Pleistocene epilithic foraminifera from the Arctic Ocean

Attached epilithic foraminifera constitute an important but overlooked component of the benthic foraminiferal assemblage in the Pleistocene sediment of the central Arctic Ocean. We report 12 types of epilithic foraminifera that have colonised lithic and biogenic grains found in glacial sediments, including representatives of the genera Rhizammina, Hemisphaerammina, Ammopemphix, Diffusilina, Subreophax, Placopsilina, Placopsilinella, Hormosinelloides and Tholosina, accompanied by mat-like and ribbon-like forms of uncertain taxonomic affinity. The attached agglutinated forms appear to be colonisers, adapted to extremely oligotrophic conditions.

Download Full-text

Arctic Ocean State-Changes: Self Interests and Common Interests

The Yearbook of Polar Law Online ◽

10.1163/22116427-91000026 ◽

2009 ◽

Vol 1 (1) ◽

pp. 511-525

Author(s):

Paul Arthur Berkman

Keyword(s):

Arctic Ocean ◽

The Arctic ◽

International Governance ◽

State Change ◽

Central Arctic Ocean ◽

Nation States ◽

Free Region ◽

The Arctic Ocean ◽

Challenges And Opportunities ◽

State Changes

Abstract Environmental and geopolitical state-changes are the underlying first principles of the diverse stakeholder positioning in the Arctic Ocean. The Arctic Ocean is changing from an ice-covered region to an ice-free region during the summer, which is an environmental state-change. As provided under the framework of the United Nations Convention on the Law of the Sea (UNCLOS), the central Arctic Ocean currently involves “High-Seas” (beyond the “Exclusive Economic Zones”) and the underlying “Area” of the deep-sea floor (beyond the “Continental Shelves”). Governance applications of this ‘donut’ demography – with international space surrounded by sovereign sectors – would be a geopolitical state-change in the Arctic Ocean. International governance strategies and applications for the central Arctic Ocean have far-reaching implications for the stewardship of other international spaces, which between Antarctica and the ocean beyond national jurisdictions account for nearly 75 percent of the Earth’s surface. In view of planetary-scale strategies for humankind, with frameworks such as climate, the Arctic Ocean underscores the challenges and opportunities to balance the governance of nation states and international spaces centuries into the future.

Download Full-text

Sediment archives from the Arctic Ocean provide evidence for massive remobilization of permafrost carbon in Siberia during the last glacial termination

10.5194/egusphere-egu2020-18643 ◽

2020 ◽

Author(s):

Jannik Martens ◽

Birgit Wild ◽

Tommaso Tesi ◽

Francesco Muschitiello ◽

Matt O’Regan ◽

...

Keyword(s):

Arctic Ocean ◽

Large Scale ◽

Sediment Cores ◽

The Arctic ◽

Last Deglaciation ◽

Central Arctic Ocean ◽

Last Glacial ◽

The Arctic Ocean ◽

Siberian Shelf ◽

The Last Glacial

Environmental archives and carbon cycle models suggest that climate warming during the last deglaciation (the transition from the last glacial to the Holocene) caused large-scale thaw of Arctic permafrost, followed by the release of previously freeze-locked carbon. In addition to changing oceanic circulation and outgassing of CO2 trapped in the deep glacial ocean, organic carbon (OC) release from thawing permafrost might have contributed to the rise in atmospheric CO2 by 80 ppmv or ~200 Pg C between 17.5 and 11.7 kyr before present (BP). The few Arctic sediment cores to date, however, lack either temporal resolution or reflect only regional catchments, leaving most of the permafrost OC remobilization of the deglaciation unconstrained.Our study explores the flux and fate of OC released from permafrost to the Siberian Arctic Seas during the last deglaciation. The Arctic Ocean is the main recipient of permafrost material delivered by river transport or collapse of coastal permafrost, providing an archive for current and past release of OC from thawing permafrost. We studied isotopes (&#916;14C-OC, &#948;13C-OC) and terrestrial biomarkers (CuO-derived lignin phenols, n-alkanes, n-alkanoic acids) in a number of sediment cores from the Siberian Shelf and Central Arctic Ocean to reconstruct source and fate of OC previously locked in permafrost.The composite record of three cores from the Laptev, East Siberian and Chukchi Seas suggest a combination of OC released by deepening of permafrost active layer in inland Siberia and by thermal collapse of coastal permafrost during the deglaciation. Coastal erosion of permafrost during the deglaciation suggests that sea-level rise and flooding of the Siberian shelf remobilized OC from permafrost deposits that covered the dry shelf areas during the last glacial. A sediment core from the Central Arctic Ocean demonstrates that this occurred in two major pulses; i) during the B&#248;lling-Aller&#248;d (14.7-12.9 kyr BP), but most strongly ii) during the early Holocene (11-7.6 kyr BP). In the early Holocene, flooding of 80% of the Siberian shelf amplified permafrost OC release to the Arctic Ocean, with peak fluxes 10-9 kyr BP one order of magnitude higher than at other times in the Holocene.It is likely that the remobilization of permafrost OC by flooding of the Siberian shelf released climate-significant amounts of dormant OC into active biogeochemical cycling and the atmosphere. Previous studies estimated that a pool of 300-600 Pg OC was held in permafrost covering Arctic Ocean shelves during the last glacial maximum; one can only speculate about its whereabouts after the deglaciation. Present und future reconstructions of historical remobilization of permafrost OC will help to understand how important permafrost thawing is to large-scale carbon cycling.

Download Full-text

Does the Summer Arctic Frontal Zone Influence Arctic Ocean Cyclone Activity?

Journal of Climate ◽

10.1175/jcli-d-15-0755.1 ◽

2016 ◽

Vol 29 (13) ◽

pp. 4977-4993 ◽

Cited By ~ 25

Author(s):

Alex D. Crawford ◽

Mark C. Serreze

Keyword(s):

Arctic Ocean ◽

Large Scale ◽

Frontal Zone ◽

External Source ◽

The Arctic ◽

Cyclone Activity ◽

Central Arctic Ocean ◽

The Arctic Ocean ◽

Summer Maximum ◽

Horizontal Temperature Gradients

Abstract Extratropical cyclone activity over the central Arctic Ocean reaches its peak in summer. Previous research has argued for the existence of two external source regions for cyclones contributing to this summer maximum: the Eurasian continent interior and a narrow band of strong horizontal temperature gradients along the Arctic coastline known as the Arctic frontal zone (AFZ). This study incorporates data from an atmospheric reanalysis and an advanced cyclone detection and tracking algorithm to critically evaluate the relationship between the summer AFZ and cyclone activity in the central Arctic Ocean. Analysis of both individual cyclone tracks and seasonal fields of cyclone characteristics shows that the Arctic coast (and therefore the AFZ) is not a region of cyclogenesis. Rather, the AFZ acts as an intensification area for systems forming over Eurasia. As these systems migrate toward the Arctic Ocean, they experience greater deepening in situations when the AFZ is strong at midtropospheric levels. On a broader scale, intensity of the summer AFZ at midtropospheric levels has a positive correlation with cyclone intensity in the Arctic Ocean during summer, even when controlling for variability in the northern annular mode. Taken as a whole, these findings suggest that the summer AFZ can intensify cyclones that cross the coast into the Arctic Ocean, but focused modeling studies are needed to disentangle the relative importance of the AFZ, large-scale circulation patterns, and topographic controls.

Download Full-text

The Summer Cyclone Maximum over the Central Arctic Ocean

Journal of Climate ◽

10.1175/2007jcli1810.1 ◽

2008 ◽

Vol 21 (5) ◽

pp. 1048-1065 ◽

Cited By ~ 111

Author(s):

Mark C. Serreze ◽

Andrew P. Barrett

Keyword(s):

Arctic Ocean ◽

High Latitude ◽

The Arctic ◽

Central Arctic Ocean ◽

Middle Latitudes ◽

The North ◽

The Arctic Ocean ◽

Northern High Latitude ◽

Separate Region ◽

Summer Maximum

Abstract A fascinating feature of the northern high-latitude circulation is a prominent summer maximum in cyclone activity over the Arctic Ocean, centered near the North Pole in the long-term mean. This pattern is associated with the influx of lows generated over the Eurasian continent and cyclogenesis over the Arctic Ocean itself. Its seasonal onset is linked to the following: an eastward shift in the Urals trough, migration of the 500-hPa vortex core to near the pole, and development of a separate region of high-latitude baroclinicity. The latter two features are consistent with differential atmospheric heating between the Arctic Ocean and snow-free land. Variability in the strength of the cyclone pattern can be broadly linked to the phase of the summer northern annular mode. When the cyclone pattern is well developed, the 500-hPa vortex is especially strong and symmetric about the pole, with negative sea level pressure (SLP) anomalies over the pole and positive anomalies over middle latitudes. Net precipitation tends to be anomalously positive over the Arctic Ocean. When poorly developed, the opposite holds.

Download Full-text

Separating individual contributions of major Siberian rivers in the Transpolar Drift of the Arctic Ocean

Scientific Reports ◽

10.1038/s41598-021-86948-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ronja Paffrath ◽

Georgi Laukert ◽

Dorothea Bauch ◽

Michiel Rutgers van der Loeff ◽

Katharina Pahnke

Keyword(s):

Arctic Ocean ◽

The Arctic ◽

Lateral Separation ◽

Central Arctic Ocean ◽

Siberian River ◽

Neodymium Isotopes ◽

The Arctic Ocean ◽

Individual Contributions ◽

Transpolar Drift ◽

The Individual

AbstractThe Siberian rivers supply large amounts of freshwater and terrestrial derived material to the Arctic Ocean. Although riverine freshwater and constituents have been identified in the central Arctic Ocean, the individual contributions of the Siberian rivers to and their spatiotemporal distributions in the Transpolar Drift (TPD), the major wind-driven current in the Eurasian sector of the Arctic Ocean, are unknown. Determining the influence of individual Siberian rivers downstream the TPD, however, is critical to forecast responses in polar and sub-polar hydrography and biogeochemistry to the anticipated individual changes in river discharge and freshwater composition. Here, we identify the contributions from the largest Siberian river systems, the Lena and Yenisei/Ob, in the TPD using dissolved neodymium isotopes and rare earth element concentrations. We further demonstrate their vertical and lateral separation that is likely due to distinct temporal emplacements of Lena and Yenisei/Ob waters in the TPD as well as prior mixing of Yenisei/Ob water with ambient waters.

Download Full-text

Cyclone impact on sea ice in the central Arctic Ocean: a statistical study

The Cryosphere ◽

10.5194/tc-8-303-2014 ◽

2014 ◽

Vol 8 (1) ◽

pp. 303-317 ◽

Cited By ~ 15

Author(s):

A. Kriegsmann ◽

B. Brümmer

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Ocean Model ◽

The Arctic ◽

Central Arctic Ocean ◽

Cumulative Impact ◽

Model Composite ◽

Ice Melt ◽

The Arctic Ocean ◽

The Impact

Abstract. This study investigates the impact of cyclones on the Arctic Ocean sea ice for the first time in a statistical manner. We apply the coupled ice–ocean model NAOSIM which is forced by the ECMWF analyses for the period 2006–2008. Cyclone position and radius detected in the ECMWF data are used to extract fields of wind, ice drift, and concentration from the ice–ocean model. Composite fields around the cyclone centre are calculated for different cyclone intensities, the four seasons, and different sub-regions of the Arctic Ocean. In total about 3500 cyclone events are analyzed. In general, cyclones reduce the ice concentration in the order of a few percent increasing towards the cyclone centre. This is confirmed by independent AMSR-E satellite data. The reduction increases with cyclone intensity and is most pronounced in summer and on the Siberian side of the Arctic Ocean. For the Arctic ice cover the cumulative impact of cyclones has climatologic consequences. In winter, the cyclone-induced openings refreeze so that the ice mass is increased. In summer, the openings remain open and the ice melt is accelerated via the positive albedo feedback. Strong summer storms on the Siberian side of the Arctic Ocean may have been important contributions to the recent ice extent minima in 2007 and 2012.

Download Full-text

Cyclone impact on sea ice in the central Arctic Ocean: a statistical study

The Cryosphere Discussions ◽

10.5194/tcd-7-1141-2013 ◽

2013 ◽

Vol 7 (2) ◽

pp. 1141-1176 ◽

Cited By ~ 3

Author(s):

A. Kriegsmann ◽

B. Brümmer

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Ocean Model ◽

The Arctic ◽

Central Arctic Ocean ◽

Model Composite ◽

Ice Melt ◽

The Arctic Ocean ◽

Arctic Ice ◽

The Impact

Abstract. This study investigates the impact of cyclones on the Arctic Ocean sea ice for the first time in a statistical manner. We apply the coupled ice–ocean model NAOSIM which is forced by the ECMWF analyses for the period 2006–2008. Cyclone position and radius detected in the ECMWF data are used to extract fields of wind, ice drift, and concentration from the ice–ocean model. Composite fields around the cyclone centre are calculated for different cyclone intensities, the four seasons, and different regions of the Arctic Ocean. In total about 3500 cyclone events are analyzed. In general, cyclones reduce the ice concentration on the order of a few percent increasing towards the cyclone centre. This is confirmed by independent AMSR-E satellite data. The reduction increases with cyclone intensity and is most pronounced in summer and on the Siberian side of the Arctic Ocean. For the Arctic ice cover the impact of cyclones has climatologic consequences. In winter, the cyclone-induced openings refreeze so that the ice mass is increased. In summer, the openings remain open and the ice melt is accelerated via the positive albedo feedback. Strong summer storms on the Siberian side of the Arctic Ocean may have been important reasons for the recent ice extent minima in 2007 and 2012.

Download Full-text

Meteorological and cloud conditions during the Arctic Ocean 2018 expedition

10.5194/acp-2020-219 ◽

2020 ◽

Author(s):

Jutta Vüllers ◽

Peggy Achtert ◽

Ian M. Brooks ◽

Michael Tjernström ◽

John Prytherch ◽

...

Keyword(s):

Arctic Ocean ◽

High Frequency ◽

Mixed Boundary ◽

The Arctic ◽

Atmospheric Conditions ◽

Central Arctic Ocean ◽

Surface Exchange ◽

Surface Water Chemistry ◽

Near Surface ◽

The Arctic Ocean

Abstract. The Arctic Ocean 2018 (AO2018) expedition took place in the central Arctic Ocean in August and September 2018. An extensive suite of instrumentation provided detailed measurements of surface water chemistry and biology, sea ice and ocean physical and biogeochemical properties, surface exchange processes, aerosols, clouds, and the state of the atmosphere. The measurements provide important information on the coupling of the ocean and ice surface to the atmosphere and in particular to clouds. This paper provides: (i) an overview of the synoptic-scale atmospheric conditions and its climatological anomaly to help interpret the process studies and put the detailed observations from AO2018 into a larger context, both spatially and temporally; (ii) a statistical analysis of the thermodynamic and near-surface meteorological conditions, boundary layer, cloud, and fog characteristics; (iii) a comparison of the results to observations from earlier Arctic Ocean expeditions, in particular AOE96, SHEBA, AOE2001, ASCOS, ACSE, and AO2016, to provide an assessment of the representativeness of the measurements. The results show that near-surface conditions were broadly comparable to earlier experiments, however the thermodynamic vertical structure was quite different. An unusually high frequency of well-mixed boundary layers up to about 1 km depth occurred, and only a few cases of the prototypical Arctic summer single-layer stratocumulus deck were observed. Instead, an unexpectedly high amount of multiple cloud layers and mid-level clouds was present throughout the campaign. These differences from previous studies are related to the high frequency of cyclonic activity in the central Arctic in 2018.

Download Full-text

Arctic Ocean Freshwater Changes over the Past 100 Years and Their Causes

Journal of Climate ◽

10.1175/2007jcli1748.1 ◽

2008 ◽

Vol 21 (2) ◽

pp. 364-384 ◽

Cited By ~ 76

Author(s):

I. V. Polyakov ◽

V. A. Alexeev ◽

G. I. Belchansky ◽

I. A. Dmitrenko ◽

V. V. Ivanov ◽

...

Keyword(s):

Arctic Ocean ◽

Observational Data ◽

Thermohaline Circulation ◽

Atmospheric Precipitation ◽

The Arctic ◽

Central Basin ◽

Central Arctic Ocean ◽

The Arctic Ocean ◽

Long Term Variations

Abstract Recent observations show dramatic changes of the Arctic atmosphere–ice–ocean system. Here the authors demonstrate, through the analysis of a vast collection of previously unsynthesized observational data, that over the twentieth century the central Arctic Ocean became increasingly saltier with a rate of freshwater loss of 239 ± 270 km3 decade−1. In contrast, long-term (1920–2003) freshwater content (FWC) trends over the Siberian shelf show a general freshening tendency with a rate of 29 ± 50 km3 decade−1. These FWC trends are modulated by strong multidecadal variability with sustained and widespread patterns. Associated with this variability, the FWC record shows two periods in the 1920s–30s and in recent decades when the central Arctic Ocean was saltier, and two periods in the earlier century and in the 1940s–70s when it was fresher. The current analysis of potential causes for the recent central Arctic Ocean salinification suggests that the FWC anomalies generated on Arctic shelves (including anomalies resulting from river discharge inputs) and those caused by net atmospheric precipitation were too small to trigger long-term FWC variations in the central Arctic Ocean; to the contrary, they tend to moderate the observed long-term central-basin FWC changes. Variability of the intermediate Atlantic Water did not have apparent impact on changes of the upper–Arctic Ocean water masses. The authors’ estimates suggest that ice production and sustained draining of freshwater from the Arctic Ocean in response to winds are the key contributors to the salinification of the upper Arctic Ocean over recent decades. Strength of the export of Arctic ice and water controls the supply of Arctic freshwater to subpolar basins while the intensity of the Arctic Ocean FWC anomalies is of less importance. Observational data demonstrate striking coherent long-term variations of the key Arctic climate parameters and strong coupling of long-term changes in the Arctic–North Atlantic climate system. Finally, since the high-latitude freshwater plays a crucial role in establishing and regulating global thermohaline circulation, the long-term variations of the freshwater content discussed here should be considered when assessing climate change and variability.

Download Full-text

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

Radiocarbon ◽

10.1017/s003382220001451x ◽

1994 ◽

Vol 36 (3) ◽

pp. 327-343 ◽

Cited By ~ 37

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.

Download Full-text