Water, heat and salt balance of the south-eastern part of the Barents Sea

The south-eastern part of the Barents Sea is located away from the main currents, with a combination of climatic, hydrological and oceanological processes creating conditions that make the region different from the rest of the Barents Sea such that it is seen as a separate region and called sometimes the Pechora Sea. Despite the intensive economic activity in the south-eastern part of the Barents Sea, it is not yet clear to what extent the general Atlantic water transport in the Barents Sea and, consequently, the transport of heat and salt, affects this region. Therefore, the aim of this study was to assess advective flows at open boundaries, as well as other components of the water, heat and salt balances of the south-eastern part of the Barents Sea. Based on monthly average data from the MERCATOR GLORYS12V1 reanalysis for the period 1993–2018, we calculated water transport, heat and salt flows at the boundaries of the south-eastern part of the Barents Sea (at 50° E in the west, at 71° N in the north and in the Kara Gate Strait); to close the balances, an assessment was made of sea-atmosphere interaction characteristics on the sea surface based on ECMWF ERA5 reanalysis data. Water, heat and salt balances were combined with a residual not exceeding 1.6 %. Linear trends for the characteristics obtained were calculated. It is revealed that the average long-term resulting water transport in the south-eastern part of the Barents Sea is directed from the north-west of the region to the Kara Gate Strait (0.40 Sv). This current is associated with the Atlantic waters and also carries heat and salt. The resulting heat input (5.92 TW) creates a heat excess in the water area, which is compensated for by interaction with the atmosphere (1.86 TW). The salt flow through the region is estimated at 13.98 t/s. During the study period, all the main flows have a statistically significant positive trend in the incoming and outgoing parts of the balances: water transport — 0.005 Sv per year; salt flow — 0.18 t/s per year. This indicates an increase in the transit of Atlantic waters through the south-eastern part of the Barents Sea. An increase in the advective heat flux (0.15 TW per year) across the western border is accompanied by an increase in its release into the atmosphere (0.07 TW per year) and an increase in evaporation of 6.9 mm per year. Sea levels are also rising at a rate of 0.27 cm per year. Thus, the increasing dynamics of the processes in the region is a factor to take into account in conducting economic activities.

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