Arctic Ocean Model Intercomparison Project: Key outcomes. Boundary condition considerations, readiness of regional models for coupling. Arctic System Model workshop IARC, UAF, Fairbanks, August 6-7, 2007 Andrey Proshutinsky Woods Hole Oceanographic Institution

Regional AOMIP Models

Global AOMIP models AOMIP model IDLANLUWNERSCUCL Home InstituteLos Alamos National Laboratories University of Washington Nansen Environmental and Remote Sensing Center Universite Catholique de Louvain Ocean Model Pedigree POPPOIMMICOMOPA Coupled Sea-Ice Model Yes POP – Parallel Ocean Model; MOM - GFDL Modular Ocean Model POIM – Parallel Ocean Ice Model; MICOM – Miami Isopycnal Ocean Model POM – Princeton Ocean Module Model; OPA – Ocean General Circulation modeling System

Ten AOMIP modeling groups are presented here: AWI - Alfred Wegener Institute - Bremerhaven, Germany; CNF - Frontier Research Center for Global Change, Japan, with International Arctic Research Center, USA GSFC - NASA Goddard Space Flight Center, USA; ICMMG - Institute ofComputational Math. and Math. Geophysics, Russia; IOS -Institute of Ocean Sciences, Canada; LANL -Los Alamos National Laboratory, USA; NPS - Naval Postgraduate School, USA; POL - Proudman Oceanographic Laboratory, Liverpool, UK; UL - Universite Laval, Quebec, Canada; UW - University of Washington, USA.

Arctic Ocean Model Intercomparison Project (AOMIP) Common model domain The AOMIP Grid is defined over a geographic domain that includes the Arctic Ocean, the Bering Strait, the Canadian Arctic Archipelago, the Fram Strait and the Greenland, Iceland, and Norwegian Seas The AOMIP Grid is defined over a geographic domain that includes the Arctic Ocean, the Bering Strait, the Canadian Arctic Archipelago, the Fram Strait and the Greenland, Iceland, and Norwegian Seas.

AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

Model validation The first group of studies has focused on the analysis of differences among model results and between model results and observations.  The first group of studies has focused on the analysis of differences among model results and between model results and observations.  This was important for determining model errors and model uncertainties, and this was the first step in the process of model improvement. GOAL 1

Sealevel Icedrift Hydrography HydrographyIcethickness Iceconcentration Watercirculation Model validation parameters GOAL 1

Model improvement activities Restoring and Flux correction Atmospheric loading Atmospheric loading Vertical and lateral mixing Tidal ocean & ice effects Bering Strait Inflow and river runoff Neptune effect New advection New advection schemes schemes GOAL 1

Investigation of sea level rise: its rate, role of different factors, model errors Atlantic water circulationorigin, variability, sense of rotation Reconstruction of hydrography and circulation based on modeling with dataassimilation Freshwatercontent variability and role of different factors Heat content variability and role of differentfactors Wind- and convection-drivenmixing Process and arctic change studies GOAL 2

Model improvements recommendations:  Tidal forcing is important for Arctic Ocean modeling;  Tidal and inertial dynamics has to be included in the sea ice models as well;  Inverted barometer effect is an important component for simulations of synoptic variability;  Variable river runoff and Bering Strait inflow are important parameters influencing Arctic climate and have to be taken into account;  Land-fast ice is an important regulator of dynamics and thermodynamics because it influences upwelling and downwelling, sea ice production and brine rejection, shelf water properties. GOAL 2

Model improvements Model improvement includes several phases:  - Identification of problems;  - Search for solutions/improvements;  - Testing improvements based on one or two models;  - Recommendations to others; and  - Introduction and testing of new ideas. GOAL 1

Differences for each model between the mean model sea ice concentration and the mean sea ice from GSFC for 1979– The dark line is the concentration contour from the GSFC data. Models from left to right and top to bottom are AWI2, AWI1, UW, NPS, IOS, ICM, LANL, GSFC, and RAS. Scale is from −0.4 (red) to +0.4 (blue) with values nearer zero having less color saturation. Saturated colors indicate larger differences from the observations with red below and blue above the observed. GOAL 1 Sea ice concentration

Sea ice concentration model validation conclusions  Differences among the sea ice concentrations computed by the AOMIP models are greater than differences among four observational data sets.  Regardless of the different model physics and parameters, the results show that the models have more variability than observed, and that, compared to observations, almost all the models underestimate the September sea ice concentration in the central Arctic Ocean.  This underestimation may have important implications for sea ice forecasts. GOAL 1

Sea ice thickness model validation conclusions  There are considerable errors in sea ice thickness in IPCC results. (too simple sea ice rheologies in some of these models. Better models tend to pile up ice in the center of the ocean).  Errors may have important consequences for the atmospheric circulation. Too large ice cover and thickness in the European sector could be significant in ocean-atmosphere interactions and long term variability.  The AOMIP results are dominated by an accumulation of sea ice in the mid-1960s and a return to values before that event in the mid-1960s and a return to values before that event in the last decade of the 20th century. in the last decade of the 20th century.  The IPCC results show a negative trend in Arctic sea ice volume over the 20th century. The AOMIP simulation shows no trend over that period. This suggests that the internal multidecadal variability of the real climate system is underestimated in IPCC models. GOAL 1

Sea ice drift  Gridded observational ice drift fields are used from two products: NSIDC (Fowler, 2003); CERSAT (Ezraty, and Piollé, 2004) GOAL 1 Difference between model CERSAT ice drift speeds (gray shade) and direction (black outline). AWI GSFCIOS NPSUW AWI-2

Sea ice drift model validation results  One class of models has a mode at drift speeds around 3 cm/s and a short tail toward higher speeds. Another class shows a more even frequency distribution with large probability of drift speeds of 10 to 20 cm/s. Observations clearly agree better with the first class of model results.  Reasons for these differences lie in discrepancies in sea ice model characteristics and sea ice-ocean coupling.  In general, the models are capable of producing realistic drift pattern variability.  The winter of 1994/1995 stands out because of its maximum in Fram Strait ice export. While export estimates of some models agree with observations, the corresponding inner Arctic drift pattern is not reproduced. GOAL 1

Sea surface height/sea level Several improvements are needed to reduce model errors: Minimum model depth has to be less than 10 m. Minimum model depth has to be less than 10 m. Take into account: atmospheric loading, fast ice, and volume water fluxes representing Bering Strait inflow and river runoff. Take into account: atmospheric loading, fast ice, and volume water fluxes representing Bering Strait inflow and river runoff.  Sea level rise for 1954–2006 is estimated as cm/yr.  The sea level dropped significantly after 1990 and increased after the circulation regime changed from cyclonic to anticyclonic in In contrast, from 2000 to 2006 the sea level rose despite the stabilization of the AO index at its lowest values after GOAL 1

Tidal dynamics of water and sea ice A three-dimensional coupled ocean/ice model, intended for long-term Arctic climate studies, is extended to include tidal effects. From saved output of an Arctic tides model;  A three-dimensional coupled ocean/ice model, intended for long-term Arctic climate studies, is extended to include tidal effects. From saved output of an Arctic tides model;  We introduce parameterizations for: (1) enhanced ocean mixing associated with tides; and (1) enhanced ocean mixing associated with tides; and (2) the role of tides fracturing and mobilizing sea ice. (2) the role of tides fracturing and mobilizing sea ice. GOAL 1

Circulation patterns and tidal effects Holloway, G., and A. Proshutinsky (2007), Role of tides in Arctic ocean/ice climate, J. Geophys. Res., 112, C04S06, doi: /2006JC GOAL 1

Upper left: Potential temperature (°C) is shown at 320 m during December 1999 from a case without tides. Upper right: Temperature (°C), without tides, is shown on the vertical section marked by a green bar in the upper left panel. Lower right: Temperature (°C) is shown on the same vertical section, with the same color scale, as upper right but here including effects of tides Lower right: Temperature (°C) is shown on the same vertical section, with the same color scale, as upper right but here including effects of tides Lower left: The difference of temperature (°C) with tides and without tides Temperature (°C), without tides Temperature (°C), with tides Temperature difference with tides and without tides Holloway, G., and A. Proshutinsky (2007), Role of tides in Arctic ocean/ice climate, J. Geophys. Res., 112, C04S06, doi: /2006JC GOAL 1

Tidal effect results  Results show tides enhancing loss of heat from Atlantic waters.  The impact of tides on sea ice is more subtle as thinning due to enhanced ocean heat flux competes with net ice growth during rapid openings and closings of tidal leads.  Present model results are compared with an ensemble of nine AOMIP models.  Among results from AOMIP is a tendency for models to accumulate excessive Arctic Ocean heat throughout the intercomparison period 1950 to 2000 which is contrary to observations. Tidally induced ventilation of ocean heat reduces this discrepancy. GOAL 1

Atlantic Water circulation There are several scientific questions associated with the origin, direction, and variability of the Atlantic water layer circulation in the Arctic Ocean. Observational studies suggest that this circulation is cyclonic and its intensity may change depending on Arctic Oscillation or North Atlantic Oscillation regime. How surface forced ocean regulates circulation in deep layers is not clear. Figures above suggest that deep circulation does not change significantly when surface circulation changes from anticyclonic to cyclonic. GOAL 2

Models with cyclonic circulation of Atlantic water MOM high resolution POM MOM low resolution MOM Global, OPA AOMIP studies showed that some models generate cyclonic circulation which intensity changes in time insignificantly. Other model results show that circulation changes and even may reverse its direction. What is the origin of these reversals? GOAL 2

Models with anticyclonic circulation of Atlantic layer MOM high resolution Finite elements MOM Several models showed that the Atlantic water circulation is very stable and is anticyclonic!!! Note that model forcing, initial conditions, bathymetry, etc. were identical in the models reproduced cyclonic and anticyclonic motion of the Atlantic water. GOAL 2

Monthly mean potential temperature (°C) is shown as a function of depth and time for models AWI, CNF, GSFC, ICMMG, IOS, LANL, NPS, UL and UW averaged over subdomain “E”. AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

Monthly mean potential temperature (°C) is shown as a function of depth and time for models AWI, CNF, GSFC, ICMMG, IOS, LANL, NPS, UL and UW averaged over subdomain “A”. AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

Symbols identify the models. AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

Total heat referenced to 0°C, integrated over the volume of subdomain “E”, is plotted in units of 1022 J. Horizontal lines during the 1970s and 1980s are decadal mean heat for subdomain “E” from EWG [1997, 1998] summer and winter atlases.

Total heat referenced to 0°C, integrated over the volume of subdomain “A”, is plotted in units of 1022 J. Horizontal lines during the 1970s and 1980s are decadal mean heat for subdomain “A” from EWG [1997, 1998] summer and winter atlases AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

Monthly mean salinity is shown as a function of depth and time for models AWI, CNF, GSFC, ICMMG, IOS, LANL, UL, NPS and UW averaged over sub-domain “E” (left) and “A” - right E sub-domain A sub-domain AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA. Total freshwater referenced to S = 34.8 (including negative contributions when S > 34.8) is plotted in units of 10^13 m^3. Horizontal lines during the 1970s and 1980s are decadal mean freshwater from EWG [1997, 1998] summer and winter atlases integrated over the volume of sub-domain “E” (left) and A (right)

Neptune: Circulation and Topostrophy Flow (left) and topostrophy (right) is shown over bathymetry during December 1987 from IOS model, using neptune (top) and without neptune (bottom). Red and yellow – positive topostrophy and cyclonic motion. Blue – anticyclonic motion

Monthly mean normalized topostrophy is shown as a function of depth and time for sub-domains “E” (left) and “A” (right). AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

Normalized topostrophy (dimensionless) averaged over the volume of sub-domains “E” (left) and “A” (right) AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

Speed of monthly mean flow averaged over sub- domains “E” and “A” AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

Total kinetic energy of monthly mean flows is plotted in units of 1014 J integrated over the volume of subdomain “E”. AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

Averages of models' summer (July, August, September) and winter (March, April, May) temperatures, averaged from 1980 through 1989, are compared with the average of EWG summer and winter atlases (solid trace), 1980s decadal mean. AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

Lateral area (10 12 m 2 ) is plotted vs. depth (m) for the Amerasian and Eurasian basins. AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.

Root mean square slope is plotted vs. depth (m) for the Amerasian and Eurasian basins. AWI - Alfred Wegener Institute, POL –Proudman Oceanog Lab., UK Holloway, G., et al. (2007), Water properties CNF – FRCC/IARC, GSFC - Goddard Space Flight Center and circulation in Arctic Ocean models, J. Geophysical ICMMG – Russia, IOS -Institute of Ocean Sciences Res., 112, C04S03, doi: /2006JC LANL -Los Alamos, NPS - Naval Postgraduate School, USA; UL - Universite Laval, UW - University of Washington, USA.