9A.5 Sensitivity of Sahelian Precipitation to North African Dust Aerosol under ENSO Variability: Dynamics, Variability and Feedbacks in NASA Models and Observations

Wednesday, 10 January 2018: 9:30 AM
616 AB (Hilton) (Austin, Texas)
Asha Jordan, Johns Hopkins Univ., Baltimore, MD; and B. F. Zaitchik, A. Gnanadesikan, D. Kim, M. Chin, and H. S. Badr

North Africa is the world’s largest source of mineral dust, and this dust has potentially significant impacts on precipitation. Bounded by the Sahara Desert to the north and the Sahelian Savannah to the south, the Sahel experiences high interannual rainfall variability and a short rainy season during the boreal summer months. Observation-based data for the past three decades indicates a reduced dust emission trend, together with an increase in greening and surface roughness within the Sahel. There is no consensus in published, climate modeling studies regarding the sign or magnitude of dust impacts on rainfall in either the highly climate sensitive Sahel region of North Africa or the neighboring Tropical Atlantic Ocean. Inconsistency of model estimates drives future climate projections for the region that are highly varied and uncertain. We use the NASA-Unified Weather Research and Forecasting (NU-WRF) model to quantify the interaction and feedback between desert dust aerosol and Sahelian precipitation. At fine spatial resolution we resolve changes to mesoscale atmospheric circulation patterns due to dust, for representative phases of El Niño-Southern Oscillation (ENSO). The NU-WRF regional earth system model offers both advanced land surface data and dust emission modeling, and resolvable detail of the mechanisms of the impact of Saharan dust. This presentation will offer a quantitative analysis of differences in radiation budget, energy and moisture fluxes, and atmospheric dynamics due to desert dust aerosol over the Sahel.
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