Effect of Diapycnal Mixing on Climatic Characteristics of the Laptev Sea in the Ice-Free Period

B. A. Kagan1, E. V. Sofina1, 2, ✉

1 Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russian Federation

2 Russian State Hydrometeorological University, Saint-Petersburg, Russian Federation

✉ e-mail: sofjina_k@mail.ru

Abstract

Purpose. The present study is aimed at evaluating the role of diapycnal mixing conditioned by the dissipation of baroclinic tide energy, in formation of climatic characteristics of the Laptev Sea in summer period.

Methods and Results. The sea dynamics with and without tidal forcing is reproduced using the high-resolution 3D finite element model. Spatial resolution of the unstructured grid varied from 1 to 18 km. The wind and thermohaline (seawater temperature and salinity restoring to the specified values on the sea surface) forcings, as well as the sea level at the domain open boundary, are set by the climatic affects corresponding to the summer (July, August) ice-free period in the Laptev Sea. The tidal forcing is set by an indirect method: the diapycnal diffusion coefficient defined, in accordance with the approximation of “weak interaction” of turbulence of various origins, by solving the problem on the baroclinic tide dynamics, is added to the vertical turbulent diffusion coefficient controlled by the wind and thermohaline forcings.

Conclusions. The changes in seawater temperature and salinity induced by diapycnal mixing, having been compared to the climatic characteristics as such show that, as a rule, they (especially, their extremal values) are well-detectable, and that their ignoring is not always acceptable. This is confirmed by the average (over the tidal cycle and over the area of the identified sea zone differing from the others by depth) vertical profiles of the uncorrected and corrected (due to the internal tidal wave effects) vertical turbulent mixing coefficients. The profiles differ from one another, if not in the entire sea, then at least within ~ 40% of its volume.

Keywords

internal waves, tide, climatic characteristics, turbulent mixing, the Laptev Sea

Acknowledgements

The work was carried out within the framework of the state assignment of Shirshov Institute of Oceanology, Russian Academy of Sciences, on theme No. FMWE-2021-0014.

Original russian text

Original Russian Text © B. A. Kagan, E. V. Sofina, 2022, published in MORSKOY GIDROFIZICHESKIY ZHURNAL, Vol. 38, Iss. 2, pp. 218-234 (2022)

For citation

Kagan, B.A. and Sofina, E.V., 2022. Effect of Diapycnal Mixing on Climatic Characteristics of the Laptev Sea in the Ice-Free Period. Physical Oceanography, 29(2), pp. 204-219. doi:10.22449/1573-160X-2022-2-204-219

DOI

10.22449/1573-160X-2022-2-204-219

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