Recent studies show that Saharan dust can exert substantial radiative and microphysical effects on the weather and regional climate. Moreover, the potential impacts of Saharan dust on the genesis and intensification of tropical cyclones (TCs) remain unclear. In this project, the influences of Saharan dust on the Atlantic regional climate and the genesis of TCs are investigated in the hurricane seasons of 2005 and 2006, which represent hurricane active years and inactive years, respectively. The atmospheric stand-alone version of the Community Earth System Model version 1.0.4 (CESM1.0.4), CAM5.1, is used to simulate the climate condition in full (dust) and none dust (non-dust) emission from the continents. Two regions of interest, the Atlantic TC genesis region (GNR, 50W-20W, 5N-15N) and the TC intensification region (ITR, 70W-40W, 15N-30N), are analyzed. Model output proves the important roles of Saharan Dust on the radiative budget, hydrological cycle, and TC genesis. Dust perturbs the large-scale circulation that moves the Inter Tropical Convective Zone (ITCZ) northward, enhances the West African monsoon, changes the cloud fraction, and perturbs the regional longwave and shortwave radiations. Dust favors the genesis of TCs thermodynamically by increasing the mid-level moisture in the GNR. On the other hand, the TC formation is suppressed by dust through increasing wind shear and decreasing low-level vorticity in the GNR. It is likely that the TC genesis region shifts northward with the ITCZ.
- Zhang, Renyi University Distinguished Professor