Publications

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2008
Jeansson, E, Jutterstroem S, Rudels B, Anderson LG, Olsson KA, Jones EP, Smethie WM, Swift JH.  2008.  Sources to the East Greenland Current and its contribution to the Denmark Strait Overflow. Progress in Oceanography. 78:12-28.   10.1016/j.pocean.2007.08.031   AbstractWebsite

Data from the East Greenland Current in 2002 are evaluated using optimum multiparameter analysis. The current is followed from north of Fram Strait to the Denmark Strait Sill and the contributions of different source waters, in mass fractions, are deduced. From the results it can be concluded that, at least in spring 2002, the East Greenland Current was the main source for the waters found at the Denmark Strait Sill, contributing to the overflow into the North Atlantic. The East Greenland Current carried water masses from different source regions in the Arctic Ocean, the West Spitsbergen Current and the Greenland Sea. The results agree well with the known circulation of the western Nordic Seas but also add knowledge both to the quantification and to the mixing processes, showing the importance of the locally formed Greenland Sea Arctic Intermediate Water for the East Greenland Current and the Denmark Strait. (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.

2004
McLaughlin, FA, Carmack EC, Macdonald RW, Melling H, Swift JH, Wheeler PA, Sherr BF, Sherr EB.  2004.  The joint roles of Pacific and Atlantic-origin waters in the Canada Basin, 1997-1998. Deep-Sea Research Part I-Oceanographic Research Papers. 51:107-128.   10.1016/j.dsr.2003.09.010   AbstractWebsite

Physical and geochemical data collected weekly during the year-long 2800 km drift of the CCGS des Groseilliers show that Canada Basin waters, and in particular the composition of the halocline, can no longer be viewed as laterally homogeneous and in steady state. The halocline was thinner over the Mendeleyev Abyssal Plain and northern Chukchi Plateau. Here, Pacific-origin upper and middle halocline waters occupied the upper 80m of the water column and underlying Atlantic-origin lower halocline waters were fresher, colder and much more ventilated than observed in the past. These new observations of a sub-surface oxygen maximum suggest that outflow from the East Siberian Sea now supplies the Canada Basin lower halocline. East of the Northwind Ridge the halocline was thicker and appeared relatively unchanged. Here Pacific-origin upper and middle halocline waters occupied the top 225 m and Atlantic-origin lower halocline waters were identified by an oxygen minimum. The intensity of the Pacific-origin signal, characterized by a nutrient maximum, was strongest over the Chukchi Gap-the passage between the Chukchi Shelf and Plateau-and the Northwind Abyssal Plain and identified two winter-water spreading pathways. Atlantic-origin waters as much as 0.5degreesC warmer than the historical record were observed over the Chukchi Gap and also over the northern flank of the Chukchi Plateau. These observations signaled that warm-anomaly Fram Strait Branch (FSB) waters, first observed upstream in the Nansen Basin in 1990, had arrived downstream in the Canada Basin eight years later and also indicate two routes whereby FSB waters enter the southern Canada Basin. Although samples were collected throughout one annual cycle, seasonal effects were small and confined to the upper 50 m of the water column. These data show Canada Basin waters are in transition, responding to the effects of upstream change in atmospheric and oceanic circulation. Crown Copyright (C) 2003 Published by Elsevier Ltd. All rights reserved.