2009b: Aerosol-Induced Large-Scale Variability in Precipitation over the Tropical Atlantic

• Main Authors: Jingfeng Huang, Chidong Zhang, Joseph, M. Prospero
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: North Atlantic; North Atlantic oscillation
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.685.3716; http://www.rsmas.miami.edu/assets/pdfs/mac/fac/Prospero/Publications/Huang_etal_JClim22_2009.pdf

Multiyear satellite observations are used to document a relationship between the large-scale variability in precipitation over the tropical Atlantic and aerosol traced toAfrican sources. During boreal winter and spring there is a significant reduction in precipitation south of the Atlantic marine intertropical convergence zone (ITCZ) during months when aerosol concentrations are anomalously high over a large domain of the tropical Atlantic Ocean. This reduction cannot be linearly attributed to known climate factors such as El Niño– SouthernOscillation, the North Atlantic Oscillation, and zonal andmeridional modes of tropical Atlantic sea surface temperature or to meteorological factors such as water vapor. The fractional variance in precipitation related to aerosol is about 12 % of the total interannual variance, which is of the same order of magnitude as that related to each of the known climate and weather factors. A backward trajectory analysis confirms the African origin of aerosols that directly affect the changes in precipitation. The reduction inmean precipitation mainly comes from decreases in moderate rain rates (10–20 mm day21), while light rain (,10 mm day21) can fluctuate in the opposite direction. The results cannot be readily explained in terms of wet deposition or uncertainties in satellite retrievals, and suggest that the observations demonstrate clearly identifiable effects of African aerosol on large-scale variability in precipitation in the tropical Atlantic region. 1.