The dynamics of a saltwater marine lake (Big Lake, Island of Mljet, Adriatic Sea) as revealed by temperature measurements

Abstract

         This paper describes hydrographic and dynamic conditions in the Mljet lakes, through the analysis of high-frequency temperature measurements carried out at an intermediate layer of Big Lake (BL) and Soline Channel during two years (December 2005-October 2007). It appears that the lakes may be colder than the open sea during wintertime by as much as 2-3°C and warmer at the surface during summer by as much as 4°C. Several interesting processes were captured within the series of which we investigated the wintertime cooling that occurred in 2006, diurnal and semidiurnal temperature changes driven by the tides within the connecting channel and the occurrence of turbulence in BL close to the connecting channel. The latter seems to have large implications for the thermocline/pycnocline deepening during the summertime, as incoming open ocean waters are much denser than the BL waters.