In the master thesis we deal with marine turbulence. In the theoretical part, we derive the rate of change of the mean and turbulent kinetic energy using the Reynolds decomposition of Navier-Stokes equation. The turbulent kinetic energy can be qualitatively represented by its viscous dissipation $\varepsilon$, so we seek the best estimate for the latter. Assuming an isotropic and frozen turbulence, we describe the spectra of the velocity fluctuation and the shear fluctuation and introduce the Nasmyth spectrum. Under the same assumptions, we also describe the spectra of temperature fluctuation and temperature fluctuation gradient and introduce the Batchelor spectrum. Both the Nasmyth and Batchelor spectra depend on $\varepsilon$, so we try to find the best method to assign the data to these spectra. All methods tested were adapted to handle only the data in the range of reliable wavenumbers from the sensors of Sea\&Sun's $\texttt{MSS90}$ probe, but can be adapted to any other probe. We test our methods using Monte Carlo simulations and conclude that the best method for fitting data to the Nasmyth spectrum is maximum likelyhood estimation. Meanwhile, all the methods for fitting data to the Batchelor spectrum are useless if $\varepsilon > 10^{-8}~\rm{W/kg}$ due to too long response time of the temperature sensor. Comparison of the results with real data from $\texttt{MSS90}$ shows good agreement between $\varepsilon$ from the best fit to Nasmyth spectrum and $\varepsilon$ from the probe software. On the other hand, $\varepsilon$ from the Batchelor spectrum is typically somewhat smaller than $\varepsilon$ from the Nasmyth spectrum when $\varepsilon < 10^{-8}~\rm{W/kg}$ and completely disagrees with $\varepsilon$ from the Nasmyth spectrum when $\varepsilon > 10^{-8}~\rm{W/kg}$, as expected from Monte Carlo simulations. Finally, we interpret the results of $\varepsilon$-measurements along the Basin II of Port of Koper, obtained in 2008 and 2009 during three 25-hour field campaigns, using meteorological (air temperature, wind speed), hydrological (tides, water level of the Rižana river), oceanographic conditions (temperature, salinity and density distribution in the basin, vertical shear of the currents near the basin) and also ship maneuvers during the measurements.
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