scholarly journals Picophytoplankton distribution along Khatanga Bay-shelf-continental slope environment gradients in the western Laptev Sea

Heliyon ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. e06224
Author(s):  
Tatiana A. Belevich ◽  
Аndrey B. Demidov ◽  
Peter N. Makkaveev ◽  
Sergei A. Shchuka ◽  
Mikhail V. Flint
Oceanology ◽  
2019 ◽  
Vol 59 (5) ◽  
pp. 648-657
Author(s):  
I. N. Sukhanova ◽  
M. V. Flint ◽  
A. V. Fedorov ◽  
E. G. Sakharova ◽  
V. A. Artemyev ◽  
...  
Keyword(s):  

2018 ◽  
Author(s):  
Andrey Pnyushkov ◽  
Igor V. Polyakov ◽  
Laurie Padman ◽  
An T. Nguyen

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.


2019 ◽  
Vol 59 (5) ◽  
pp. 755-770
Author(s):  
A. B. Demidov ◽  
V. I. Gagarin ◽  
E. G. Arashkevich ◽  
P. N. Makkaveev ◽  
I. V. Konyukhov ◽  
...  

Spatial distribution of phytoplankton primary production and chlorophyll was studied based on the data of three cruises carried out in AugustSeptember of 2015, 2017 and 2018. The average value of water column primary production (IPP) along the transect from Lena`s mouth to the continental slope was 2.8 fold higher than that one along the transect from Khatanga`s mouth, which was explained by the level of incident radiation and nutrients concentration. Along the cross-slope transects increasing of photosynthetically layer integrated chlorophyll (Chlph) occurred due to developing of deep maxima. IPP and Chlph increasing was registered in the vicinity of the continental slope. In AugustSeptember the averaged IPP value was 100 mgC m-2 d-1 that is the evidence of oligotrophy of the Laptev Sea at the end of summer and at the beginning of autumn.


Ocean Science ◽  
2014 ◽  
Vol 10 (1) ◽  
pp. 141-154 ◽  
Author(s):  
D. Bauch ◽  
S. Torres-Valdes ◽  
I. Polyakov ◽  
A. Novikhin ◽  
I. Dmitrenko ◽  
...  

Abstract. A general pattern in water mass distribution and potential shelf–basin exchange is revealed at the Laptev Sea continental slope based on hydrochemical and stable oxygen isotope data from the summers 2005–2009. Despite considerable interannual variations, a frontal system can be inferred between shelf, continental slope and central Eurasian Basin waters in the upper 100 m of the water column along the continental slope. Net sea-ice melt is consistently found at the continental slope. However, the sea-ice meltwater signal is independent from the local retreat of the ice cover and appears to be advected from upwind locations. In addition to the along-slope frontal system at the continental shelf break, a strong gradient is identified on the Laptev Sea shelf between 122° E and 126° E with an eastward increase of riverine and sea-ice related brine water contents. These waters cross the shelf break at ~ 140° E and feed the low-salinity halocline water (LSHW, salinity S < 33) in the upper 50 m of the water column. High silicate concentrations in Laptev Sea bottom waters may lead to speculation about a link to the local silicate maximum found within the salinity range of ~ 33 to 34.5, typical for the Lower Halocline Water (LHW) at the continental slope. However brine signatures and nutrient ratios from the central Laptev Sea differ from those observed at the continental slope. Thus a significant contribution of Laptev Sea bottom waters to the LHW at the continental slope can be excluded. The silicate maximum within the LHW at the continental slope may be formed locally or at the outer Laptev Sea shelf. Similar to the advection of the sea-ice melt signal along the Laptev Sea continental slope, the nutrient signal at 50–70 m water depth within the LHW might also be fed by advection parallel to the slope. Thus, our analyses suggest that advective processes from upstream locations play a significant role in the halocline formation in the northern Laptev Sea.


2012 ◽  
Vol 42 (1) ◽  
pp. 78-94 ◽  
Author(s):  
A. V. Pnyushkov ◽  
I. V. Polyakov

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.


arktos ◽  
2018 ◽  
Vol 4 (1) ◽  
Author(s):  
Elizaveta Logvina ◽  
Alexeу Krylov ◽  
Еkaterina Taldenkova ◽  
Valentina Blinova ◽  
Vladimir Sapega ◽  
...  

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