Pavlov Vladimir

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  • Article
    The Atlantic Water boundary current in the Nansen Basin : transport and mechanisms of lateral exchange
    (John Wiley & Sons, 2016-09-22) Våge, Kjetil ; Pickart, Robert S. ; Pavlov, Vladimir ; Lin, Peigen ; Torres, Daniel J. ; Ingvaldsen, Randi B. ; Sundfjord, Arild ; Proshutinsky, Andrey
    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.
  • Article
    The Atlantic Water boundary current north of Svalbard in late summer
    (John Wiley & Sons, 2017-03-21) Perez-Hernandez, M. Dolores ; Pickart, Robert S. ; Pavlov, Vladimir ; Våge, Kjetil ; Ingvaldsen, Randi B. ; Sundfjord, Arild ; Renner, Angelika H. H. ; Torres, Daniel J. ; Erofeeva, Svetlana Y.
    Data from a shipboard hydrographic/velocity survey carried out in September 2013 of the region north of Svalbard in the Nansen Basin are analyzed to characterize the Atlantic Water (AW) boundary current as it flows eastward along the continental slope. Eight meridional transects across the current, spanning an alongstream distance of 180 km, allow for a detailed description of the current and the regional water masses. During the survey the winds were light and there was no pack-ice. The mean section reveals that the boundary current was O(40 km) wide, surface-intensified, with a maximum velocity of 20 cm/s. Its mean transport during the survey was 3.11 ± 0.33 Sv, of which 2.31 ± 0.29 Sv was AW. This suggests that the two branches of AW entering the Arctic Ocean via Fram Strait—the Yermak Plateau branch and the Svalbard branch—have largely combined into a single current by 30°E. At this location the boundary current meanders with a systematic change in its kinematic structure during offshore excursions. A potential vorticity analysis indicates that the flow is baroclinically unstable, consistent with previous observations of AW anticyclones offshore of the current as well as the presence of a near-field cyclone in this data set. Our survey indicates that only a small portion of the boundary current is diverted into the Kvitøya Trough (0.17 ± 0.08 Sv) and that the AW temperature/salinity signal is quickly eroded within the trough.
  • Article
    Structure, transport, and seasonality of the Atlantic Water boundary current north of Svalbard: Results from a yearlong mooring array
    (American Geophysical Union, 2019-02-15) Pérez-Hernández, M. Dolores ; Pickart, Robert S. ; Torres, Daniel J. ; Bahr, Frank B. ; Sundfjord, Arild ; Ingvaldsen, Randi B. ; Renner, Angelika H. H. ; Beszczynska-Möller, Agnieszka ; von Appen, Wilken‐Jon ; Pavlov, Vladimir
    The characteristics and seasonality of the Svalbard branch of the Atlantic Water (AW) boundary current in the Eurasian Basin are investigated using data from a six‐mooring array deployed near 30°E between September 2012 and September 2013. The instrument coverage extended to 1,200‐m depth and approximately 50 km offshore of the shelf break, which laterally bracketed the flow. Averaged over the year, the transport of the current over this depth range was 3.96 ± 0.32 Sv (1 Sv = 106 m3/s). The transport within the AW layer was 2.08 ± 0.24 Sv. The current was typically subsurface intensified, and its dominant variability was associated with pulsing rather than meandering. From late summer to early winter the AW was warmest and saltiest, and its eastward transport was strongest (2.44 ± 0.12 Sv), while from midspring to midsummer the AW was coldest and freshest and its transport was weakest (1.10 ± 0.06 Sv). Deep mixed layers developed through the winter, extending to 400‐ to 500‐m depth in early spring until the pack ice encroached the area from the north shutting off the air‐sea buoyancy forcing. This vertical mixing modified a significant portion of the AW layer, suggesting that, as the ice cover continues to decrease in the southern Eurasian Basin, the AW will be more extensively transformed via local ventilation.