Observations and Modeling of the Sea Breeze with the Return Current

Data from a wind profiler are used to investigate the vertical structure of the sea breeze with the accompanying return current at the North Sea coast in the Netherlands for three sea-breeze cases. In one of the cases, with a very weak and constant background flow, the return current mass flux approximately compensates for the sea-breeze mass flux. To study the sea breeze with the accompanying return current, a simple two-dimensional mesoscale model is constructed. It is found that the sea breeze as well as the return current of the three cases in this study are simulated well by the model. In the case mentioned above, the model indicates an overcompensation of the sea breeze by the return current. It is found that the latter is a function of the initial vertical temperature profile and the depth of the boundary layer, and that it can be as much as 30%. The overcompensation is balanced by a mass flow (in the sea-breeze direction) at a larger height (“return–return current”). As such, a three-layer structure for the sea breeze becomes evident.