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Anderson, LG, Falck E, Jones EP, Jutterstrom S, Swift JH.  2004.  Enhanced uptake of atmospheric CO2 during freezing of seawater: A field study in Storfjorden, Svalbard. Journal of Geophysical Research-Oceans. 109   10.1029/2003jc002120   AbstractWebsite

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 CO(2) 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.

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.

Anderson, LG, Jones EP, Swift JH.  2003.  Export production in the central Arctic Ocean evaluated from phosphate deficits. Journal of Geophysical Research-Oceans. 108   10.1029/2001jc001057   AbstractWebsite

[1] Primary productivity in the central Arctic Ocean has recently been reported as being much higher than earlier thought. If a significant fraction of this primary production were exported from the immediate surface region, present estimates of the carbon budget for the Arctic Ocean would have to be reassessed. Using the deficit of phosphate in the central Arctic Ocean, we show that the export production is very low, on an average less than 0.5 gC m(-2) yr(-1). This is at least an order of magnitude lower than the total production as measured or estimated from oxygen data, thus indicating extensive recycling of nutrients in the upper waters of the central Arctic Ocean and very little export production.

Jones, EP, Swift JH, Anderson LG, Lipizer M, Civitarese G, Falkner KK, Kattner G, McLaughlin F.  2003.  Tracing Pacific water in the North Atlantic Ocean. Journal of Geophysical Research-Oceans. 108   10.1029/2001jc001141   AbstractWebsite

[1] In the Arctic Ocean, Pacific source water can be distinguished from Atlantic source water by nitrate-phosphate concentration relationships, with Pacific water having higher phosphate concentrations relative to those of nitrate. Furthermore, Pacific water, originally from the inflow through Bering Strait, is clearly recognizable in the outflows of low-salinity waters from the Arctic Ocean to the northern North Atlantic Ocean through the Canadian Arctic Archipelago and through Fram Strait. In the Canadian Arctic Archipelago, we observe that almost all of the waters flowing through Lancaster and Jones sounds, most of the water in the top 100 m in Smith Sound (containing the flow through Nares Strait), and possibly all waters in Hudson Bay contain no water of Atlantic origin. Significant amounts of Pacific water are also observed along the western coast of Baffin Bay, along the coast of Labrador, and above the 200-m isobath of the Grand Banks. There is a clear signal of Pacific water flowing south through Fram Strait and along the east coast of Greenland extending at least as far south as Denmark Strait. Pacific water signature can be seen near the east coast of Greenland at 66degreesN, but not in data at 60degreesN. Temporal variability in the concentrations of Pacific water has been observed at several locations where multiple-year observations are available.

Schauer, U, Rudels B, Jones EP, Anderson LG, Muench RD, Bjork G, Swift JH, Ivanov V, Larsson AM.  2002.  Confluence and redistribution of Atlantic water in the Nansen, Amundsen and Makarov basins. Annales Geophysicae. 20:257-273.   10.5194/angeo-20-257-2002   AbstractWebsite

The waters in the Eurasian Basin are conditioned by the confluence of the boundary flow of warm, saline Fram Strait water and cold low salinity water from the Barents Sea entering through the St. Anna Trough. Hydrographic sections obtained from RV Polarstern during the summer of 1996 (ACSYS 96) across the St. Anna Trough and the Voronin Trough in the northern Kara Sea and across the Nansen, Amundsen and Makarov basins allow for the determination of the water mass properties of the two components and the construction of a qualitative picture of the circulation both within the Eurasian Basin and towards the Canadian Basin. At the confluence north of the Kara Sea, the Fram Strait branch is displaced from the upper to the lower slope and it forms a sharp front to the Barents Sea water at depths between 100m and greater than 1000m. This front disintegrates downstream along the basin margin and the two components are largely mixed before the boundary current reaches the Lomonosov Ridge. Away from the continental slope, the presence of interleaving structures coherent over wide distances is consistent with low lateral shear. The return flow along the Nansen Gakkel Ridge, if present at all, seems to be slow and the cold water below a deep mixed layer there indicates that the Fram Strait Atlantic water was not covered with a halocline for about a decade. Anomalous water mass properties in the interior of the Eurasian Basin can be attributed to isolated lenses rather than to baroclinic flow cores. Eddies have probably detached from the front at the confluence and migrated into the interior of the basin. One deep (2500m) lens of Canadian Basin water, with an anticyclonic eddy signature, must have spilled through a gap of the Lomonosov Ridge. During ACSYS 96, no clear fronts between Eurasian and Canadian intermediate waters, such as those observed further north in 1991 and 1994, were found at the Siberian side of the Lomonosov Ridge. This indicates that the Eurasian Basin waters enter the Canadian Basin not only along the continental slope but they may also cross the Lomonosov Ridge at other topographic irregularities. A decrease in salinity around 1000 m in depth in the Amundsen Basin probably originates from a larger input of fresh water to the Barents Sea. The inherent density changes may affect the flow towards the Canadian Basin.

Ekwurzel, B, Schlosser P, Mortlock RA, Fairbanks RG, Swift JH.  2001.  River runoff, sea ice meltwater, and Pacific water distribution and mean residence times in the Arctic Ocean. Journal of Geophysical Research-Oceans. 106:9075-9092.   10.1029/1999jc000024   AbstractWebsite

Hydrographic and tracer data collected during ARK IV/3 (FS Polarstern in 1987), ARCTIC91 (IB Oden), and AOS94 (CCGS Louis S. St-Laurent) expeditions reveal the evolution of the near-surface waters in the Arctic Ocean during the late 1980s and early 1990s. Salinity, nutrients, dissolved oxygen, and delta (18)O data are used to quantify the components of Arctic freshwater: river runoff, sea ice meltwater, and Pacific water. The calculated river runoff fractions suggest that in 1994 a large portion of water from the Pechora, Oh, Yenisey, Kotuy, and Lena Rivers did not flow off the shelf closest to their river deltas, but remained on the shelf and traveled via cyclonic circulation into the Laptev and East Siberian Seas. River runoff flowed off the shelf at the Lomonosov Ridge and most left the shelf at the Mendeleyev Ridge. ARCTIC91 and AOS94 Pacific water fraction estimates of Upper Halocline Water, the traditionally defined core of the Pacific water mass, document a decrease in extent compared to historical data. The front between Atlantic water and Pacific water shifted from the Lomonosov Ridge location in 1991 to the Mendeleyev Ridge in 1994. The relative age structure of the upper waters is described by using the (3)H-(3)He age. The mean (3)H-(3)He age measured in the halocline within the salinity surface of 33.1 +/- 0.3 is 4.3 +/- 1.7 years and that for the 34.2 +/- 0.2 salinity surface is 9.6 +/- 4.6 years. Lateral variations in the relative age structure within the halocline and Atlantic water support the well-known cyclonic boundary current circulation.

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.

Macdonald, RW, Carmack EC, McLaughlin FA, Falkner KK, Swift JH.  1999.  Connections among ice, runoff and atmospheric forcing in the Beaufort Gyre. Geophysical Research Letters. 26:2223-2226.   10.1029/1999gl900508   AbstractWebsite

During SHEBA, thin ice and freshening of the Arctic Ocean surface in the Beaufort Sea led to speculation that perennial sea ice was disappearing [McPhee Ei al., 1998]. Since 1987, we have collected salinity, delta(18)O and Ba profiles near the initial SHEBA site and, in 1997, we ran a section out to SHEBA. Resolving fresh water into runoff and ice melt, we found a large background of Mackenzie River water with exceptional amounts in 1997 explaining much of the freshening at SHEBA. Ice melt went through a dramatic 4-6 m jump in the early 1990s coinciding with the atmospheric pressure field and sea-ice circulation becoming more cyclonic. The increase in sea-ice melt appears to be a thermal and mechanical response to a circulation regime shift. Should atmospheric circulation revert to the more anticyclonic mode, ice conditions can also be expected to revert a! though not necessarily to previous conditions.

Swift, JH.  1999.  The oceanography of the Arctic Ocean. Current. 15:28-32. Abstract
Jones, EP, Anderson LG, Swift JH.  1998.  Distribution of Atlantic and Pacific waters in the upper Arctic Ocean: Implications for circulation. Geophysical Research Letters. 25:765-768.   10.1029/98gl00464   AbstractWebsite

The Atlantic and Pacific oceans provide source waters for the Arctic Ocean that can be distinguished by their differing nitrate and phosphate concentration relationships. Using these relationships, we estimate the amount of Atlantic and Pacific waters in the surface layer (top 30 m) of the Arctic Ocean. Atlantic source water is dominant in most of the Eurasian Basin and is present in significant amounts in the Makarov Basin north of the East Siberian Sea. Pacific source water is dominant in most of the Canadian Basin and is present in significant amounts in the Amundsen Basin north of Greenland. We deduce circulation patterns from the distributions of Atlantic and Pacific source waters in the surface layer of the Arctic Ocean and conclude that the flow within the surface layer differs from ice drift along the North American and European boundaries of the Polar Basin.

Carmack, EC, Aagaard K, Swift JH, Perkin RG, McLaughlin FA, Macdonald RW, Jones EP.  1998.  Thermohaline transitions. Physical processes in lakes and oceans. ( Imberger J, Ed.).:179-186., Washington, DC: American Geophysical Union Abstract
Schlosser, P, Kromer B, Ekwurzel B, Bonisch G, McNichol A, Schneider R, vonReden K, Ostlund HG, Swift JH.  1997.  The first trans-Arctic 14C section: comparison of the mean ages of the deep waters in the Eurasian and Canadian basins of the Arctic Ocean. Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms. 123:431-437.   10.1016/s0168-583x(96)00677-5   AbstractWebsite

We present Delta(14)C data collected during three cruises to the Arctic Ocean that took place in the summers of 1987 (POLARSTERN cruise ARK IV/3), 1991 (ARCTIC 91 Expedition), and 1994 (Arctic Ocean Section 94). The cruise tracks of these three expeditions cover all major basins of the Arctic Ocean (Nansen, Amundsen, Makarov and Canada basins), and can be combined to a trans-Arctic section reaching from the Barents Sea slope to the southern Canada Basin just north of Bering Strait. The section is based on 17 stations covering the entire water column (about 250 data points). The combined Delta(14)C data set was produced from a mixture of large volume samples measured by low-level counting and small volume samples measured by Accelerator Mass Spectrometry (AMS). We use the Delta(14)C section, together with previously published Delta(14)C data from single stations located in several basins of the Arctic Ocean, to derive mean ''ages'': (isolation times) of the deep waters in the Arctic Ocean. We estimate these mean ''ages'' to be approximate to 250 years in the bottom waters of the Eurasian Basin and approximate to 450 years in the Canadian Basin Deep Water. A remarkable feature of the Delta(14)C section is the homogeneity in the C-14 distribution observed in the deep Canadian Basin. Within the measurement precision of about +/- 2 parts per thousand (LV) to about +/- 5 parts per thousand (AMS), we cannot detect significant horizontal or vertical Delta(14)C gradients below 2000 m depth between the northern boundary of the Makarov Basin and the southern margin of the Canada Basin. There is no statistically significant difference between samples measured by AMS and by low-level counting.

Zheng, Y, Schlosser P, Swift JH, Jones EP.  1997.  Oxygen utilization rates in the Nansen Basin, Arctic Ocean: implications for new production. Deep-Sea Research Part I-Oceanographic Research Papers. 44:1923-1943.   10.1016/s0967-0637(97)00046-0   AbstractWebsite

In situ consumption of oxygen is balanced by ventilation if the observed distribution of dissolved oxygen below the euphotic zone is in steady state. Apparent oxygen utilization rates (AOURs) can be estimated from the observed oxygen distribution if the waters of the upper layers can be dated. It has been shown previously that tritium/(3)He ages can be used, together with observed oxygen concentrations, to estimate AOURs for waters with ages of several months to several decades. This method is applied to data obtained from the Nansen Basin, Arctic Ocean, during the 1987 cruise of F.S. Polarstern. New production is estimated by depth integration of AOURs calculated for several isopycnals to be 19+/-5g C m(-2) year(-1) for the southern part and 3+/-2 g C m(-2) year(-1) for the northern part of the Nansen Basin section. The results are discussed and compared with previous estimates based on different methods. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.

Carmack, EC, Aagaard K, Swift JH, Macdonald RW, McLaughlin FA, Jones EP, Perkin RG, Smith JN, Ellis KM, Killius LR.  1997.  Changes in temperature and tracer distributions within the Arctic Ocean: Results from the 1994 Arctic Ocean section. Deep-Sea Research Part Ii-Topical Studies in Oceanography. 44:1487-+.   10.1016/s0967-0645(97)00056-8   AbstractWebsite

Major changes in temperature and tracer properties within the Arctic Ocean are evident in a comparison of data obtained during the 1994 Arctic Ocean Section to earlier measurements. (1) Anomalously warm and well-ventilated waters are now found in the Nansen, Amundsen and Makarov basins, with the largest temperature differences, as much as 1 degrees C, in the core of the Atlantic layer (200-400 m). This thermohaline transition appears to follow from two distinct mechanisms: narrow (order 100 km), topographically-steered cyclonic flows that rapidly carry new water around the perimeters of the basins; and multiple intrusions, 40-60 m thick, which extend laterally into the basin interiors. (2) Altered nutrient distributions that within the halocline distinguish water masses of Pacific and Atlantic origins likewise point to a basin-wide redistribution of properties. (3) Distributions of CFCs associated with inflows from adjacent shelf regions and from the Atlantic demonstrate recent ventilation to depths exceeding 1800 m. (4) Concentrations of the pesticide HCH in the surface and halocline layers are supersaturated with respect to present atmospheric concentrations and show that the ice-capped Arctic Ocean is now a source to the global atmosphere of this contaminant. (5) The radionuclide I-129 is now widespread throughout the Arctic Ocean. Although the current level of I-129 level poses no significant radiological threat, its rapid arrival and wide distribution illustrate the speed and extent to which waterborne contaminants are dispersed within the Arctic Ocean on pathways along which other contaminants can travel from western European or Russian sources. (C) 1998 Elsevier Science Ltd. All rights reserved.

Swift, JH, Jones EP, Aagaard K, Carmack EC, Hingston M, Macdonald RW, McLaughlin FA, Perkin RG.  1997.  Waters of the Makarov and Canada basins. Deep-Sea Research Part Ii-Topical Studies in Oceanography. 44:1503-1529.   10.1016/s0967-0645(97)00055-6   AbstractWebsite

Hydrographic measurements from the 1994 Arctic Ocean Section show how the Makarov and Canada basins of the Arctic Ocean are related, and demonstrate their oceanographic connections to the Eurasian Basin. The inflow into the Makarov Basin consists largely of well-ventilated water within a broad band of densities from a boundary how over the Siberian end of the Lomonosov Ridge. The boundary flow contains a significant component of dense shelf water likely originating in the Barents, Kara, and Laptev Seas. Earlier ice camp data show that the Canada Basin is relatively more isolated from this ventilation source. In the Canada Basin shelf sources influenced by Bering Sea water appear to add cold waters with high silicate concentrations to the halocline and deeper. In 1994 the halocline silicate maximum over the central Makarov Basin was absent, evidence of the recent displacement of the upper (S similar to 33.1) halocline water from the Chukchi-East Siberian Sea region by water from the Eurasian Basin. Much of the Makarov Basin water in and below the halocline is in fact from the Eurasian Basin, with admixture of waters from the Canada Basin suggested by their higher silicate concentrations. Mid-depth eddies may transport anomalous properties into the central Arctic and create property gradients or fronts in mid-depth and deep waters. The complex topography of the Mendeleyev Ridge-Chukchi Plateau region also may assist spreading of water from the boundary into the interior. Atlantic layer characteristics in 1994 differed from previous general depictions. In particular the core temperatures at the Chukchi-Mendeleyev boundary were at least 0.2 degrees C warmer on average than indicated in earlier work. The recent warming at intermediate depth has resulted from inflow of Atlantic waters that have been cooled relatively little during their transit of the Norwegian Sea. (C) 1998 Elsevier Science Ltd. All rights reserved.

Dickson, R, Lazier J, Meincke J, Rhines P, Swift J.  1996.  Long-term coordinated changes in the convective activity of the North Atlantic. Progress in Oceanography. 38:241-295.   10.1016/s0079-6611(97)00002-5   AbstractWebsite

The North Atlantic is a peculiarly convective ocean. The convective renewal of intermediate and deep waters in the Labrador Sea and Greenland/Iceland Sea both contribute significantly to the production and export of North Atlantic Deep Water, thus helping to drive the global thermohaline circulation, while the formation and spreading of 18-Degree Water at shallow-to-intermediate depths off the US eastern seaboard is a major element in the circulation and hydrographic character of the west Atlantic. For as long as time-series of adequate precision have been available to us, it has been apparent that the intensity of convection at each of these sites, and the hydrographic character of their products have been subject to major interannual change, as shown by AAGAARD (1968), CLARKE, SWIFT, REID and KOLTERMANN (1990), and MEINCKE, JONSSON and SWIFT (1992) for the Greenland Sea, in the OWS BRAVO record from the Labrador Sea, (egLAZIER, 1980 et seq.), and at the Panulirus / Hydrostation "S" site in the Northern Sargasso off Bermuda (eg JENKINS, 1982, TALLEY and RAYMER, 1982). This paper reviews the recent history of these changes showing that the major convective centres of the Greenland and Labrador Seas are currently at opposite convective extrema in our postwar record, with vertical exchange at the former site limited to 1000 m or so, but with Labrador Sea convection reaching deeper than previously observed, to over 2300 m. As a result, the deep water of the Greenland Sea has become progressively warmer and more saline since the early '70s as a result of increased horizontal exchange with the Arctic Ocean through Fram Strait, while the Labrador Sea Water has become progressively colder and fresher over the same period through increased vertical exchange; most recently, convection has become deep enough there to reach into the more saline NADW which underlies it, so that cooler, but now saltier and denser LSW has resulted. The horizontal spreading of these changing watermasses in the northern gyre is described from the hydrographic record. The theory is advanced that the scales of atmospheric forcing have imposed a degree of synchrony on convective behaviour at all three sites over the present century, with ventilation at the Sargasso and Greenland Sea sites undergoing a parallel multi-decadal evolution to reach a long term maximum in the 1960s, driven by the twin cells of the North Atlantic Oscillation (NAO). During the NAO minimum of the 1960s, with an extreme Greenland ridge feeding record amounts of fresh water into the northern gyre in the form of the Great Salinity Anomaly, and its partner cell over the Southeast USA causing a southwestward retraction of storm activity (DICKSON and NAMIAS, 1976), the surface freshening and postwar minimum in storm activity in the intervening area of the Labrador Sea also brought a progressive reduction, and ultimately a cessation, of wintertime convection there during the 1960s. In other words, the evolution of winter convective activity during the century was in phase but of different sign at the three sites. In these events, we see strong evidence of a direct impact of the shifting atmospheric circulation on the ocean; while this certainly does not rule out either feedbacks from anomalous ice and SST conditions on the atmosphere, or autonomous oscillations of the ocean's overturning circulation, it does tend to minimise them. Crown copyright (C) 1997 Published by Elsevier Science Ltd

Aagaard, K, Barrie L, Carmack E, Garrity C, Jones EP, Lubin D, Macdonald RW, Swift JH, Tucker W, Wheeler PA, Whritner R.  1996.  U.S., Canadian researchers explore Arctic Ocean. EOS, Transactions American Geophysical Union. 77:209,213.   10.1029/96EO00141   Abstract

During July–September 1994, two Canadian and U.S. ice breakers crossed the Arctic Ocean (Figure 1) to investigate the biological, chemical, and physical systems that define the role of the Arctic in global change. The results are changing our perceptions of the Arctic Ocean as a static environment with low biological productivity to a dynamic and productive system. The experiment was called the Arctic Ocean Section (AOS) and the ships were the Canadian Coast Guard ship Louis S. St.-Laurent and the U.S. Coast Guard cutter Polar Sea.

Swift, JH.  1995.  A few notes on a recent deep-water freshening. Natural climate variability on decade-to-century time scales. ( Council N, Ed.).:290-294., Washington, D.C.: National Academy Press Abstract
Swift, JH.  1995.  Comparing WOCE and historical temperatures in the deep southeast Pacific. International WOCE Newsletter, WOCE Int'l Project Office. 18:15-17. AbstractWebsite
Schlosser, P, Swift JH, Lewis D, Pfirman SL.  1995.  The role of the large-scale Arctic Ocean circulation in the transport of contaminants. Deep-Sea Research Part Ii-Topical Studies in Oceanography. 42:1341-1367.   10.1016/0967-0645(95)00045-3   AbstractWebsite

The key features of the large-scale circulation of the Arctic Ocean are reviewed based on distributions of hydrographic parameters and natural and anthropogenic trace substances. Salinity and mass balances, as well as a combination of the tracers tritium and delta(18)O, suggest a mean residence time of the shelf waters in the Siberian seas of about 3 years. Potential pathways of pollutants released to the Siberian shelf seas from the dumpsites or from river runoff are inferred from the distributions of delta(18)O and salinity. Transit times needed for dissolved contaminants to cross the central Arctic basins (several years to one or two decades in near-surface waters) and mean residence times of contaminants in the intermediate (several decades) and deep waters (several centuries) are estimated from the distribution of transient tracers (tritium and its radioactive decay product, He-3) and ''steady-state'' tracers (C-14 and Ar-39).

Anderson, LG, Bjork G, Holby O, Jones EP, Kattner G, Koltermann KP, Liljeblad B, Lindegren R, Rudels B, Swift J.  1994.  Water masses and circulation in the Eurasian Basin: Results from the Oden 91 expedition. Journal of Geophysical Research-Oceans. 99:3273-3283.   10.1029/93jc02977   AbstractWebsite

The Oden 91 North Pole expedition obtained oceanographic measurements on four sections in the Nansen and Amundsen basins of the Eurasian Basin and in the Makarov Basin of the Canadian Basin, thereby proving the feasibility of carrying out a typical oceanographic program using an icebreaker in the Arctic Ocean. The data show greater spatial variability in water structure and circulation than was apparent from previous data. The results show that a clear front exists between the Eurasian and Canadian basins such that upper halocline water in the Canadian Basin is almost absent from the Eurasian Basin. The lower halocline water produced in the Barents-Kara Sea region permeates much of the Eurasian Basin and flows along the continental slope into the Canadian Basin. The deeper circulation is strongly influenced by topography. Three return flows of the Atlantic layer are identified, one over the Nansen-Gakkel Ridge, one over the Lomonosov Ridge, and a third flowing from the Canadian Basin. The slight differences observed in salinity and temperature characteristics of the deeper waters of the Nansen and Amundsen basins do not lead to an obvious explanation of their origin or flow pattern.

Meincke, J, Jonsson S, Swift JH.  1992.  Variability of convective conditions in the Greenland Sea. Hydrobiological variability in the ICES area, 1980-1989. 195( Dickson RR, Maelkki P, Radach G, Saetre R, Sissenwine MP, Meincke J, Eds.).:32-39., Copenhagen (Denmark): ICES Abstract

Recent observations and data compilations show decadal and interannual variations in the depth of wintertime convection in the Greenland Sea. In a qualitative study the fluctuations are related to changes in wind and thermohaline forcing. Changes in both wind-stress curl and sea-ice cover concur with the results from hydrographic observations indicating that no renewal of deep water has taken place during the 1980s.

Aagaard, K, Fahrbach E, Meincke J, Swift JH.  1991.  Saline outflow from the Arctic Ocean: Its contribution to the deep waters of the Greenland, Norwegian, and Iceland seas. Journal of Geophysical Research-Oceans. 96:20433-20441.   10.1029/91jc02013   AbstractWebsite

Since 1985 various investigators have proposed that Norwegian Sea deep water (NSDW) is formed by mixing of warm and saline deep water from the Arctic Ocean with the much colder and fresher deep water formed by convection in the Greenland Sea (GSDW). We here report on new observations which suggest significant modification and expansion of this conceptual model. We find that saline outflows from the Arctic Ocean result in several distinct intermediate and deep salinity maxima within the Greenland Sea; the southward transport of the two most saline modes is probably near 2 Sv. Mixing of GSDW and the main outflow core found over the Greenland slope, derived from about 1700 m in the Arctic Ocean, cannot by itself account for the properties of NSDW. Instead, the formation of NSDW must at least in part involve a source which in the Arctic Ocean is found below 2000 m. The mixing of various saline outflows is diapycnal. While significant NSDW production appears to occur in northern Fram Strait, large amounts of saline Arctic Ocean outflow also traverse the western Greenland Sea without mixing and enter the Iceland Sea. During the past decade, deep convection in the Greenland Sea has been greatly reduced, while deep outflow from the Arctic Ocean appears to have continued, resulting in a markedly warmer, slightly more saline, and less dense deep regime in the Greenland Sea.

Hamann, IM, Swift JH.  1991.  A consistent inventory of water mass factors in the intermediate and deep Pacific Ocean derived from conservative tracers. Deep-Sea Research Part a-Oceanographic Research Papers. 38:S129-S169.   10.1016/S0198-0149(12)80008-2   AbstractWebsite

Estimates of the characteristics and proportional importance of water mass factors are determined by exploratory multivariate Q-mode factor analysis (QMFA) of Pacific Ocean hydrographic data from the region north of 30-degrees-S. The inter-tracer ratios between potential temperature, salinity, the calculated parameters "NO" and "PO" and silicate are used to establish a matrix of similarity coefficients between all station locations. Its rotated eigenvectors ("factors") are viewed as distinct water types of the system. On individual key density surfaces QMFA shows that the spatial distribution of relative contributions from the primary factors can be linked to known or suspected water types and their subsequent spreading. The minor factors reflect smaller perturbations of the dominating ratios. Another QMFA was done in three dimensions by combining all density layers to determine factors derived from diapycnal as well as isopycnal property gradients. Two primary factors represent the opposing vertical temperature and salinity-nutrients gradient: "a deep water melange", which concentrates in the Northeast Pacific (maximum where sigma-1 greater-than-or-equal-to 31.93), and a "subtropical thermocline" factor (maximum on sigma-theta = 25.80) centered in the subtropical gyres. The spatially uneven decrease of relative contribution from a "shallow" factor as one moves down from the upper to the lower thermocline suggests areas where the exchange with the "deeper" factor may be enhanced.

Roemmich, D, McCallister T, Swift J.  1991.  A transpacific hydrographic section along latitude 24°N: the distribution of properties in the subtropical gyre. Deep-Sea Research Part a-Oceanographic Research Papers. 38:S1-S20.   10.1016/S0198-0149(12)80002-1   AbstractWebsite

An intensively sampled transpacific hydrographic section along 24-degrees-N was completed in the spring of 1985. The data are described here in terms of the spatial distribution of properties, the distribution along isopycnal surfaces, and, where possible, the relationship of these distributions to the large-scale circulation of the Pacific Ocean. Near-surface waters of subtropical origin display a salinity maximum in mid-ocean, with lower salinity to the west due to greater rainfall and lower salinity in the east due to advection of water from the north. In the next layers down, containing waters of subpolar origin, the low salinity and high dissolved oxygen concentrations of those waters are most pronounced in the eastern ocean where the subpolar water is swept clockwise into the subtropical gyre. Differences between patterns of dissolved oxygen concentration and salinity indicate that both horizontal advection and upwelling contribute to observed distributions near the eastern boundary and that the two tracers contain independent information. In the upper kilometer, the eastern Pacific is richer in tracer signals and has steeper property gradients than the west. The deep Pacific has long been recognized to be the most uniform of the oceans. Although property gradients are small, they are significant, and it is found that on all isopycnal surfaces below the upper kilometer salinity increases and dissolved oxygen concentration decreases towards the east on basin-wide scales. These zonal gradients are weakest in the abyss, where there is a substantial net input of southern water, and strongest at mid-depth. Vertical diffusion is the likely cause of the uniformity in this pattern over so much of the deep North Pacific, with oxygen consumption in waters of greater age in the east also being a plausible contributor. With a highly sampled data set such as the 24-degrees-N transpacific section it is appropriate to ask how many stations are required to define property distributions and to estimate large-scale circulation and transport. Estimation of geostrophic transport requires high spatial resolution to detect flow near sloping topography at all depths. A 50% decimation of the 24-degrees-N station pattern yields a severe degradation in the estimation of transport.