Shallow ocean currents are primarily wind driven. Accurate representation of wind fields, therefore, is crucial to understanding how light-weight, buoyant oil-derived substances move around the Alabama Shelf and Mobile Bay and how they are exchanged between the two water bodies. Average surface wind flow fields in Coastal Alabama change seasonally, with a more westerly flow regime dominant in the cold season and southerly flow prevailing in the warm season. Similarly, wind observations display a distinct diurnal cycle, especially in the warm season when the sea-breeze regime dominates. Using observations collected by weather stations in and around Mobile Bay, a seasonal and diurnally averaged wind-field for the area will be composited. This low-level wind field will serve as an input to ocean modelers to accurately simulate seasonal and diurnal currents in local water bodies.
These average, seasonal flow regimes are frequently interrupted by significant weather features such as tropical storms and cold fronts which bring strong, gusty winds and rapidly changing weather conditions. Winds change quickly both in magnitude and direction as such systems pass through the area. Strong winds can cause overturning of shallow water bodies, causing heavier oil-derived substances, embedded in sediment, to be brought back into suspension or even all the way to the surface. Rapidly changing wind conditions can bring considerable uncertainty in where pollutants may be transported. Using the Weather Research and Forecasting model (WRF) a simulation of a past hurricane (Ivan) will be conducted in order to provide low-level wind fields in extreme conditions. Again, these wind fields will be used by ocean modelers to study the behavior of the ocean currents in extreme weather events.