Observation, Parameterization and Simulation of Turbulent Mixing in the Gulf of Finland, the Baltic Sea

Abstract-Three time series of shear microstructure measurements (duration 13, 24 and 14 h respectively) were performed in 3 different wind forcing regimes as well as in 3 different background density stratification and current velocity shear situations at the entrance to the Gulf of Finland, in July 1998. Vertical shear of current velocity was enhanced by near-inertial waves during the first (A1) and third (A3) time series. We compared a Richardson number based parameterization and an estimation using the two equation k-e turbulence closure (General Ocean Turbulence Model, GOTM) with ¿measured¿ eddy diffusivities. For two out of the three time series eddy diffusivities calculated via a Richardson number parameterization and via simulation using the k-e model agreed well with the experimental data. However, in the case of relatively high current velocity shear and weak background density stratification (time series A3) both applied methods resulted in a remarkable discrepancy against the measured eddy diffusivity. On the contrary, calculations with a new parameterization scheme, which considers the internal wave kinetic energy fitted well for all three time series. Similarly the modified k-e simulations which considered the internal wave energy level better matched the measured profiles.

LILOVER Madis-Jaak;  STIPS Adolf; 

2008-07-03

IEEE

JRC44691

http://www.us-eu-baltic2008.org/UserFiles/File/program.pdf,    http://www.us-eu-baltic2008.org/index.cfm,    https://publications.jrc.ec.europa.eu/repository/handle/JRC44691,