Structure of intrusions and fronts in the deep layer of the Eurasian basin and Makarov basin (Arctic)

Numerous CTD data obtained in the Eurasian and Makarov basins in the Arctic during the Polarstern (1996), Oden, and Louis S. St. Laurent (1994) international polar expeditions are analysed to describe fronts and intrusions observed in the deep layer (600–1300 m). The hydrological parameters were estimated from available CTD data, which made it possible to identify different types of fronts (baroclinic, thermohaline, and compound types of fronts) and analyze intrusive layering taking into account the peculiarities of the thermohaline structure of fronts. The field data are interpreted using an interleaving model describing the formation of intrusions on the baroclinic and pure thermohaline fronts under conditions of absolutely stable stratification. It is assumed that differential mixing is the main instability mechanism. Estimates of the vertical and lateral diffusivities in the frontal zones of the deep Arctic layer are presented.