Novoselova E.V., Belonenko T.V.

The Lofoten Basin in the Norwegian Sea is a real reservoir of the Atlantic waters. The shape of the Basin in the form of a bowl and a great depth with its monotonous increase to the center results in the Atlantic water gradually deepen and fill the Basin. The deepening of the Atlantic waters in the Lofoten Basin determines not only the structure of its waters but also the features of the ocean-atmosphere interaction. Flowing through the transit regions, the Atlantic waters lose heat to the atmosphere, mix with the surrounding water masses and undergo a transformation, which causes the formation of deep ocean waters. At the same time, the heat input with the Atlantic waters significantly exceeds its loss to the atmosphere in the Lofoten Basin.
We study isopycnal advection and diapycnal mixing in the Lofoten Basin. We use the GLORYS12V1 oceanic reanalysis data and analyze four isosteric δ-surfaces. We also calculate the depth of their location. We establish that δ-surfaces have the slope eastward with maximal deepening where the quasi-permanent Lofoten Vortex is located. We analyze the temperature distribution on the isosteric δ-surfaces as well as the interannual and seasonal variability of their location depth.
The maximal depth on the isosteric surfaces is observed in 2010, which is known as the year of the largest mixed layer depths in the Lofoten Basin according to the ARGO buoys. We demonstrate the same correspondence to in 2000, 2010, 2013.
The maximal depth on the isosteric surfaces is observed is reached in summer. The maximal areas with the greatest depths also are observed in summer in contrast to a minimum in winter. This means a certain inertia of changes in the thermohaline characteristics of Atlantic Waters as well as a shift of 1–2 seasons of the influence of deep convection on isosteric surfaces.
It is shown that isopycnic advection in the Lofoten Basin makes a significant contribution to its importance as the main thermal reservoir of the Nordic Seas.

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