Some characteristics of fine structure and microstructure of Baltic Sea waters

It is generally agreed that fine structure and microstructure are usually beyond the resolution of numerical models. Nevertheless, corresponding processes have a considerable influence on water dynamics and exchanges in the Baltic Sea. Measurements of fine structure were carried out with the scanning CTD probe. Microstructure measurements were performed by towing a system with fast-response velocity, conductivity, and temperature sensors. Bottom turbulence was investigated with the Acoustic Doppler Velocimeter. Domains of high mixing and stining activity were revealed by means of high-resolution profiling on temperature and salinity transects. These domains were found near inhomogeneities of bottom relief such as the Słupsk Sill, the bottom elevation on eastern boundary of the Słupsk Furrow and in areas of ray concentration of quasi-inertial internal waves. Data on transects with manifestations of convection provide an evidence of the non-uniform distribution of turbulence in the upper layer. A bottom turbulence patch with duration of about 2 hours was registered over the slope of the Gotland Deep. The rate of turbulent energy dissipation is about ]105cm2/s3. In the area of Hamrarne and Słupsk Sill, horizontal scales of turbulent patches are between O(10m) and 0(100 m). All obtained data testify the high level of turbulent intermittency, so probability of detecting turbulent patches is high.