Impact of the Arctic Ocean Atlantic water layer on Siberian shelf hydrography.

Dmitrenko, Igor A., Kirillov, Sergey A., Tremblay, L. Bruno, Bauch, Dorothea, Hölemann, Jens A. , Krumpen, Thomas, Kassens, Heidemarie, Wegner, Carolyn, Heinemann, Günther and Schröder, David (2010) Impact of the Arctic Ocean Atlantic water layer on Siberian shelf hydrography. Open Access Journal of Geophysical Research: Oceans, 115 (C8). C08010. DOI 10.1029/2009JC006020.

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Abstract

This paper examines the role of the Arctic Ocean Atlantic water (AW) in modifying
the Laptev Sea shelf bottom hydrography on the basis of historical records from 1932 to
2008, field observations carried out in April–May 2008, and 2002–2009 cross‐slope
measurements. A climatology of bottom hydrography demonstrates warming that extends
offshore from the 30–50 m depth contour. Bottom layer temperature‐time series
constructed from historical records links the Laptev Sea outer shelf to the AW boundary
current transporting warm and saline water from the North Atlantic. The AW warming of
the mid‐1990s and the mid‐2000s is consistent with outer shelf bottom temperature
variability. For April–May 2008 we observed on‐shelf near‐bottom warm and saline water
intrusions up to the 20 m isobath. These intrusions are typically about 0.2°C warmer and
1–1.5 practical salinity units saltier than ambient water. The 2002–2009 cross‐slope
observations are suggestive for the continental slope upward heat flux from the AW to the
overlying low‐halocline water (LHW). The lateral on‐shelf wind‐driven transport of the
LHW then results in the bottom layer thermohaline anomalies recorded over the Laptev
Sea shelf. We also found that polynya‐induced vertical mixing may act as a drainage of
the bottom layer, permitting a relatively small portion of the AW heat to be directly
released to the atmosphere. Finally, we see no significant warming (up until now) over the
Laptev Sea shelf deeper than 10–15 m in the historical record. Future climate change,
however, may bring more intrusions of Atlantic‐modified waters with potentially warmer
temperature onto the shelf, which could have a critical impact on the stability of offshore
submarine permafrost.

Document Type: Article
Additional Information: WOS:000280720000004
Keywords: Hydrology; Siberian shelf; Atlantic Water; Bottom water layer; Laptev Sea; Boundary current; Variability; Intermediate; Permafrost; Slope; Ice
Research affiliation: AWI
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1029/2009JC006020
ISSN: 2169-9275
Projects: Polynya, Laptev Sea System
Expeditions/Models/Experiments:
Date Deposited: 26 Aug 2010 08:25
Last Modified: 27 Feb 2018 10:04
URI: http://oceanrep.geomar.de/id/eprint/8816

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