i.e., direct and indirect effects) reflected solar and emitted thermal radiation from clouds was investigated using satellite data. We combine narrowband radiance measurements, from ultraviolet to near-infrared wavelengths (e.g., SeaWiFS and TOMS), with broadband irradiance measurements (e.g., CERES) to quantify how smoke aerosols modulate the cloud radiative forcing. In Southeast Asia, our results reveal that smoke is frequently present over large areas of cloud-covered regions during boreal spring. The reflected solar (emitted thermal) radiation from clouds due to smoke aerosols can be reduced (enhanced) by as much as 100 (20) W m−2 over the month of March 2000. We also found that the reduction in cloud spectral reflectance at 670 nm is large enough to lead to significant errors in retrieving cloud properties (e.g., optical thickness and effective radius) from current satellite measurements, such as AVHRR and MODIS.