%0 Journal Article
%T Multi-satellite aerosol observations in the vicinity of clouds
%A T. V¨¢rnai
%A A. Marshak
%A W. Yang
%J Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD)
%D 2013
%I Copernicus Publications
%X Improved characterization of aerosol properties in the vicinity of clouds is important for better understanding two critical aspects of climate: aerosol¨Ccloud interactions and the direct radiative effect of aerosols. Satellite measurements have provided important insights into aerosol properties near clouds, but also suggested that the observations can be affected by 3-D radiative processes and instrument blurring not considered in current data interpretation methods. This study examines systematic cloud-related changes in particle properties and radiation fields that influence satellite measurements of aerosols in the vicinity of low-level maritime clouds. For this, the paper presents a statistical analysis of a yearlong global dataset of co-located MODIS and CALIOP observations and theoretical simulations. The results reveal that CALIOP-observed aerosol particle size and optical thickness, and MODIS-observed solar reflectance increase systematically in a wide transition zone around clouds. It is estimated that near-cloud changes in particle populations ¨C including both aerosols and undetected cloud particles ¨C are responsible for roughly two thirds of the observed increase in 0.55 ¦Ìm MODIS reflectance. The results also indicate that 3-D radiative processes significantly contribute to near-cloud reflectance enhancements, while instrument blurring contributes significantly only within 1 km from clouds and then quickly diminishes with distance from clouds.
%U http://www.atmos-chem-phys.net/13/3899/2013/acp-13-3899-2013.html