Dominant Features and Mechanisms of Estuarine Surface Fronts

Abstract Surface fronts, ubiquitous in estuarine systems, are often hot spots of physical and biogeochemical features. Although a few types of fronts have been studied individually, a more general understanding of the distributions of estuarine surface fronts and the associated mechanisms is lacking. Through comparative analysis, the Hudson, James, Delaware and Mobile Bay estuaries are found to have similar frontal distribution patterns despite of different tides, river discharges and wind forces. In the four estuaries, along‐channel fronts dominate the spatial frontal distribution patterns, and their generation is found to be related to a simple parameter that can be quantified with horizontal velocity, depth and bottom slope. Where there are high values of this parameter, estuarine surface fronts are more likely to occur. The results are expected to be applicable in other partially and strongly stratified channel‐shoal estuaries globally.