Investigation of applicability of different approaches to calculation of geostrophic currents on the example of under-ice eddies forming ice rings on Lake Baikal

Abstract

This work is devoted to the study of the spatial distribution of horizontal currents in subglacial anticyclonic eddies leading to the formation of ring structures on the spring ice of Lake Baikal. The horizontal fields of geostrophic currents were calculated using the dynamic method, with the main attention paid to the comparison of different approaches to the calculation of water density, including the TEOS-10 software package specially adapted for Baikal conditions. Measured water temperature and conductivity in the area of the ring structure in 2009 were used as input data. And as reference data - series of profiles of velocity and direction of currents in a similar vortex in 2020, measured for the first time. Comparisons showed that the use of outdated methods (such as the Krotova method or the Chen-Millero equation) leads to significant discrepancies with real measurements, while the adapted TEOS-10 package demonstrates the best agreement. In general, the dynamic approach proved to be valid and can be successfully applied to study the flow fields in Lake Baikal. In the course of the conducted studies, a number of characteristic features of the current structure in the investigated subglacial circulations were revealed and described for the first time.