The Use of AVHRR Satellite Data for Estimating Spatially Varying Critical Wind Stress in Florida Bay

Varis Ransibrahmanakul, Richard P. Stumpf

Abstract


Critical bottom stress for resuspension and sediment settling are essential parameters in determining and modeling sediment transport in shallow water. However, these parameters are often assumed spatially uniform due to the problem of obtaining the necessary data. This paper presents a method for obtaining spatially varying critical wind stress and spatially varying change in concentration by settling in Florida Bay. As a means to get critical wind stress, a simple model for estimating suspended sediment concentration was implemented. The model has one time-dependent input, wind stress; and four time-independent inputs: maximum concentration, minimum concentration, temporal scale of sediment settling decay, and critical wind stress. Maximum concentration, minimum concentration, and temporal scale of sediment concentration settling decay were derived from time series of Advanced Very High Resolution Radiometer (AVHRR). Temporal scale of settling was determined using a simple model of concentration change with wind mixing of the water column. The critical wind stress for resuspension was obtained by optimizing the error between the model's results and the observed concentrations. The modeled sediment concentration performed best in areas where wind was the only dominant forcing agent rather than in areas where advection may also play a significant role. Incorporating this approach into standard modeling of sediment circulation can provide better information on the occurrence and potential for resuspension.


Keywords


Remote sensing; wind stress; AVHRR; sediment resuspension; Florida Bay

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