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2011
Hartin, CA, Fine RA, Sloyan BM, Talley LD, Chereskin TK, Happell J.  2011.  Formation rates of Subantarctic mode water and Antarctic intermediate water within the South Pacific. Deep-Sea Research Part I-Oceanographic Research Papers. 58:524-534.   10.1016/j.dsr.2011.02.010   AbstractWebsite

The formation of Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW) significantly contributes to the total uptake and storage of anthropogenic gases, such as CO(2) and chlorofluorocarbons (CFCs), within the world's oceans. SAMW and AAIW formation rates in the South Pacific are quantified based on CFC-12 inventories using hydrographic data from WOCE. CLIVAR, and data collected in the austral winter of 2005. This study documents the first wintertime observations of CFC-11 and CFC-12 saturations with respect to the 2005 atmosphere in the formation region of the southeast Pacific for SAMW and AAIW. SAMW is 94% and 95% saturated for CFC-11 and CFC-12, respectively, and AAIW is 60% saturated for both CFC-11 and CFC-12. SAMW is defined from the Subantarctic Front to the equator between potential densities 26.80-27.06 kg m(-3), and AAIW is defined from the Polar Front to 20 degrees N between potential densities 27.06-27.40 kg m(-3). CFC-12 inventories are 16.0 x 10(6) moles for SAMW and 8.7 x 10(6) moles for AAIW, corresponding to formation rates of 7.3 +/- 2.1 Sv for SAMW and 5.8 +/- 1.7 Sv for AAIW circulating within the South Pacific. Inter-ocean transports of SAMW from the South Pacific to the South Atlantic are estimated to be 4.4 +/- 0.6 Sv. Thus, the total formation of SAMW in the South Pacific is approximately 11.7 +/- 2.2 Sv. These formation rates represent the average formation rates over the major period of CFC input, from 1970 to 2005. The CFC-12 inventory maps provide direct evidence for two areas of formation of SAMW, one in the southeast Pacific and one in the central Pacific. Furthermore, eddies in the central Pacific containing high CFC concentrations may contribute to SAMW and to a lesser extent AAIW formation. These CFC-derived rates provide a baseline with which to compare past and future formation rates of SAMW and AAIW. (C) 2011 Elsevier Ltd. All rights reserved.

National Research Council(U.S.). Committee on Future Science Opportunities in Antarctica and the Southern Ocean., Board. NRCPR(US).  2011.  Future science opportunities in Antarctica and the Southern Ocean. :1onlineresource(xiv,195pages)., Washington, D.C.: National Academies Press AbstractWebsite

"Antarctica and the surrounding Southern Ocean remains one of the world's last frontiers. Covering nearly 14 million km p2 s (an area approximately 1.4 times the size of the United States), Antarctica is the coldest, driest, highest, and windiest continent on Earth. While it is challenging to live and work in this extreme environment, this region offers many opportunities for scientific research. Ever since the first humans set foot on Antarctica a little more than a century ago, the discoveries made there have advanced our scientific knowledge of the region, the world, and the Universe--but there is still much more to learn. However, conducting scientific research in the harsh environmental conditions of Antarctica is profoundly challenging. Substantial resources are needed to establish and maintain the infrastructure needed to provide heat, light, transportation, and drinking water, while at the same time minimizing pollution of the environment and ensuring the safety of researchers. Future Science Opportunities in Antarctica and the Southern Ocean suggests actions for the United States to achieve success for the next generation of Antarctic and Southern Ocean science. The report highlights important areas of research by encapsulating each into a single, overarching question. The questions fall into two broad themes: (1) those related to global change, and (2) those related to fundamental discoveries. In addition, the report identified key science questions that will drive research in Antarctica and the Southern Ocean in coming decades, and highlighted opportunities to be leveraged to sustain and improve the U.S. research efforts in the region."--Publisher's description.

2008
Talley, LD.  2008.  Freshwater transport estimates and the global overturning circulation: Shallow, deep and throughflow components. Progress in Oceanography. 78:257-303.   10.1016/j.pocean.2008.05.001   AbstractWebsite

Meridional ocean freshwater transports and convergences are calculated from absolute geostrophic velocities and Ekman transports. The freshwater transports are analyzed in terms of mass-balanced contributions from the shallow, ventilated circulation of the subtropical gyres, intermediate and deep water overturns, and Indonesian Throughflow and Bering Strait components. The following are the major conclusions: 1. Excess freshwater in high latitudes must be transported to the evaporative lower latitudes, as is well known. The calculations here show that the northern hemisphere transports most of its high latitude freshwater equatorward through North Atlantic Deep Water (NADW) formation (as in [Rahmstorf, S., 1996. On the freshwater forcing and transport of the Atlantic thermohaline circulation. Climate Dynamics 12, 799-811]), in which saline subtropical surface waters absorb the freshened Arctic and subpolar North Atlantic surface waters (0.45 +/- 0.15 Sv for a 15 Sv overturn), plus a small contribution from the high latitude North Pacific through Bering Strait (0.06 +/- 0.02 Sv). In the North Pacific, formation of 2.4 Sv of North Pacific Intermediate Water (NPIW) transports 0.07 +/- 0.02 Sv of freshwater equatorward. In complete contrast, almost all of the 0.61 +/- 0.13 Sv of freshwater gained in the Southern Ocean is transported equatorward in the upper ocean, in roughly equal magnitudes of about 0.2 Sv each in the three subtropical gyres, with a smaller contribution of <0. 1 Sv from the Indonesian Throughflow loop through the Southern Ocean. The large Southern Ocean deep water formation (27 Sv) exports almost no freshwater (0.01 +/- 0.03 Sv) or actually imports freshwater if deep overturns in each ocean are considered separately (-0.06 +/- 0.04 Sv). This northern-southern hemisphere asymmetry is likely a consequence of the "Drake Passage" effect, which limits the southward transport of warm, saline surface waters into the Antarctic [Toggweiler, J.R., Samuels, B., 1995a. Effect of Drake Passage on the global thermohaline circulation. Deep-Sea Research 1 42(4), 477-500]. The salinity contrast between the deep Atlantic, Pacific and Indian source waters and the denser new Antarctic waters is limited by their small temperature contrast, resulting in small freshwater transports. No such constraint applies to NADW formation, which draws on warm, saline subtropical surface waters. 2. The Atlantic/Arctic and Indian Oceans are net evaporative basins, hence import freshwater via ocean circulation. For the Atlantic/Arctic north of 32 degrees S, freshwater import (0.28 +/- 0.04 Sv) comes from the Pacific through Bering Strait (0.06 0.02 Sv), from the Southern Ocean via the shallow gyre circulation (0.20 +/- 0.02 Sv), and from three nearly canceling conversions to the NADW layer (0.02 0.02 Sv): from saline Benguela Current surface water (-0.05 +/- 0.01 Sv), fresh AAIW (0.06 0.01 Sv) and fresh AABW/LCDW (0.01 0.01 Sv). Thus, the NADW freshwater balance is nearly closed within the Atlantic/Arctic Ocean and the freshwater transport associated with export of NADW to the Southern Ocean is only a small component of the Atlantic freshwater budget. For the Indian Ocean north of 32 degrees S, import of the required 0.37 +/- 0.10 Sv of freshwater comes from the Pacific through the Indonesian Throughflow (0.23 +/- 0.05 Sv) and the Southern Ocean via the shallow gyre circulation (0.18 +/- 0.02 Sv), with a small export southward due to freshening of bottom waters as they upwell into deep and intermediate waters (-0.04 +/- 0.03 Sv). The Pacific north of 28 degrees S is essentially neutral with respect to freshwater, -0.04 +/- 0.09 Sv. This is the nearly balancing sum of export to the Atlantic through Bering Strait (-0.07 +/- 0.02 Sv), export to the Indian through the Indonesian Throughflow (-0.17 +/- 0.05 Sv), a negligible export due to freshening of upwelled bottom waters (-0.03 +/- 0.03 Sv), and import of 0.23 +/- 0.04 Sv from the Southern Ocean via the shallow gyre circulation. 3. Bering Strait's small freshwater transport of <0.1 Sv helps maintains the Atlantic-Pacific salinity difference. However, proportionally large variations in the small Bering Strait transport would only marginally impact NADW salinity, whose freshening relative to saline surface water is mainly due to air-sea/runoff fluxes in the subpolar North Atlantic and Arctic. In contrast, in the Pacific, because the total overturning rate is much smaller than in the Atlantic, Bering Strait freshwater export has proportionally much greater impact on North Pacific salinity balances, including NPIW salinity. (C) 2008 Elsevier Ltd. All rights reserved.