Observations of Tidally Induced Currents over the Continental Slope of the Laptev Sea, Arctic Ocean

Abstract Two year-long (2004–05 and 2005–06) records of currents from two moorings deployed at the continental slope of the Laptev Sea (78°26′N, 125°40′E) are used in order to define the properties of tidal currents in the upper ~200-m ocean layer. Harmonic and spectral analyses of currents showed that the semidiurnal tidal constituent S2 dominates over the semidiurnal M2 and diurnal constituents. This dominance of the S2 constituent in the tidal currents is due to resonant interaction of the superinertial wave with sloping bottom topography. In contrast to the tidal currents, sea level changes are dominated by the M2 constituent, as seen from a tidal model by L. Padman and S. Erofeeva, using assimilation of observational data. Strong anticorrelation (−0.73 ± 0.05) was found between the upper 50-m S2 current amplitudes and local sea ice concentration, with fourfold (from ~2.0 to 8.5 cm s−1) amplification of tidal currents under ice-free conditions. This is probably due to a change of local resonance conditions for the S2 tidal current. These findings may be important for understanding the increasing role of tides in a seasonally ice-free Arctic Ocean.

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Structure and dynamics of mesoscale eddies over the Laptev Sea continental slope in the Arctic Ocean

10.5194/os-2018-22 ◽

2018 ◽

Cited By ~ 1

Author(s):

Andrey Pnyushkov ◽

Igor V. Polyakov ◽

Laurie Padman ◽

An T. Nguyen

Keyword(s):

Arctic Ocean ◽

Continental Slope ◽

Mesoscale Eddies ◽

The Arctic ◽

Laptev Sea ◽

Surface Mixed Layer ◽

Fram Strait ◽

Structure And Dynamics ◽

The Arctic Ocean ◽

The Laptev Sea

Abstract. Heat fluxes steered by mesoscale eddies may be a significant (but still not quantified) source of heat to the surface mixed layer and sea ice cover in the Arctic Ocean, as well as a source of nutrients for enhancing seasonal productivity in the near-surface layers. Here we use four years (2007–2011) of velocity and hydrography records from a moored profiler over the Laptev Sea slope, and 15 months (2008–2009) of acoustic Doppler current profiler data from a nearby mooring, to investigate the structure and dynamics of eddies at the continental margin of the eastern Eurasian Basin. Typical eddy scales are radii of order of 10 km, heights of six hundred meters, and maximum velocities of ~ 0.1 m s −1. Eddies are approximately equally divided between cyclonic and anticyclonic polarizations, contrary to prior observations from the deep basins and along the Lomonosov Ridge. Eddies are present in the mooring records about 20–25 % of the time, taking about one week to pass through the mooring at an average frequency of about one eddy per month. We found the eddies observed are formed in two distinct regions–near Fram Strait, where the western branch of Atlantic Water (AW) enters the Arctic Ocean, and near Severnaya Zemlya, where the Fram Strait and Barents Sea branches of the AW inflow merge. These eddies, embedded in the Arctic Circumpolar Boundary Current, carry anomalous water properties along the eastern Arctic continental slope. The enhanced diapycnal mixing that we found within EB eddies suggests a potentially important role for eddies in the vertical redistribution of heat in the Arctic Ocean interior.

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Review of Structure and dynamics of mesoscale eddies over the Laptev Sea continental slope in the Arctic Ocean

10.5194/os-2018-22-rc1 ◽

2018 ◽

Author(s):

Anonymous

Keyword(s):

Arctic Ocean ◽

Continental Slope ◽

Mesoscale Eddies ◽

The Arctic ◽

Laptev Sea ◽

Structure And Dynamics ◽

The Arctic Ocean ◽

The Laptev Sea

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Review of “Structure and dynamics of mesoscale eddies over the Laptev Sea continental slope in the Arctic Ocean” by Pnyushkov et al.

10.5194/os-2018-22-rc2 ◽

2018 ◽

Author(s):

Anonymous

Keyword(s):

Arctic Ocean ◽

Continental Slope ◽

Mesoscale Eddies ◽

The Arctic ◽

Laptev Sea ◽

Structure And Dynamics ◽

The Arctic Ocean ◽

The Laptev Sea

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An observational and modelling analysis of Laptev Sea (Arctic Ocean) ice variations during summer

Annals of Glaciology ◽

10.3189/172756401781818699 ◽

2001 ◽

Vol 33 ◽

pp. 533-538 ◽

Cited By ~ 1

Author(s):

K. Görgen ◽

J. Bareiss ◽

A. Helbig ◽

A. Rinke ◽

K. Dethloff

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Large Scale ◽

Climate Model ◽

Regional Climate ◽

Laptev Sea ◽

Simple Relationship ◽

Cyclone Activity ◽

Sea Ice Concentration ◽

The Laptev Sea

AbstractIn this study we investigate the relationship of the atmospheric circulation and the sea-ice distribution in the Laptev Sea, Arctic Ocean, in the summers 1979−96. Sea-ice data from passive-microwave radiometers, global atmospheric data analyses, cyclone statistics and simulations of the regional climate model HIRHAM4 were analyzed to find out if periods of reduced or increased sea-ice concentrations are linked to synoptic patterns (circulation anomalies, cyclone activity). A canonical correlation analysis between Arctic sea-level pressure and sea-ice concentration anomalies confirms large-scale relationships among these variables. We did not find a simple relationship between sea-ice area anomalies and cyclone activity in the Laptev Sea area

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Structure and dynamics of mesoscale eddies over the Laptev Sea continental slope in the Arctic Ocean

Ocean Science ◽

10.5194/os-14-1329-2018 ◽

2018 ◽

Vol 14 (5) ◽

pp. 1329-1347 ◽

Cited By ~ 7

Author(s):

Andrey Pnyushkov ◽

Igor V. Polyakov ◽

Laurie Padman ◽

An T. Nguyen

Keyword(s):

Arctic Ocean ◽

Continental Slope ◽

Mesoscale Eddies ◽

The Arctic ◽

Laptev Sea ◽

Surface Mixed Layer ◽

Fram Strait ◽

Structure And Dynamics ◽

The Arctic Ocean ◽

The Laptev Sea

Abstract. Heat fluxes steered by mesoscale eddies may be a significant, but still not quantified, source of heat to the surface mixed layer and sea ice cover in the Arctic Ocean, as well as a source of nutrients for enhancing seasonal productivity in the near-surface layers. Here we use 4 years (2007–2011) of velocity and hydrography records from a moored profiler over the Laptev Sea slope and 15 months (2008–2009) of acoustic Doppler current profiler data from a nearby mooring to investigate the structure and dynamics of eddies at the continental margin of the eastern Eurasian Basin. Typical eddy scales are radii of the order of 10 km, heights of 600 m, and maximum velocities of ∼0.1 m s−1. Eddies are approximately equally divided between cyclonic and anticyclonic polarizations, contrary to prior observations from the deep basins and along the Lomonosov Ridge. Eddies are present in the mooring records about 20 %–25 % of the time, taking about 1 week to pass through the mooring at an average frequency of about one eddy per month. We found that the eddies observed are formed in two distinct regions – near Fram Strait, where the western branch of Atlantic Water (AW) enters the Arctic Ocean, and near Severnaya Zemlya, where the Fram Strait and Barents Sea branches of the AW inflow merge. These eddies, embedded in the Arctic Circumpolar Boundary Current, carry anomalous water properties along the eastern Arctic continental slope. The enhanced diapycnal mixing that we found within EB eddies suggests a potentially important role for eddies in the vertical redistribution of heat in the Arctic Ocean interior.

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On the biogeochemical signature of the Lena River from its headwaters to the Arctic Ocean

Biogeosciences Discussions ◽

10.5194/bgd-8-2093-2011 ◽

2011 ◽

Vol 8 (2) ◽

pp. 2093-2143 ◽

Cited By ~ 6

Author(s):

I. P. Semiletov ◽

I. I. Pipko ◽

N. E. Shakhova ◽

O. V. Dudarev ◽

S. P. Pugach ◽

...

Keyword(s):

Organic Carbon ◽

Arctic Ocean ◽

River Discharge ◽

Total Carbon ◽

The Arctic ◽

Time Shift ◽

Laptev Sea ◽

Lena River ◽

The Arctic Ocean ◽

The Laptev Sea

Abstract. The Lena River integrates biogeochemical signals from its vast drainage basin and its signal reaches far out over the Arctic Ocean. Transformation of riverine organic carbon into mineral carbon, and mineral carbon into the organic form in the Lena River watershed, can be considered a quasi-equilibrated processes. Increasing the Lena discharge causes opposite effects on total organic (TOC) and inorganic (TCO2) carbon: TOC concentration increases, while TCO2 concentration decreases. Significant inter-annual variability in mean values of TCO2, TOC, and their sum (TC) has been found. This variability is determined by changes in land hydrology which cause differences in the Lena River discharge, because a negative correlation may be found between TC in September and mean discharge in August (a time shift of about one month is required for water to travel from Yakutsk to the Laptev Sea). Total carbon entering the sea with the Lena discharge is estimated to be almost 10 Tg C y−1. The annual Lena River discharge of particulate organic carbon (POC) may be equal to 0.38 Tg (moderate to high estimate). If we instead accept Lisytsin's (1994) statement concerning the precipitation of 85–95% of total particulate matter (PM) (and POC) on the marginal "filter", then only about 0.03–0.04 Tg of POC reaches the Laptev Sea from the Lena River. The Lena's POC export would then be two orders of magnitude less than the annual input of eroded terrestrial carbon onto the shelf of the Laptev and East Siberian seas, which is about 4 Tg. The Lena River is characterized by relatively high concentrations of primary greenhouse gases: CO2 and dissolved CH4. During all seasons the river is supersaturated in CO2 compared to the atmosphere: up to 1.5–2 fold in summer, and 4–5 fold in winter. This results in a narrow zone of significant CO2 supersaturation in the adjacent coastal sea. Spots of dissolved CH4 in the Lena delta channels may reach 100 nM, but the CH4 concentration decreases to 5–20 nM towards the sea, which suggests only a minor role of riverborne export of CH4 for the East Siberian Arctic Shelf (ESAS) CH4 budget in coastal waters. Instead, the seabed appears to be the source that provides most of the CH4 to the Arctic Ocean.

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