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  • 1. Anderson, L G
    et al.
    Falck, E
    Jones, E P
    Jutterstrom, S
    Swift, J H
    Enhanced uptake of atmospheric CO2 during freezing of seawater: A field study in Storfjorden, Svalbard2004In: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 109, no C6Article in journal (Refereed)
    Abstract [en]

    The waters of Storfjorden, a fjord in southern Svalbard, were investigated in late April 2002. The temperature was at the freezing point throughout the water column; the salinity in the top 30 m was just above 34.8, then increased nearly linearly to about 35.8 at the bottom. Nutrient and oxygen concentrations showed a minimal trend all through the water column, indicating minimal decay of organic matter. Normalized dissolved inorganic carbon, fCO(2), and CFCs increase with depth below the surface mixed layer, while pH decreases. In waters below 50 m, there was an increase in dissolved inorganic carbon, corrected for decay of organic matter using the phosphate profile, corresponding to about 9 g C m(-2) relative to the surface water concentration. We suggest this excess is a result of enhanced air-sea exchange of CO2 caused by sea ice formation. This enhancement is suggested to be a result of an efficient exchange through the surface film during the ice crystal formation and the rapid transport of the high salinity brine out of the surface layer.

  • 2. Anderson, L G
    et al.
    Jutterstrom, S
    Kaltin, S
    Jones, E P
    Bjork, G R
    Variability in river runoff distribution in the Eurasian Basin of the Arctic Ocean2004In: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 109, no C1Article in journal (Refereed)
    Abstract [en]

    The distribution of freshwater within the Arctic Ocean and its export from it are intimately involved in climate and climate change processes both within and outside the Arctic Ocean. River runoff in the Arctic Ocean constitutes a major part of the Arctic Ocean freshwater budget. Within the Arctic Ocean, variability in the distribution of river runoff will be reflected in the location of the cold halocline that isolates the sea ice from the warm Atlantic Layer. Outside the Arctic Ocean, such variability will impact on the salinity of North Atlantic waters (Great Salinity Anomaly) and on deep convection areas of the North Atlantic Ocean, and thereby potentially on global thermohaline circulation. Rivers entering the Arctic Ocean have high levels of total alkalinity that contribute significantly to the total alkalinity of the surface Polar Mixed Layer. We exploit total alkalinity data to trace river runoff in the surface Polar Mixed Layer and to observe variability in the river runoff distribution in the Eurasian Basin over the period 1987-2001. The river runoff front changed from a position over the Gakkel Ridge in 1987 and 1991 to over the Lomonosov Ridge in 1996, and returned to a midpoint between the two ridges in 2001. Wind field changes as characterized by the Arctic Oscillation index are considered to be a major factor in determining ice and surface water flow. We note a correlation with 4-6 years delay between changes in river runoff distribution and the Arctic Oscillation index. We show that the delay can be inferred from a geostrophic flow calculation.

  • 3. Anderson, Leif G.
    et al.
    Andersson, Per S.
    Bjork, Goran
    Jones, E. Peter
    Jutterstrom, Sara
    Wahlstrom, Irene
    Source and formation of the upper halocline of the Arctic Ocean2013In: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 118, no 1, p. 410-421Article in journal (Refereed)
    Abstract [en]

    The upper halocline of the Arctic Ocean has a distinct chemical signature with high nutrient concentrations as well as low oxygen and pH values. This signature is formed in the Chukchi and East Siberian seas, by a combination of mineralization of organic matter and release of decay products to the sea ice brine enriched bottom water. Salinity and total alkalinity data show that the fraction of sea ice brine in the nutrient-enriched upper halocline water in the central Arctic Ocean is up to 4%. In the East Siberian Sea the bottom waters with exceptional high nutrient concentration and low pH have typically between 5 and 10% of sea ice brine as computed from salinity and oxygen-18 values. On the continental slope, over bottom depths of 150-200 m, the brine contribution was 6% at the nutrient maximum depth (50-100 m). At the same location as well as over the deeper basin the silicate maximum was found over a wider salinity range than traditionally found in the Canada Basin, in agreement with earlier observations east of the Chukchi Plateau. A detailed evaluation of the chemical and the temperature-salinity properties suggests at least two different areas for the formation of the nutrient-rich halocline within the East Siberian Sea. This has not been observed before 2004 and it could be a sign of a changing marine climate in the East Siberian Sea, caused by more open water in the summer season followed by more sea ice formation and brine production in the fall/winter. Citation: Anderson, L. G., P. S. Andersson, G. Bjork, E. Peter Jones, S. Jutterstrom, and I. Wahlstrom (2013), Source and formation of the upper halocline of the Arctic Ocean, J. Geophys. Res. Oceans, 118, 410-421, doi:10.1029/2012JC008291.

  • 4. Ericson, Ylva
    et al.
    Ulfsbo, Adam
    van Heuven, Steven
    Kattner, Gerhard
    Anderson, Leif G.
    Increasing carbon inventory of the intermediate layers of the Arctic Ocean2014In: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 119, no 4, p. 2312-2326Article in journal (Refereed)
    Abstract [en]

    Key Points <list id=”jgrc20638-list-0001” list-type=”bulleted”> <list-item id=”jgrc20638-li-0001”>Inorganic carbon concentration increase in intermediate water layers of the Arctic Ocean <list-item id=”jgrc20638-li-0002”>No significant trend in nutrient or oxygen concentrations was found <list-item id=”jgrc20638-li-0003”>Inflow of anthropogenic carbon to intermediate layers is the likely cause Abstract Concentrations of dissolved inorganic carbon (DIC), total alkalinity (TA), nutrients, and oxygen in subsurface waters of the central Arctic Ocean have been investigated for conceivable time trends over the last two decades. Data from six cruises (1991-2011) that cover the Nansen, Amundsen, and Makarov Basins were included in this analysis. In waters deeper than 2000 m, no statistically significant trend could be observed for DIC, TA, phosphate, or nitrate, but a small rate of increase in apparent oxygen utilization (AOU) was noticeable. For the individual stations, differences in concentration of each property were computed between the mean concentrations in the Arctic Atlantic Water (AAW) or the upper Polar Deep Water (uPDW), i.e., between about 150 and 1400 m depth, and in the deep water (assumed invariable over time). In these shallower water layers, we observe significant above-zero time trends for DIC, in the range of 0.6-0.9 mol kg(-1) yr(-1) (for AAW) and 0.4-0.6 mu mol kg(-1) yr(-1) (for uPDW). No time trend in nutrients could be observed, indicating no change in the rate of organic matter mineralization within this depth range. Consequently, the buildup of DIC is attributed to increasing concentrations of anthropogenic carbon in the waters flowing into these depth layers of the Arctic Ocean. The resulting rate of increase of the column inventory of anthropogenic CO2 is estimated to be between 0.6 and 0.9 mol C m(-2) yr(-1), with distinct differences between basins.

  • 5. Linders, Johanna
    et al.
    Bjork, Goran
    The melt-freeze cycle of the Arctic Ocean ice cover and its dependence on ocean stratification2013In: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 118, no 11, p. 5963-5976Article in journal (Refereed)
    Abstract [en]

    A time-dependent, 1-D coupled ice-ocean model is used to quantify the impact of ocean stratification on the Arctic ice cover. The model results show that the ice growth during winter equals the ice melt in summer for areas with a well-developed cold halocline layer (CHL), provided that the initial ice thickness is around 3 m, while thinner initial ice thickness results in net growth. Areas with weak salt stratification can have a negative annual thickness change irrespective of the initial ice thickness and are thus dependent on ice import in order to remain ice covered. The model results also show that ocean stratification is mostly important for ice-thickness development during the growing season. Areas with weak stratification have an ocean heat flux up to 8 W m(-2) reaching the ice during the growing season, while areas with a CHL have an average of about 0.7 W m(-2). In the extreme area, north of Svalbard, the ocean heat fluxes are typically around 25 W m(-2) but can be up to 400 W m(-2) during the initial adjustment, when the warm Atlantic water has direct contact with the ice. A general outcome of the study is that, depending on ocean stratification, the ice cover of Arctic Ocean can be divided into one part with net ice growth (the major part) and another part with net ice melt (mainly in the Nansen Basin).

  • 6.
    Rosen, Per-Olov
    et al.
    Swedish Museum Nat Hist, Dept Geosci, S-10405 Stockholm, Sweden.;Stockholm Univ, Dept Environm Sci & Analyt Chem, S-10691 Stockholm, Sweden..
    Andersson, Per S.
    Swedish Museum Nat Hist, Dept Geosci, S-10405 Stockholm, Sweden..
    Alling, Vanja
    Stockholm Univ, Dept Environm Sci & Analyt Chem, S-10691 Stockholm, Sweden.;Norwegian Environm Agcy, Oslo, Norway..
    Morth, Carl-Magnus
    Stockholm Univ, Dept Geol Sci, S-10691 Stockholm, Sweden..
    Bjork, Goran
    Univ Gothenburg, Dept Oceanog, Ctr Earth Sci, Gothenburg, Sweden..
    Semiletov, Igor
    Univ Alaska, Internat Arctic Res Ctr, Fairbanks, AK 99701 USA.;Russian Acad Sci, Pacific Oceanol Inst, Vladivostok 690022, Russia.;Natl Tomsk Res Polytechn Univ, Tomsk, Russia..
    Porcelli, Don
    Univ Oxford, Dept Earth Sci, Oxford, England..
    Ice export from the Laptev and East Siberian Sea derived from delta O-18 values2015In: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 120, no 9, p. 5997-6007Article in journal (Refereed)
    Abstract [en]

    Ice export from the vast Arctic Siberian shelf is calculated using O-18 values and salinity data for water samples collected during the International Siberian Shelf Study between August and September 2008 (ISSS-08). The samples represent a wide range of salinities and O-18 values due to river water inputs and sea ice removal. We estimate the fraction of water that has been removed as ice by interpreting observed O-18 values and salinities as a result of mixing between river water and sea water end-members as well as to fractional ice removal. This method does not assume an ice end-member of fixed composition, which is especially important when applied on samples with large differences in salinity. The results show that there is net transport of ice from both the Laptev and the Eastern Siberian Seas, and in total 3000 km(3) of sea ice is exported from the shelf. The annual total export of ice from the entire region, calculated from the residence time of water on the shelf, is estimated to be 860 km(3) yr(-1). Thus, changes in ice production on the shelf may have great impact on sea ice export from the Arctic Ocean.

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  • 7. Sedwick, P. N.
    et al.
    Marsay, C. M.
    Sohst, B. M.
    Aguilar-Islas, A. M.
    Lohan, M. C.
    Long, M. C.
    Arrigo, K. R.
    Dunbar, R. B.
    Saito, M. A.
    Smith, W. O.
    DiTullio, G. R.
    Early season depletion of dissolved iron in the Ross Sea polynya: Implications for iron dynamics on the Antarctic continental shelf2011In: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 116Article in journal (Refereed)
    Abstract [en]

    The Ross Sea polynya is among the most productive regions in the Southern Ocean and may constitute a significant oceanic CO2 sink. Based on results from several field studies, this region has been considered seasonally iron limited, whereby a “winter reserve” of dissolved iron (dFe) is progressively depleted during the growing season to low concentrations (similar to 0.1 nM) that limit phytoplankton growth in the austral summer (December-February). Here we report new iron data for the Ross Sea polynya during austral summer 2005-2006 (27 December-22 January) and the following austral spring 2006 (16 November-3 December). The summer 2005-2006 data show generally low dFe concentrations in polynya surface waters (0.10 +/- 0.05 nM in upper 40 m, n = 175), consistent with previous observations. Surprisingly, our spring 2006 data reveal similar low surface dFe concentrations in the polynya (0.06 +/- 0.04 nM in upper 40 m, n = 69), in association with relatively high rates of primary production (similar to 170-260 mmol C m(-2) d(-1)). These results indicate that the winter reserve dFe may be consumed relatively early in the growing season, such that polynya surface waters can become “iron limited” as early as November; i.e., the seasonal depletion of dFe is not necessarily gradual. Satellite observations reveal significant biomass accumulation in the polynya during summer 2006-2007, implying significant sources of “new” dFe to surface waters during this period. Possible sources of this new dFe include episodic vertical exchange, lateral advection, aerosol input, and reductive dissolution of particulate iron.

  • 8. Vonk, Jorien E.
    et al.
    Semiletov, Igor P.
    Dudarev, Oleg V.
    Eglinton, Timothy I.
    Andersson, August
    Shakhova, Natalia
    Charkin, Alexander
    Heim, Birgit
    Gustafsson, Orjan
    Preferential burial of permafrost-derived organic carbon in Siberian-Arctic shelf waters2014In: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 119, no 12, p. 8410-8421Article in journal (Refereed)
    Abstract [en]

    The rapidly changing East Siberian Arctic Shelf (ESAS) receives large amounts of terrestrial organic carbon (OC) from coastal erosion and Russian-Arctic rivers. Climate warming increases thawing of coastal Ice Complex Deposits (ICD) and can change both the amount of released OC, as well as its propensity to be converted to greenhouse gases (fueling further global warming) or to be buried in coastal sediments. This study aimed to unravel the susceptibility to degradation, and transport and dispersal patterns of OC delivered to the ESAS. Bulk and molecular radiocarbon analyses on surface particulate matter (PM), sinking PM and underlying surface sediments illustrate the active release of old OC from coastal permafrost. Molecular tracers for recalcitrant soil OC showed ages of 3.4-13 C-14-ky in surface PM and 5.5-18 C-14-ky in surface sediments. The age difference of these markers between surface PM and surface sediments is larger (i) in regions with low OC accumulation rates, suggesting a weaker exchange between water column and sediments, and (ii) with increasing distance from the Lena River, suggesting preferential settling of fluvially derived old OC nearshore. A dual-carbon end-member mixing model showed that (i) contemporary terrestrial OC is dispersed mainly by horizontal transport while being subject to active degradation, (ii) marine OC is most affected by vertical transport and also actively degraded in the water column, and (iii) OC from ICD settles rapidly and dominates surface sediments. Preferential burial of ICD-OC released into ESAS coastal waters might therefore lower the suggested carbon cycle climate feedback from thawing ICD permafrost.

  • 9. Wynn, J. G.
    et al.
    Robbins, L. L.
    Anderson, L. G.
    Processes of multibathyal aragonite undersaturation in the Arctic Ocean2016In: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 121, no 11, p. 8248-8267Article in journal (Refereed)
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