Modeling Saharan desert dust radiative effects on clouds

Abstract

This work aims at studying the Saharan desert dust storm effects on clouds. This is done through the investigation of the possible modifications that mineral desert dust aerosols may exert on clouds, modifying their properties and also through the estimation of the cloud radiative forcing in the presence of this type of aerosols, during strong desert dust events that occurred in the end of May 2006 and in the beginning of September 2007. The assessment of the cloud radiative forcing is made at a regional scale both at the top of the atmosphere (TOA) and at the surface levels. The results are obtained from numerical simulations with a mesoscale atmospheric model (MesoNH) over Portugal area and nearby Atlantic Ocean. From the results obtained it is possible to observe that, for all days under study, a cooling effect is always found both at the TOA and surface levels. Also, for these two levels and for clouds developing in a dusty atmosphere, a more pronounced cooling effect (more negative cloud radiative forcing values) is found compared with the corresponding cloud radiative forcing values for clouds developing in a dust free atmosphere.