Simple analytic models developed in this study are applied to long-term averages of reanalysis surface salinity data to quantify two fundamental properties of ocean currents. The first model is based on the new Freshening Length schema and its application to the Irminger Current yields a ratio of about 5 between the turbulent entrainment rates of surrounding fresher surface waters west and east of Greenland. The second model is based on the steady solution of the advection-diffusion equation subject to suitable boundary conditions. The application of this model to the spreading of fresh, snow-melt, water from the delta of the Po river in the northwest Adriatic Sea into the rest of the Sea yields a ratio of $8 \times 10^4$ m between the eddy exchange coefficient and the speed of advection in the Sea