Climatic Structure and Intra-Annual Variability of Temperature Fronts on the Ocean Surface in the Patagonian Shelf Region

Yu. V. Artamonov✉, E. A. Skripaleva, N. V. Nikolsky

Marine Hydrophysical Institute of RAS, Sevastopol, Russian Federation

✉ e-mail: artam-ant@yandex.ru

Abstract

Purpose. The aim of the study is to analyze the features of mean long-term structure and intra-annual variability of the characteristics of temperature fronts on the ocean surface in the Patagonian shelf region.

Methods and Results. Mean daily values of the ocean surface temperature from the NOAA OI SST data and the geostrophic velocity components on the surface at the nodes of a 0.25° regular grid from the CMEMS reanalysis for 1993–2020 were used. It is shown that at the western periphery of a large-scale cyclonic meander formed by the currents in the Patagonian shelf region (south of 45°S), three branches of the Subantarctic Front are traced; they correspond to the West Falkland Current and to two jets of the East Falkland Current. North of 45°S, where one Falkland Current jet is observed, one branch of the Subantarctic Front is identified. On the eastern periphery of the meander, the front corresponding to the common stream of the Brazil Current and the Falkland Return Current is revealed. Besides, south of 40°S, a separate branch of the Subantarctic Front corresponding to one more recirculation of the Falkland Current is observed. It is shown that at the meander western periphery, the branches of the Subantarctic Front are most intensified in February – March, at its eastern periphery – in March – April, and at the meander northern peak (in the zone of the Brazil – Falkland Confluence) – in April – May and November.

Conclusions. It is found that on the western periphery of the cyclonic meander, south of 45°S, the main branch of the Subantarctic Front approximately follows the 900–1000 m isobaths, north of 45°S – the 150–170 m isobaths, and closer to the Brazil – Falkland Confluence – the 50–60 m isobaths. At the meander eastern periphery, north of 40°S, the main branch of the front is very close to the 800–1000 m isobaths, south of 40°S – to the 1000–2500 m isobaths. It has been established that the differences between the seasonal cycles of intensity of the Subantarctic Front branches are related to the dissimilar warming and cooling rates of surface waters separated by these branches.

Keywords

Patagonian shelf, large-scale cyclonic meander, bottom topography, Subantarctic Front, Falkland Current, Brazil Current, seasonal variability, horizontal temperature gradient

Acknowledgements

The study was carried out within the framework of a theme of state assignment of FSBSI FRC MHI FNNN-2024-0014 “Fundamental studies of interaction processes in the sea – air system which form variability of marine environment physical state at different spatial and temporal scales”.

Original russian text

Original Russian Text © Yu. V. Artamonov, E. A. Skripaleva, N. V. Nikolsky, 2024, published in MORSKOY GIDROFIZICHESKIY ZHURNAL, Vol. 40, Iss. 4, pp. 514–533 (2024)

For citation

Artamonov, Yu.V., Skripaleva, E.A. and Nikolsky, N.V., 2024. Climatic Structure and Intra-Annual Variability of Temperature Fronts on the Ocean Surface in the Patagonian Shelf Region. Physical Oceanography, 31(4), pp. 467-485.

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