Water Dynamics above the Sloping Bottom due to an Intense Summer Heating

I. P. Chubarenko, V. V. Afon, V. Ya. Chugaevich, and V. A. Krechik

Considered is the water exchange in the coastal zone of natural reservoirs induced as a result of the differential heating of water above the sloping bottom. The laboratory experiment data and the constructed simple analytic model demonstrate that the main reason for the motions is the hydrostatic pressure difference in the area above the slope. It is demonstrated for different types of vertical stratification that the pressure difference maximum is reached at the depth of about 0.4D (D is the depth of the heated layer in the deep part). The respective current is directed to the shore and is a driving element of the whole circulation of water including its forced ascend along the slope, the free surface level increase, and the formation of the compensatory offshore current in the upper layers. The analysis of in situ observational data in the coastal zone of the Baltic Sea at the intensive heating in July 2006 corroborates the obtained regularities indicating that the coastal heating favors the formation of upwelling along the slope.