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Circulation in the northwest L aptev S ea in the eastern A rctic O cean: Crossroads between S iberian R iver water, A tlantic water and polynya‐formed dense water
Author(s) -
Janout Markus A.,
Hölemann Jens,
Timokhov Leonid,
Gutjahr Oliver,
Heinemann Günther
Publication year - 2017
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2017jc013159
Subject(s) - oceanography , geology , halocline , hydrography , arctic , boundary current , trough (economics) , current (fluid) , north atlantic deep water , canada basin , thermohaline circulation , water column , arctic dipole anomaly , ocean current , stratification (seeds) , arctic ice pack , salinity , drift ice , economics , macroeconomics , seed dormancy , botany , germination , dormancy , biology
This paper investigates new observations from the poorly understood region between the Kara and Laptev Seas in the Eastern Arctic Ocean. We discuss relevant circulation features including riverine freshwater, Atlantic‐derived water, and polynya‐formed dense water, emphasize Vilkitsky Strait (VS) as an important Kara Sea gateway, and analyze the role of the adjacent ∼250 km‐long submarine Vilkitsky Trough (VT) for the Arctic boundary current. Expeditions in 2013 and 2014 operated closely spaced hydrographic transects and 1 year‐long oceanographic mooring near VT's southern slope, and found persistent annually averaged flow of 0.2 m s −1 toward the Nansen Basin. The flow is nearly barotropic from winter through early summer and becomes surface intensified with maximum velocities of 0.35 m s −1 from August to October. Thermal wind shear is maximal above the southern flank at ∼30 m depth, in agreement with basinward flow above VT's southern slope. The subsurface features a steep front separating warm (–0.5°C) Atlantic‐derived waters in central VT from cold (<–1.5°C) shelf waters, which episodically migrates across the trough indicated by current reversals and temperature fluctuations. Shelf‐transformed waters dominate above VT's slope, measuring near‐freezing temperatures throughout the water column at salinities of 34–35. These dense waters are vigorously advected toward the Eurasian Basin and characterize VT as a conduit for near‐freezing waters that could potentially supply the Arctic Ocean's lower halocline, cool Atlantic water, and ventilate the deeper Arctic Ocean. Our observations from the northwest Laptev Sea highlight a topographically complex region with swift currents, several water masses, narrow fronts, polynyas, and topographically channeled storms.