The Atlantic Water boundary current in the Nansen Basin: Transport and mechanisms of lateral exchange

Abstract

Data from a shipboard hydrographic survey near 30°E in the Nansen Basin of the Arctic Ocean are used to investigate the structure and transport of the Atlantic Water boundary current. Two high‐resolution synoptic crossings of the current indicate that it is roughly 30 km wide and weakly middepth‐intensified. Using a previously determined definition of Atlantic Water, the transport of this water mass is calculated to be 1.6 ± 0.3 Sv, which is similar to the transport of Atlantic Water in the inner branch of the West Spitsbergen Current. At the time of the survey a small anticyclonic eddy of Atlantic Water was situated just offshore of the boundary current. The data suggest that the feature was recently detached from the boundary current, and, due to compensating effects of temperature and salinity on the thermal wind shear, the maximum swirl speed was situated below the hydrographic property core. Two other similar features were detected within our study domain, suggesting that these eddies are common and represent an effective means of fluxing warm and salty water from the boundary current into the interior. An atmospheric low‐pressure system transiting south of our study area resulted in southeasterly winds prior to and during the field measurements. A comparison to hydrographic data from the Pacific Water boundary current in the Canada Basin under similar atmospheric forcing suggests that upwelling was taking place during the survey. This provides a second mechanism related to cross‐stream exchange of heat and salt in this region of the Nansen Basin.

Hydrography, transport and mixing of the West Spitsbergen Current: the Svalbard Branch in summer 2015

“…A subsurface salinity maximum between 100 m and 400 m depth was found in all three sections, similar to previous studies in this region (Cokelet et al, 2008;Våge et al, 2016;Meyer et al, 2016). Compared to the climatology, the salinities were higher in all sections.…”

“…• E) (Våge et al, 2016). When compared with the Monthly Isopycnal and Mixed-layer Ocean Climatology (MIMOC) (Schmidtko et al, 2013) in August (not shown), AW temperatures in 2015 were up to 1.8…”

“…• E (Perkin and Lewis, 1984;Cokelet et al, 2008;Våge et al, 2016;Meyer et al, 2016). Acoustically-tracked subsurface floats revealed a shortcut across the YP (Gascard et al, 1995), through a topographic passage at 80 (Padman and Dillon, 1991;Perkin and Lewis, 1984).…”

Short commentary on marine productivity at Arctic shelf breaks: upwelling, advection and vertical mixing

“…There it has appeared both in numerous personal communications among the community working with the physical and ecological environment of the Barents Sea and a number of published articles (see e.g. Falk-Petersen et al, 2014;Tetzlaff et al, 2014;Wassmann et al, 2015;Hunt et al, 2016;Våge et al, 2016;Haug et al, 2017). Thus it might appear as if shelf break upwelling is currently being cemented as a universal paradigm to conceptualize the "new" Arctic Ocean where global climate change is taking us.…”

Short Commentary on Marine Productivity at Arctic Shelf Breaks: Upwelling, Advection and Vertical Mixing

“…There it has appeared both in numerous personal communications among the community working with the physical and ecological environment of the Barents Sea, as well as a number of published articles (see e.g. -Petersen et al, 2014;Tetzlaff et al, 2014;Wassmann et al, 2015;Hunt et al, 2016;Våge et al, 2016;Haug et al, 2017).…”