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

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 degrees regular grid from the CMEMS reanalysis for 1993-2020 were used. . It is shown that at the western periphery of a largescale cyclonic meander formed by the currents in the Patagonian shelf region (south of 45 degrees 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 degrees 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 degrees 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 degrees S, the main branch of the Subantarctic Front approximately follows the 900-1000 m isobaths, north of 45 degrees 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 degrees S, the main branch of the front is very close to the 800- 1000 m isobaths, south of 40 degrees 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.