scholarly journals Deep-Water Flow over the Lomonosov Ridge in the Arctic Ocean

2005 ◽  
Vol 35 (8) ◽  
pp. 1489-1493 ◽  
Author(s):  
M-L. Timmermans ◽  
P. Winsor ◽  
J. A. Whitehead
Keyword(s):  
Arctic Ocean ◽  
Deep Water ◽  
Thermohaline Circulation ◽  
Global Climate ◽  
Volume Flow Rate ◽  
The Arctic ◽  
Lomonosov Ridge ◽  
Geothermal Heat ◽  
The Arctic Ocean ◽  
Canadian Basin

Abstract The Arctic Ocean likely impacts global climate through its effect on the rate of deep-water formation and the subsequent influence on global thermohaline circulation. Here, the renewal of the deep waters in the isolated Canadian Basin is quanitified. Using hydraulic theory and hydrographic observations, the authors calculate the magnitude of this renewal where circumstances have thus far prevented direct measurements. A volume flow rate of Q = 0.25 ± 0.15 Sv (Sv ≡ 106 m3 s−1) from the Eurasian Basin to the Canadian Basin via a deep gap in the dividing Lomonosov Ridge is estimated. Deep-water renewal time estimates based on this flow are consistent with 14C isolation ages. The flow is sufficiently large that it has a greater impact on the Canadian Basin deep water than either the geothermal heat flux or diffusive fluxes at the deep-water boundaries.

scholarly journals Evolution of the Deep Water in the Canadian Basin in the Arctic Ocean

2006 ◽  
Vol 36 (5) ◽  
pp. 866-874 ◽  
Author(s):  
M-L. Timmermans ◽  
Chris Garrett
Keyword(s):  
Arctic Ocean ◽  
Deep Water ◽  
Bottom Layer ◽  
Canada Basin ◽  
The Arctic ◽  
Lomonosov Ridge ◽  
Geothermal Heat ◽  
Makarov Basin ◽  
The Arctic Ocean ◽  
Canadian Basin

Abstract An overflow of magnitude 0.25 Sv (Sv ≡ 106 m−3 s−1) has been predicted to enter the Makarov Basin (part of the Canadian Basin in the Arctic Ocean) from the Eurasian Basin via a deep gap in the dividing Lomonosov ridge. The authors argue that this overflow does not ventilate the deep Makarov Basin (below 2400 m) where the water is too warm and salty to be compatible with such a large cold fresh inflow. However, complete isolation of the homogeneous bottom layer of the Makarov Basin must be ruled out because changes there are too small to arise from more than a small fraction of the measured geothermal heat flux into the basin. A small cold fresh inflow of about 0.01 Sv from the Amundsen Basin seems to be required. This could occur if the gap in the dividing Lomonosov Ridge is shallower than previously thought. It could also occur if there is active mixing and dilution of the predicted overflow in the gap, leaving only a small fraction to descend into the deep Makarov Basin. Hydraulic theory and hydrographic observations are used to rule out any significant flow of dense water from the Makarov Basin into the deep Canada Basin, confirming previous hypotheses of isolation of the deep water in the Canada Basin.

scholarly journals On the 14C and 39Ar Distribution in the Central Arctic Ocean: Implications for Deep Water Formation

Radiocarbon ◽  
1994 ◽  
Vol 36 (3) ◽  
pp. 327-343 ◽  
Author(s):  
Peter Schlosser ◽  
Bernd Kromer ◽  
Gote Östlund ◽  
Brenda Ekwurzel ◽  
Gerhard Bönisch ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Deep Water ◽  
Atlantic Water ◽  
The Arctic ◽  
Central Arctic Ocean ◽  
Deep Waters ◽  
The Arctic Ocean ◽  
Bottom Waters ◽  
Eurasian Basin ◽  
Canadian Basin

We present ΔA14C and 39Ar data collected in the Nansen, Amundsen and Makarov basins during two expeditions to the central Arctic Ocean (RV Polarstern cruises ARK IV/3, 1987 and ARK VIII/3, 1991). The data are used, together with published Δ14C values, to describe the distribution of Δ14C in all major basins of the Arctic Ocean (Nansen, Amundsen, Makarov and Canada Basins), as well as the 39Ar distribution in the Nansen Basin and the deep waters of the Amundsen and Makarov Basins. From the combined Δ14C and 39Ar distributions, we derive information on the mean “isolation ages” of the deep and bottom waters of the Arctic Ocean. The data point toward mean ages of the bottom waters in the Eurasian Basin (Nansen and Amundsen Basins) of ca. 250-300 yr. The deep waters of the Amundsen Basin show slightly higher 3H concentrations than those in the Nansen Basin, indicating the addition of a higher fraction of water that has been at the sea surface during the past few decades. Correction for the bomb 14C added to the deep waters along with bomb 3H yields isolation ages for the bulk of the deep and bottom waters of the Amundsen Basin similar to those estimated for the Nansen Basin. This finding agrees well with the 39Ar data. Deep and bottom waters in the Canadian Basin (Makarov and Canada Basins) are very homogeneous, with an isolation age of ca. 450 yr. Δ14C and 39Ar data and a simple inverse model treating the Canadian Basin Deep Water (CBDW) as one well-mixed reservoir renewed by a mixture of Atlantic Water (29%), Eurasian Basin Deep Water (69%) and brine-enriched shelf water (2%) yield a mean residence time of CBDW of ca. 300 yr.

scholarly journals Recent Trends in Freshwater Influx to the Arctic Ocean from Four Major Arctic-Draining Rivers

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1189 ◽  
Author(s):  
Roxanne Ahmed ◽  
Terry Prowse ◽  
Yonas Dibike ◽  
Barrie Bonsal ◽  
Hayley O’Neil
Keyword(s):  
Arctic Ocean ◽  
Thermohaline Circulation ◽  
Global Climate ◽  
Ocean Dynamics ◽  
The Arctic ◽  
Freshwater Input ◽  
Discharge Data ◽  
The Arctic Ocean ◽  
Spring Freshet ◽  
Daily Discharge

Runoff from Arctic rivers constitutes a major freshwater influx to the Arctic Ocean. In these nival-dominated river systems, the majority of annual discharge is released during the spring snowmelt period. The circulation regime of the salinity-stratified Arctic Ocean is connected to global earth–ocean dynamics through thermohaline circulation; hence, variability in freshwater input from the Arctic flowing rivers has important implications for the global climate system. Daily discharge data from each of the four largest Arctic-draining river watersheds (Mackenzie, Ob, Lena and Yenisei; herein referred to as MOLY) are analyzed to identify historic changes in the magnitude and timing of freshwater input to the Arctic Ocean with emphasis on the spring freshet. Results show that the total freshwater influx to the Arctic Ocean increased by 89 km3/decade, amounting to a 14% increase during the 30-year period from 1980 to 2009. A distinct shift towards earlier melt timing is also indicated by proportional increases in fall, winter and spring discharges (by 2.5%, 1.3% and 2.5% respectively) followed by a decrease (by 5.8%) in summer discharge as a percentage of the mean annual flow. This seasonal increase in discharge and earlier pulse onset dates indicates a general shift towards a flatter, broad-based hydrograph with earlier peak discharges. The study also reveals that the increasing trend in freshwater discharge to the Arctic Ocean is not solely due to increased spring freshet discharge, but is a combination of increases in all seasons except that of the summer.

Flow of Canadian basin deep water in the Western Eurasian Basin of the Arctic Ocean

2010 ◽  
Vol 57 (4) ◽  
pp. 577-586 ◽  
Author(s):  
Göran Björk ◽  
Leif G. Anderson ◽  
Martin Jakobsson ◽  
Dennis Antony ◽  
Björn Eriksson ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Deep Water ◽  
The Arctic ◽  
The Arctic Ocean ◽  
Eurasian Basin ◽  
Canadian Basin

Correlations between the Lomonosov Ridge, Marvin Spur and adjacent basins of the Arctic Ocean based on seismic data

2009 ◽  
Vol 472 (1-4) ◽  
pp. 309-322 ◽  
Author(s):  
A.E. Langinen ◽  
N.N. Lebedeva-Ivanova ◽  
D.G. Gee ◽  
Yu.Ya. Zamansky
Keyword(s):  
Arctic Ocean ◽  
Seismic Data ◽  
The Arctic ◽  
Lomonosov Ridge ◽  
The Arctic Ocean

scholarly journals Early to middle Eocene history of the Arctic Ocean from Nd-Sr isotopes in fossil fish debris, Lomonosov Ridge

2009 ◽  
Vol 24 (2) ◽  
pp. n/a-n/a ◽  
Author(s):  
J. D. Gleason ◽  
D. J. Thomas ◽  
T. C. Moore ◽  
J. D. Blum ◽  
R. M. Owen ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Middle Eocene ◽  
The Arctic ◽  
Lomonosov Ridge ◽  
Sr Isotopes ◽  
Fossil Fish ◽  
The Arctic Ocean ◽  
History Of

scholarly journals Natural variability of the Arctic Ocean sea ice during the present interglacial

2020 ◽  
Vol 117 (42) ◽  
pp. 26069-26075
Author(s):  
Anne de Vernal ◽  
Claude Hillaire-Marcel ◽  
Cynthia Le Duc ◽  
Philippe Roberge ◽  
Camille Brice ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Natural Variability ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Lomonosov Ridge ◽  
Arctic Sea ◽  
The Arctic Ocean ◽  
Open Question ◽  
The Impact

The impact of the ongoing anthropogenic warming on the Arctic Ocean sea ice is ascertained and closely monitored. However, its long-term fate remains an open question as its natural variability on centennial to millennial timescales is not well documented. Here, we use marine sedimentary records to reconstruct Arctic sea-ice fluctuations. Cores collected along the Lomonosov Ridge that extends across the Arctic Ocean from northern Greenland to the Laptev Sea were radiocarbon dated and analyzed for their micropaleontological and palynological contents, both bearing information on the past sea-ice cover. Results demonstrate that multiyear pack ice remained a robust feature of the western and central Lomonosov Ridge and that perennial sea ice remained present throughout the present interglacial, even during the climate optimum of the middle Holocene that globally peaked ∼6,500 y ago. In contradistinction, the southeastern Lomonosov Ridge area experienced seasonally sea-ice-free conditions, at least, sporadically, until about 4,000 y ago. They were marked by relatively high phytoplanktonic productivity and organic carbon fluxes at the seafloor resulting in low biogenic carbonate preservation. These results point to contrasted west–east surface ocean conditions in the Arctic Ocean, not unlike those of the Arctic dipole linked to the recent loss of Arctic sea ice. Hence, our data suggest that seasonally ice-free conditions in the southeastern Arctic Ocean with a dominant Arctic dipolar pattern, may be a recurrent feature under “warm world” climate.

scholarly journals Nudging the Arctic Ocean to Quantify Sea Ice Feedbacks

2019 ◽  
Vol 32 (8) ◽  
pp. 2381-2395
Author(s):  
Evelien Dekker ◽  
Richard Bintanja ◽  
Camiel Severijns
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Climate Sensitivity ◽  
Surface Albedo ◽  
Global Climate ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Climate Response ◽  
Arctic Sea ◽  
The Arctic Ocean

AbstractWith Arctic summer sea ice potentially disappearing halfway through this century, the surface albedo and insulating effects of Arctic sea ice will decrease considerably. The ongoing Arctic sea ice retreat also affects the strength of the Planck, lapse rate, cloud, and surface albedo feedbacks together with changes in the heat exchange between the ocean and the atmosphere, but their combined effect on climate sensitivity has not been quantified. This study presents an estimate of all Arctic sea ice related climate feedbacks combined. We use a new method to keep Arctic sea ice at its present-day (PD) distribution under a changing climate in a 50-yr CO2 doubling simulation, using a fully coupled global climate model (EC-Earth, version 2.3). We nudge the Arctic Ocean to the (monthly dependent) year 2000 mean temperature and minimum salinity fields on a mask representing PD sea ice cover. We are able to preserve about 95% of the PD mean March and 77% of the September PD Arctic sea ice extent by applying this method. Using simulations with and without nudging, we estimate the climate response associated with Arctic sea ice changes. The Arctic sea ice feedback globally equals 0.28 ± 0.15 W m−2 K−1. The total sea ice feedback thus amplifies the climate response for a doubling of CO2, in line with earlier findings. Our estimate of the Arctic sea ice feedback agrees reasonably well with earlier CMIP5 global climate feedback estimates and shows that the Arctic sea ice exerts a considerable effect on the Arctic and global climate sensitivity.

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