Large-Scale Interactions of African Smoke and Dust Aerosols with Tropical/ Subtropical Atmospheric Circulations and Precipitation

African climate is often interpreted as a continental scale phenomenon which could have strong complex remote influences on global atmospheric circulation. The large-scale effect of dust and Biomass burning particles are significant on Earth's radiation energy budget, climate variability, and water cycle, though their magnitude and extent are still not well quantified. In this study, ensemble of the Modern-Era Retrospective Analysis for Research and Applications (MERRA) and the Moderate Resolution Imaging Spectroradiometer (MODIS) data sets for warm season were used to better understand the dynamics of African aerosol-climate interactions and their long-term forcing on atmospheric circulations and water cycle.

From dynamical perspective, smoke and dust particles over southern and northern Africa are strongly correlated with the flow south of the easterly jet in the positive vorticity core at 500-650 hPa. This study suggests that African dust and smoke particles interact with convective systems of the Hadley and zonal circulations in the tropical African region, with possible connections to subtropical flow from Africa to the middle-east in the middle troposphere. From radiation point of view, the range of long-term averaged atmospheric heating due to dust and smoke in the MERRA data-set is from 10 to 35 Wm-2. During warm seasons aerosol optical depth (AOD) of Saharan dust and southern African smoke have a significant positive correlation with precipitation in the Inter-tropical Convergence Zone (ITCZ) which is accompanied by a negative correlation with the low level monsoon jets. These results indicate a significant relationship between African aerosol forcing and precipitation in the ITCZ.