A modeling study of tropical cyclone suppression during the AEROSE 2009: Case study of Ana

The northern Atlantic basin was characterized by a relatively weak hurricane activity during the summer of 2009. Although hurricane activity across the Atlantic Ocean has been linked to the El Nino Southern Oscillation, the influence of intraseasonal systems such as the Saharan Air Layer and enhanced vertical wind shear associated with African jets are less understood. Taking advantage of unique observation datasets collected across the tropical Atlantic Ocean during the Aerosol and Ocean Science Expedition (AEROSE) 2009, the WRF-ARW model was run in operational mode to investigate the meteorological factors that contributed to the first weakening of TS Ana. Preliminary results showed the fidelity of the model in forecasting the large-scale circulation and thermodynamic structure of the tropical atmosphere. Furthermore, model runs during the first four days of TS Ana suggest the importance of upper-level wind shear, interaction of the cloud system with the SAL, and weak sea-surface-temperature on storm development.