Direct measurements of turbulent momentum, heat and salt fluxes under landfast ice in the Baltic Sea

Measurements of under-ice turbulence were performed using an acoustic three-dimensional current meter with an attached fast-repetition temperature–conductivity sensor at two coastal areas in the Baltic Sea during two winters. Observations covered both the ice-growth and spring-melt periods. The objective of these measurements was to obtain knowledge of under-ice turbulence and oceanic heat and salt fluxes to and from the ice in the coastal fast-ice region using eddy correlation techniques. The maximum observed daily average heat flux was 1 Wm–2, and the maximum for 10 min periods was an order of magnitude larger. Under-ice turbulence was much smaller than that recorded in the oceans and in coastal regions with tide. These results provide better knowledge of under-ice turbulence and heat-flux variations and are useful for the future development of a Baltic Sea ice salinity model.