Seasonality of Submesoscale Coherent Vortices in the Northern Baltic Proper: A Model Study
https://doi.org/10.7868/S2073667321030114
Abstract
A very high-resolution modelling of the northern Baltic Proper shows that in summer the cyclonic and anticyclonic submesoscale coherent vortices (SCVs) with the extremum of vertical vorticity in the surface layer are formed, while the subsurface anticyclonic SCVs in the shape of convex lenses in the density field prevail over the cyclonic SCVs – concave lenses, with the vertical vorticity extremum in the cold intermediate layer below the seasonal thermocline and above the permanent halocline. In winter the seasonal thermocline and cold intermediate layer are replaced by a relatively deep convectively-mixed layer which makes the formation of subsurface concave cyclonic and convex anticyclonic lenses impossible there. Instead, the winter-time cyclonic SCVs with the vertical vorticity extremum at the surface dominate. The core of winter-time cyclonic SCVs is characterized by a negative temperature anomaly throughout the mixed layer. During its life cycle lasting up to several months and more, the modelled SCVs can repeatedly merge with other SCVs of the same sign of vorticity, and the merger makes the eddy stronger thereby contributing to its longevity.
Keywords
Baltic Sea,
very high-resolution numerical modelling,
submesoscale coherent vortex,
gravitational convection in rotating fluid
Supporting agencies: The allocation of computing time on High Performance Computing cluster by the Tallinn University of Technology and by the University of Tartu is gratefully acknowledged. GETM community in Leibniz Institute of Baltic Sea Research (IOW) is acknowledged for their technical support and the maintenance of model code. Germo Väli was supported by the Estonian Research Council (grant no. PRG602 and grant no. IUT19-6). Victor Zhurbas was supported by the budgetary financing of the Shirshov Institute of Oceanology RAS (Project No. 0128-2021-0001).
About the Authors
G. Väli
Tallinn University of Technology, Department of Marine Systems
Estonia
Estonia
12618, Akadeemia tee, 15A, Tallinn
V. M. Zhurbas
Shirshov Institute of Oceanology, RAS
Russian Federation
Russian Federation
117997, Nahimovsky Pr., 36, Moscow
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Review
For citations:
Väli G., Zhurbas V.M. Seasonality of Submesoscale Coherent Vortices in the Northern Baltic Proper: A Model Study. Fundamental and Applied Hydrophysics. 2021;14(3):122-129. https://doi.org/10.7868/S2073667321030114
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