Statistic of the Richardson Number According to Observations from the Oceanographic Platform

A. N. Morozov

Marine Hydrophysical Institute of RAS, Sevastopol, Russia

Abstract

The results of measurements carried out on 17 – 21 May 2013 from the oceanographic platform located near Kaciveli coast are discussed. The measurements were performed using a distributed thermoprofiler, an acoustic Doppler current profiler and a CTD probe. Methodical issues of data processing are discussed. The estimation of Richardson numbers (Ri) depended on the resolution of devices is considered. It is shown that the probability of fulfilling the necessary condition for linear instability (P_Ri_ < 0,25) decreases exponentially with increasing increment of depth at which the corresponding derivatives are calculated. P_Ri_ < 0,25 decreases linearly with depth and exhibits a logarithmic dependence on buoyancy frequency. As an alternative to the Richardson numbers, the ratios of the measured average shears of current with shear values estimated from the Garrett and Munk spectra (GM76) are considered.

Keywords

vertical shear of current, Richardson numbers, thermoprofiler, ADCP, the Black Sea

DOI

10.22449/2413-5577-2018-2-39-46

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