Aerosol direct radiative effect of smoke over clouds over the southeast Atlantic Ocean from 2006 to 2009
de Graaf, M
Geophysical Research Letters
American Geophysical Union
This is the final version of the article. Available from the American Geophysical Union via the DOI in this record.
The aerosol direct radiative effect (DRE) of African smoke was analyzed in cloud scenes over the southeast Atlantic Ocean, using Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) satellite observations and Hadley Centre Global Environmental Model version 2 (HadGEM2) climate model simulations. The observed mean DRE was about 30–35 W m−2 in August and September 2006–2009. In some years, short episodes of high-aerosol DRE can be observed, due to high-aerosol loadings, while in other years the loadings are lower but more prolonged. Climate models that use evenly distributed monthly averaged emission fields will not reproduce these high-aerosol loadings. Furthermore, the simulated monthly mean aerosol DRE in HadGEM2 is only about6Wm−2 in August. The difference with SCIAMACHY mean observations can be partly explained by an underestimation of the aerosol absorption Ångström exponent in the ultraviolet. However, the subsequent increase of aerosol DRE simulation by about 20% is not enough to explain the observed discrepancy between simulations and observations.
This work was funded by the Netherlands Space Office, project AERFORCE (ALW-GO/12-32). SCIAMACHY L1B reflectances used for this study are freely provided by ESA (www.sciamachy.org).
Geophysical Research Letters, 2014, Vol. 41, pp. 7723 - 7730