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2008
Jones, EP, Anderson LG, Jutterstrom S, Swift JH.  2008.  Sources and distribution of fresh water in the East Greenland Current. Progress in Oceanography. 78:37-44.   10.1016/j.pocean.2007.06.003   AbstractWebsite

Fresh water flowing from the Arctic Ocean via the East Greenland Current influences deep water formation in the Nordic Seas as well as the salinity of the surface and deep waters flowing from there. This fresh water has three sources: Pacific water (relatively fresh cf. Atlantic water), river runoff, and sea ice meltwater. To determine the relative amounts of the three sources of fresh water, in May 2002 we collected water samples across the East Greenland Current in sections from 81.5 degrees N to the Irminger Sea south of Denmark Strait. We used nitrate-phosphate relationships to distinguish Pacific waters from Atlantic waters, salinity to obtain the sum of sea ice melt water and river runoff water, and total alkalinity to distinguish the latter. River runoff contributed the largest part of the total fresh water component, in some regions with some inventories exceeding 12 m. Pacific fresh water (Pacific source water S similar to 32 cf Atlantic source water S similar to 34.9) typically provided about 1/3 of the river runoff contribution. Sea ice meltwater was very nearly non-existent in the surface waters of all sections, likely at least in part as a result of the samples being collected before the onset of the melt season. The fresh water from the Arctic Ocean was strongly confined to near the Greenland coast. We thus conjecture that the main source of fresh water from the Arctic Ocean most strongly impacting deep convection in the Nordic Seas would be sea ice as opposed to fresh water in the liquid phase, i.e., river runoff, Pacific fresh water, and sea ice meltwater. Crown Copyright (C) 2008 Published by Elsevier Ltd. All rights reserved.

Marnela, M, Rudels B, Olsson KA, Anderson LG, Jeansson E, Torres DJ, Messias MJ, Swift JH, Watson AJ.  2008.  Transports of Nordic Seas water masses and excess SF6 through Fram Strait to the Arctic Ocean. Progress in Oceanography. 78:1-11.   10.1016/j.pocean.2007.06.004   AbstractWebsite

To determine the exchanges between the Nordic Seas and the Arctic Ocean through Fram Strait is one of the most important aspects, and one of the major challenges, in describing the circulation in the Arctic Mediterranean Sea. Especially the northward transport of Arctic Intermediate Water (AIW) from the Nordic Seas into the Arctic Ocean is little known. In the two-ship study of the circulation in the Nordic Seas, Arctic Ocean - 2002, the Swedish icebreaker Oden operated in the ice-covered areas in and north of Fram Strait and in the western margins of Greenland and Iceland seas, while RV Knorr of Woods Hole worked in the ice free part of the Nordic Seas. Here two hydrographic sections obtained by Oden, augmented by tracer and velocity measurements with Lowered Acoustic Doppler Current Profiler (LADCP), are examined. The first section, reaching from the Svalbard shelf across the Yermak Plateau, covers the region north of Svalbard where inflow to the Arctic Ocean takes place. The second, western, section spans the outflow area extending from west of the Yermak Plateau onto the Greenland shelf. Geostrophic and LADCP derived velocities are both used to estimate the exchanges of water masses between the Nordic Seas and the Arctic Ocean. The geostrophic computations indicate a total flow of 3.6 Sv entering the Arctic on the eastern section. The southward flow on the western section is found to be 5.1 Sv. The total inflow to the Arctic Ocean obtained using the LADCP derived velocities is much larger, 13.6 Sv, and the southward transport on the western section is 13.7 Sv, equal to the northward transport north of Svalbard. Sulphur hexafluoricle (SF(6)) originating from a tracer release experiment in the Greenland Sea in 1996 has become a marker for the circulation of AIW. From the geostrophic velocities we obtain 0.5 Sv and from the LADCP derived velocities 2.8 Sv of AIW flowing into the Arctic. The annual transport of SF(6) into the Arctic Ocean derived from geostrophy is 5 kg/year, which is of the same magnitude as the observed total annual transport into the North Atlantic, while the LADCP measurements (19 kg/year) imply that it is substantially larger. Little SF(6) was found on the western section, confirming the dominance of the Arctic Ocean water masses and indicating that the major recirculation in Fram Strait takes place farther to the south. (C) 2008 Elsevier Ltd. All rights reserved.

2005
Falkner, KK, Steele M, Woodgate RA, Swift JH, Aagaard K, Morison J.  2005.  Dissolved oxygen extrema in the Arctic Ocean halocline from the North Pole to the Lincoln Sea. Deep-Sea Research Part I-Oceanographic Research Papers. 52:1138-1154.   10.1016/j.dsr.2005.01.007   AbstractWebsite

Dissolved oxygen (02) profiling by new generation sensors was conducted in the Arctic Ocean via aircraft during May 2003 as part of the North Pole Environmental Observatory (NPEO) and Freshwater Switchyard (SWYD) projects. At stations extending from the North Pole to the shelf off Ellesmere Island, such profiles display what appear to be various 02 maxima (with concentrations 70% of saturation or less) over depths of 70-110 m in the halocline, corresponding to salinity and temperature ranges of 33.3-33.9 and -1.7 to -1.5 degrees C. The features appear to be widely distributed: Similar features based on bottle data were recently reported for a subset of the 1997-1998 SHEBA stations in the southern Canada Basin and in recent Beaufort Sea sensor profiles. Oxygen sensor data from August 2002 Chukchi Borderlands (CBC) and 1994 Arctic Ocean Section (AOS) projects suggest that such features arise from interleaving of shelf-derived, O(2)-depleted waters. This generates apparent oxygen maxima in Arctic Basin profiles that would otherwise trend more smoothly from near-saturation at the surface to lower concentrations at depth. For example, in the Eurasian Basin, relatively low O(2) concentrations are observed at salinities of about 34.2 and 34.7. The less saline variant is identified as part of the lower halocline, a layer originally identified by a Eurasian Basin minimum in "NO," which, in the Canadian Basin, is reinforced by additional inputs. The more saline and thus denser variant appears to arise from transformations of Atlantic source waters over the Barents and/or Kara shelves. Additional low-oxygen waters are generated in the vicinity of the Chukchi Borderlands, from Pacific shelf water outflows that interleave with Eurasian waters that flow over the Lomonosov Ridge into the Makarov Basin and then into the Canada Basin. One such input is associated with the well-known silicate maximum that historically has been associated with a salinity of approximate to 33.1. Above that (32 < S < 33), there is a layer moderately elevated in temperature (summer Bering Sea water) that we show is also O(2)-depleted. We propose that these low O(2) waters influence the NPEO and SWYD profiles to varying extents in a manner reflective of the large-scale circulation. The patterns of halocline circulation we infer from the intrusive features defy a simple boundary-following cyclonic flow. These results demonstrate the value of the improved resolution made feasible with continuous O(2) Profiling. In the drive to better understand variability and change in the Arctic Ocean, deployment of appropriately calibrated CTD-O(2) packages offers the promise of important new insights into circulation and ecosystem function. (c) 2005 Elsevier Ltd. All rights reserved.

2001
Fransson, A, Chierici M, Anderson LC, Bussmann I, Kattner G, Jones EP, Swift JH.  2001.  The importance of shelf processes for the modification of chemical constituents in the waters of the Eurasian Arctic Ocean: implication for carbon fluxes. Continental Shelf Research. 21:225-242.   10.1016/s0278-4343(00)00088-1   AbstractWebsite

Carbon transformation along the Eurasian shelves in water of Atlantic origin is estimated. Nutrient, oxygen, and inorganic and organic carbon data were used in the evaluation. By comparing the relative deficit of the different chemical constituents it is possible to evaluate the transformation of carbon. It can be seen that the chemical signature in the shelf seas was modified extensively, corresponding to an export production from the upper 50 m in the Barents Sea of 28-32 g C m(-2), which is five times higher than that in the Kara-Laptev Seas and over the deep Eurasian basin. The difference in the export production, computed from the nutrient deficit, and the observed deficit of dissolved inorganic carbon is attributed air-sea exchange of CO2. With this approach the relative oceanic uptake of CO2 from the atmosphere was estimated to be 70% (44 g C m(-2)) in the Barents Sea and 15% (1 g C m(-2)) in the Kara-Laptev Seas, relative to the export production. Of the export production in the Barents Sea, about a quarter is found as DOC. The difference between the chemical signature at the Laptev Sea shelf slope and over the Lomonosov Ridge is negligible, which shows that the transformation of carbon is very small in the surface layers of the Eurasian basin. Combining the chemical transformation with reported volume transports gives an annual export production of 9.6 x 10(12) g C yr(-1) in the Barents Sea. The oceanic uptake of CO2 for the same area is 9.2 x 10(12) g C yr(-1). (C) 2001 Elsevier Science Ltd. All rights reserved.