The Near-surface Horizontal Buoyancy Flux in a Highly Stratified Region, Kattegat

A one-dimensional model was used to evaluate the role of wind mixing and a horizontal buoyancy flux on the stratification of the upper 5–10 m in Kattegat at the entrance to the Baltic Sea estuary. The horizontal buoyancy flux in the upper 5–10 m is shown to cause a stabilization of an order of magnitude equal to wind mixing. This buoyancy flux is caused by pulses of large volumes of less salty Baltic Proper water periodically entering Kattegat. When spread over Kattegat, these pulses create stratification within the upper 5 m that typically lasts for 4 days. After stratified periods, the upper 5 m become homogeneous for a day or two before the stratification is re-established. Stratification of the upper 10 m typically lasts for 10–15 days.