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Talley, LD.  2013.  Closure of the Global Overturning Circulation Through the Indian, Pacific, and Southern Oceans: Schematics and Transports. Oceanography. 26:80-97. AbstractWebsite

The overturning pathways for the surface-ventilated North Atlantic Deep Water (NADW) and Antarctic Bottom Water (AABW) and the diffusively formed Indian Deep Water (IDW) and Pacific Deep Water (PDW) are intertwined. The global overturning circulation (GOC) includes both large wind-driven upwelling in the Southern Ocean and important internal diapycnal transformation in the deep Indian and Pacific Oceans. All three northern-source Deep Waters (NADW, IDW, PDW) move southward and upwell in the Southern Ocean. AABW is produced from the denser, salty NADW and a portion of the lighter, low oxygen IDW/PDW that upwells above and north of NADW. The remaining upwelled IDW/PDW stays near the surface, moving into the subtropical thermoclines, and ultimately sources about one-third of the NADW. Another third of the NADW comes from AABW upwelling in the Atlantic. The remaining third comes from AABW upwelling to the thermocline in the Indian-Pacific. Atlantic cooling associated with NADW formation (0.3 PW north of 32 degrees S; 1 PW = 1015 W) and Southern Ocean cooling associated with AABW formation (0.4 PW south of 32 degrees S) are balanced mostly by 0.6 PW of deep diffusive heating in the Indian and Pacific Oceans; only 0.1 PW is gained at the surface in the Southern Ocean. Thus, while an adiabatic model of NADW global overturning driven by winds in the Southern Ocean, with buoyancy added only at the surface in the Southern Ocean, is a useful dynamical idealization, the associated heat changes require full participation of the diffusive Indian and Pacific Oceans, with a basin-averaged diffusivity on the order of the Munk value of 10(-4) m(2) s(-1).

Talley, LD.  1988.  Potential Vorticity Distribution in the North Pacific. Journal of Physical Oceanography. 18:89-106.   10.1175/1520-0485(1988)018<0089:pvditn>2.0.co;2   AbstractWebsite

Vertical sections and maps of potential vorticity ρ−1f∂ρ/∂z for the North Pacific are presented. On shallow isopycnals, high potential vorticity is found in the tropics, subpolar gyre, and along the eastern boundary of the subtropical gyre, all associated with Ekman upwelling. Low potential vorticity is found in the western subtropical gyre (subtropical mode water), in a separate patch near the sea surface in the eastern subtropical gyre and extending around the gyre, and near sea-surface outcrops in the subpolar gyre; the last is analogous to the subpolar mode water of the North Atlantic and Southern Ocean.Meridional gradients of potential vorticity are high between the subtropical and subpolar gyres at densities which outcrop only in the subpolar gyre; lateral gradients of potential vorticity are low in large regions of the subtropical gyre on these isopycnals. On slightly denser isopycnals which do not outcrop in the North Pacific, there are large regions of low potential vorticity gradients which cross the subtropical-subpolar gyre boundary. These regions decrease in area with depth and vanish between 2500 and 3000 meters. Regions of low lateral gradients of potential vorticity are surrounded by and overlie regions where the meridional gradient of potential vorticity is approximately β. In the abyssal waters, below 3500 meters, meridional potential vorticity gradients again decrease, perhaps associated with slow geothermal heating. The depth and shape of the region wheel potential vorticity is relatively uniform or possesses closed contours is noted and related to theories of wind-driven circulation.

Talley, LD, Fryer G, Lumpkin R.  1998.  Physical oceanography of the tropical Pacific. Geography of the Pacific Islands. ( Rapaport M, Ed.).:19-32., Honolulu: Bess Press Abstract
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Talley, LD, Rosso I, Kamenkovich I, Mazloff MR, Wang J, Boss E, Gray AR, Johnson KS, Key R, Riser SC, Williams NL, Sarmiento JL.  2018.  Southern Ocean biogeochemical float deployment strategy, with example from the Greenwich Meridian line (GO-SHIP A12). Journal of Geophysical Research: Oceans.   10.1029/2018JC014059   Abstract

Biogeochemical Argo floats, profiling to 2000 m depth, are being deployed throughout the Southern Ocean by the Southern Ocean Carbon and Climate Observations and Modeling program (SOCCOM). The goal is 200 floats by 2020, to provide the first full set of annual cycles of carbon, oxygen, nitrate and optical properties across multiple oceanographic regimes. Building from no prior coverage to a sparse array, deployments are based on prior knowledge of water mass properties, mean frontal locations, mean circulation and eddy variability, winds, air-sea heat/freshwater/carbon exchange, prior Argo trajectories, and float simulations in the Southern Ocean State Estimate (SOSE) and Hybrid Coordinate Ocean Model (HYCOM). Twelve floats deployed from the 2014-2015 Polarstern cruise from South Africa to Antarctica are used as a test case to evaluate the deployment strategy adopted for SOCCOM's 20 deployment cruises and 126 floats to date. After several years, these floats continue to represent the deployment zones targeted in advance: (1) Weddell Gyre sea ice zone, including the Antarctic Slope Front, Maud Rise, and the open gyre; (2) Antarctic Circumpolar Current (ACC) including the topographically-steered Southern zone ‘chimney' where upwelling carbon/nutrient-rich deep waters produce surprisingly large carbon dioxide outgassing; (3) Subantarctic and Subtropical zones between the ACC and Africa; and (4) Cape Basin. Argo floats and eddy-resolving HYCOM simulations were the best predictors of individual SOCCOM float pathways, with uncertainty after 2 years on the order of 1000 km in the sea ice zone and more than double that in and north of the ACC.

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.

Talley, LD.  1985.  Ventilation of the Sub-Tropical North Pacific - the Shallow Salinity Minimum. Journal of Physical Oceanography. 15:633-649.   10.1175/1520-0485(1985)015<0633:votsnp>2.0.co;2   AbstractWebsite

The shallow salinity minimum of the subtropical North Pacific is shown to be a feature of the ventilated, wind-driven circulation. Subduction of low salinity surface water in the northeastern subtropical gyre beneath higher salinity water to the south causes the salinity minimum. Variation of salinity along surface isopycnals causes variations in density and salinity at the minimum.A model of ventilated flow is used to demonstrate how the shallow salinity minimum can arise. The model is modified to account for nonzonal, realistic winds; it is also extended to examine the three-dimensional structure of the western shadow zone. The boundary between the subtropical and subpolar gyres is given by the zero of the zonal integral of Ekman pumping. The western shadow zone fills the subtropical gyre at the base of the ventilated layers and decreases in extent with decreasing density. For parameters appropriate to the North Pacific, the eastern shadow zone is of very limited extent.Observations of salinity and potential vorticity within and below the ventilated layer bear out model predictions of the extent of the western shadow zone.

Talley, LD.  2003.  Shallow, intermediate, and deep overturning components of the global heat budget. Journal of Physical Oceanography. 33:530-560.   10.1175/1520-0485(2003)033<0530:siadoc>2.0.co;2   AbstractWebsite

The ocean's overturning circulation and associated heat transport are divided into contributions based on water mass ventilation from 1) shallow overturning within the wind-driven subtropical gyres to the base of the thermocline, 2) overturning into the intermediate depth layer (500-2000 m) in the North Atlantic and North Pacific, and 3) overturning into the deep layers in the North Atlantic (Nordic Seas overflows) and around Antarctica. The contribution to South Pacific and Indian heat transport from the Indonesian Throughflow is separated from that of the subtropical gyres and is small. A shallow overturning heat transport of 0.6 PW dominates the 0.8-PW total heat transport at 24degreesN in the North Pacific but carries only 0.1-0.4 PW of the 1.3-PW total in the North Atlantic at 24degreesN. Shallow overturning heat transports in the Southern Hemisphere are also poleward: -0.2 to -0.3 PW southward across 30degreesS in each of the Pacific and Indian Oceans but only -0.1 PW in the South Atlantic. Intermediate water formation of 2 and 7 Sv (1 Sv = 10(6) m(3) s(-1)) carries 0.1 and 0.4 PW in the North Pacific and Atlantic, respectively, while North Atlantic Deep Water formation of 19 Sv carries 0.6 PW. Because of the small temperature differences between Northern Hemisphere deep waters that feed the colder Antarctic Bottom Water (Lower Circumpolar Deep Water), the formation of 22 Sv of dense Antarctic waters is associated with a heat transport of only -0.14 PW across 30degreesS (all oceans combined). Upwelling of Circumpolar Deep Water north of 30degreesS in the Indian (14 Sv) and South Pacific (14 Sv) carries -0.2 PW in each ocean.

Talley, LD.  2013.  Hydrographic Atlas of the World Ocean Circulation Experiment (WOCE). Volume 4: Indian Ocean. ( and M. Sparrow CPJ, Ed.)., Southampton, U.K.: International WOCE Project Office
Talley, LD, Min DH, Lobanov VB, Luchin VA, Ponomarev VI, Salyuk AN, Shcherbina AY, Tishchenko PY, Zhabin I.  2006.  Japan/East Sea water masses and their relation to the sea's circulation. Oceanography. 19:32-49.   10.5670/oceanog.2006.42   Abstract

The Japan/East Sea is a major anomaly in the ventilation and overturn picture of the Pacific Ocean. The North Pacific is well known to be nearly unventilated at intermediate and abyssal depths, reflected in low oxygen concentration at 1000 m (Figure 1). (High oxygen indicates newer water in more recent contact with the atmosphere. Oxygen declines as water "ages" after it leaves the sea surface mainly because of bacterial respiration.) Even the small production of North Pacific Intermediate Water in the Okhotsk Sea (Talley, 1991; Shcherbina et al., 2003) and the tiny amount of new bottom water encountered in the deep Bering Sea (Warner and Roden, 1995) have no obvious impact on the overall oxygen distribution at 1000 m and below, down to 3500 m, which is the approximate maximum depth of the Bering, Okhotsk, and Japan/East Seas.

Talley, LD.  1983.  Radiating Barotropic Instability. Journal of Physical Oceanography. 13:972-987.   10.1175/1520-0485(1983)013<0972:rbi>2.0.co;2   AbstractWebsite

The linear stability of zonal, parallel shear flow on a beta-plane is discussed. While the localized shear region supports unstable waves, the far-field can support Rossby waves because of the ambient potential-vorticity gradient. An infinite zonal flow with a continuous cross-stream velocity gradient is approximated with segments of uniform flow, joined together by segments of uniform potential vorticity. This simplification allows an exact dispersion relation to be found. There are two classes of linearly unstable solutions. One type is trapped to the source of energy and has large growth rates. The second type is weaker instabilities which excite Rossby waves in the far-field: the influence of these weaker instabilities extends far beyond that of the most unstable waves.

Talley, LD, Stammer D, Fukumori I.  2001.  The WOCE Synthesis. Ocean circulation and climate : observing and modelling the global ocean. ( Siedler G, Church J, Gould WJ, Eds.).:525-546., San Diego, Calif. London: Academic Abstract
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Talley, LD.  1996.  North Atlantic circulation and variability, reviewed for the CNLS conference. Physica D. 98:625-646.   10.1016/0167-2789(96)00123-6   AbstractWebsite

The circulation and water mass structure of the North Atlantic are reviewed, with emphasis on the large-scale overturning cell which produces North Atlantic Deep Water (NADW). Properties and transports for its major components (Nordic Seas Overflow Water, Labrador Sea Water, Mediterranean Water, Antarctic Intermediate Water and Antarctic Bottom Water) are reviewed. The transport estimates and properties of NADW coupled with the observed meridional heat transport in the Atlantic limit the temperature of northward flow which replenishes the NADW to the range 11-15 degrees C. The high salinity of the North Atlantic compared with other ocean basins is important for its production of intermediate and deep waters; about one third of its higher evaporation compared with the North Pacific is due to the Mediterranean. The evaporation/precipitation balance for the North Atlantic is similar to the Indian and South Atlantic Oceans; the difference between the North and South Atlantic may be that high evaporation in the North Atlantic affects much greater depths through Mediterranean Water production. Also described briefly is variability of water properties in the upper layers of the subtropical/subpolar North Atlantic, as linked to the North Atlantic Oscillation. The oceanographic time series at Bermuda is then used to show decadal variations in the properties of the Subtropical Mode Water, a thick layer which lies in the upper 500 m. Salinity of this layer and at the sea surface increases during periods when the North Atlantic westerlies weaken between Iceland and the Azores and shift southwestward. (The North Atlantic Oscillation index is low during these periods). Temperature at the surface and in this layer are slightly negatively correlated with salinity, decreasing when salinity increases. It is hypothesized that the salinity increases result from incursion of saline water from the eastern subtropical gyre forced by the southward migration of the westerlies, and that the small temperature decreases are due to increased convection in the Sargasso Sea, also resulting from the southward shift of the westerlies.

Talley, LD, Fryer G, Lumpkin R.  2013.  Oceanography. The Pacific Islands: Environment and Society. ( Rapaport M, Ed.)., Honolulu: University of Hawai'i Press
Talley, LD.  1991.  An Okhotsk Sea-Water Anomaly - Implications for Ventilation in the North Pacific. Deep-Sea Research Part a-Oceanographic Research Papers. 38:S171-S190.   10.1016/S0198-0149(12)80009-4   AbstractWebsite

An unusually cold, fresh and oxygenated layer of water centered at a pressure of 800 dbar and sigma-theta of 27.4 was found at a CTD station in the western Pacific at 43-degrees-5'N, 153-degrees-20'E in August 1985. The anomaly was part of a larger pattern of less dramatic but nevertheless higher variance at densities up to 27.6-sigma-theta in the mixed water region of the Oyashio and Kuroshio, south of the Bussol' Strait, which connects the Sea of Okhotsk and the open North Pacific. Isopycnal maps indicate that the source of the anomaly, which was embedded in a cyclonic flow, was the Okhotsk Sea. Surface properties in the Okhotsk Sea, based on all available NODC observations, and isopycnal maps indicate that the layer probably did not originate at the sea surface in open water. Instead, the principal modifying influences at densities of 26.8-27.6-sigma-theta in the North Pacific are sea-ice formation and vertical mixing, the latter primarily in the Kuril Straits. A simple calculation shows that most of the low salinity influence at these densities in the North Pacific can originate in the Okhotsk Sea and that vertical mixing in the open North Pacific may be much less important than previously thought.

Talley, LD, Tishchenko P, Luchin V, Nedashkovskiy A, Sagalaev S, Kang DJ, Warner M, Min DH.  2004.  Atlas of Japan (East) Sea hydrographic properties in summer, 1999. Progress in Oceanography. 61:277-348.   10.1016/j.pocean.2004.06.011   AbstractWebsite

Hydrographic properties from CTD and discrete bottle sample profiles covering the Japan (East) Sea in summer, 1999, are presented in vertical sections, maps at standard depths, maps on isopycnal surfaces, and as property-property distributions. This data set covers most of the Sea with the exception of the western boundary region and northern Tatar Strait, and includes nutrients, pH, alkalinity, and chlorofluorocarbons, as well as the usual temperature, salinity, and oxygen observations. (C) 2004 Elsevier Ltd. All rights reserved.

Talley, LD, Rosso I, Kamenkovich I, Mazloff MR, Wang J, Boss E, Gray AR, Johnson KS, Key RM, Riser SC, Williams NL, Sarmiento JL.  2019.  Southern Ocean biogeochemical float deployment strategy, with example from the Greenwich meridian line (GO-SHIP A12). Journal of Geophysical Research-Oceans. 124:403-431.   10.1029/2018jc014059   AbstractWebsite

Biogeochemical Argo floats, profiling to 2,000-m depth, are being deployed throughout the Southern Ocean by the Southern Ocean Carbon and Climate Observations and Modeling program (SOCCOM). The goal is 200 floats by 2020, to provide the first full set of annual cycles of carbon, oxygen, nitrate, and optical properties across multiple oceanographic regimes. Building from no prior coverage to a sparse array, deployments are based on prior knowledge of water mass properties, mean frontal locations, mean circulation and eddy variability, winds, air-sea heat/freshwater/carbon exchange, prior Argo trajectories, and float simulations in the Southern Ocean State Estimate and Hybrid Coordinate Ocean Model (HYCOM). Twelve floats deployed from the 2014-2015 Polarstern cruise from South Africa to Antarctica are used as a test case to evaluate the deployment strategy adopted for SOCCOM's 20 deployment cruises and 126 floats to date. After several years, these floats continue to represent the deployment zones targeted in advance: (1) Weddell Gyre sea ice zone, observing the Antarctic Slope Front, and a decadally-rare polynya over Maud Rise; (2) Antarctic Circumpolar Current (ACC) including the topographically steered Southern Zone chimney where upwelling carbon/nutrient-rich deep waters produce surprisingly large carbon dioxide outgassing; (3) Subantarctic and Subtropical zones between the ACC and Africa; and (4) Cape Basin. Argo floats and eddy-resolving HYCOM simulations were the best predictors of individual SOCCOM float pathways, with uncertainty after 2years of order 1,000km in the sea ice zone and more than double that in and north of the ACC.

Talley, L, Fine R, Lumpkin R, Maximenko N, Morrow R.  2010.  Surface Ventilation and Circulation. Proceedings of OceanObs’09: Sustained Ocean Observations and Information for Society. 1( Hall J, Harrison DE, Stammer D, Eds.).   10.5270/OceanObs09.pp.38   Abstract
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Tamsitt, V, Drake HF, Morrison AK, Talley LD, Dufour CO, Gray AR, Griffies SM, Mazloff MR, Sarmiento JL, Wang J, Weijer W.  2017.  Spiraling pathways of global deep waters to the surface of the Southern Ocean. Nature Communications. 8:172.   10.1038/s41467-017-00197-0   Abstract

Upwelling of global deep waters to the sea surface in the Southern Ocean closes the global overturning circulation and is fundamentally important for oceanic uptake of carbon and heat, nutrient resupply for sustaining oceanic biological production, and the melt rate of ice shelves. However, the exact pathways and role of topography in Southern Ocean upwelling remain largely unknown. Here we show detailed upwelling pathways in three dimensions, using hydrographic observations and particle tracking in high-resolution models. The analysis reveals that the northern-sourced deep waters enter the Antarctic Circumpolar Current via southward flow along the boundaries of the three ocean basins, before spiraling southeastward and upward through the Antarctic Circumpolar Current. Upwelling is greatly enhanced at five major topographic features, associated with vigorous mesoscale eddy activity. Deep water reaches the upper ocean predominantly south of the Antarctic Circumpolar Current, with a spatially nonuniform distribution. The timescale for half of the deep water to upwell from 30° S to the mixed layer is ~60–90 years.

Tamsitt, V, Talley LD, Mazloff MR.  2019.  A deep eastern boundary current carrying Indian deep water south of Australia. Journal of Geophysical Research: Oceans. 124:2218-2238.   10.1029/2018jc014569   Abstract

In the Southern Hemisphere, the ocean's deep waters are predominantly transported from low to high latitudes via boundary currents. In addition to the Deep Western Boundary Currents, pathways along the eastern boundaries of the southern Atlantic, Indian, and Pacific transport deep water poleward into the Southern Ocean where these waters upwell to the sea surface. These deep eastern boundary currents and their physical drivers are not well characterized, particularly those carrying carbon and nutrient-rich deep waters from the Indian and Pacific basins. Here we describe the poleward deep eastern boundary current that carries Indian Deep Water along the southern boundary of Australia to the Southern Ocean using a combination of hydrographic observations and Lagrangian experiments in an eddy-permitting ocean state estimate. We find strong evidence for a deep boundary current carrying the low-oxygen, carbon-rich signature of Indian Deep Water extending between 1,500 and 3,000 m along the Australian continental slope, from 30°S to the Antarctic Circumpolar Current southwest of Tasmania. From the Lagrangian particles it is estimated that this pathway transports approximately 5.8 ± 1.3 Sv southward from 30°S to the northern boundary of the Antarctic Circumpolar Current. The volume transport of this pathway is highly variable and is closely correlated with the overlying westward volume transport of the Flinders Current.

Tamsitt, V, Abernathey RP, Mazloff MR, Wang J, Talley LD.  2018.  Transformation of deep water masses along Lagrangian upwelling pathways in the Southern Ocean. Journal of Geophysical Research: Oceans.   10.1002/2017JC013409   AbstractWebsite

Upwelling of northern deep waters in the Southern Ocean is fundamentally important for the closure of the global meridional overturning circulation and delivers carbon and nutrient‐rich deep waters to the sea surface. We quantify water mass transformation along upwelling pathways originating in the Atlantic, Indian, and Pacific and ending at the surface of the Southern Ocean using Lagrangian trajectories in an eddy‐permitting ocean state estimate. Recent related work shows that upwelling in the interior below about 400 m depth is localized at hot spots associated with major topographic features in the path of the Antarctic Circumpolar Current, while upwelling through the surface layer is more broadly distributed. In the ocean interior upwelling is largely isopycnal; Atlantic and to a lesser extent Indian Deep Waters cool and freshen while Pacific deep waters are more stable, leading to a homogenization of water mass properties. As upwelling water approaches the mixed layer, there is net strong transformation toward lighter densities due to mixing of freshwater, but there is a divergence in the density distribution as Upper Circumpolar Deep Water tends become lighter and dense Lower Circumpolar Deep Water tends to become denser. The spatial distribution of transformation shows more rapid transformation at eddy hot spots associated with major topography where density gradients are enhanced; however, the majority of cumulative density change along trajectories is achieved by background mixing. We compare the Lagrangian analysis to diagnosed Eulerian water mass transformation to attribute the mechanisms leading to the observed transformation.

Tamsitt, V, Talley LD, Mazloff MR, Cerovecki I.  2016.  Zonal variations in the Southern Ocean heat budget. Journal of Climate. 29:6563-6579.   10.1175/JCLI-D-15-0630.1   AbstractWebsite

The spatial structure of the upper ocean heat budget in the Antarctic Circumpolar Current (ACC) is investigated using the ⅙°, data-assimilating Southern Ocean State Estimate (SOSE) for 2005–10. The ACC circumpolar integrated budget shows that 0.27 PW of ocean heat gain from the atmosphere and 0.38 PW heat gain from divergence of geostrophic heat transport are balanced by −0.58 PW cooling by divergence of Ekman heat transport and −0.09 PW divergence of vertical heat transport. However, this circumpolar integrated balance obscures important zonal variations in the heat budget. The air–sea heat flux shows a zonally asymmetric pattern of ocean heat gain in the Indian and Atlantic sectors and ocean heat loss in the Pacific sector of the ACC. In the Atlantic and Indian sectors of the ACC, the surface ocean heat gain is primarily balanced by divergence of equatorward Ekman heat transport that cools the upper ocean. In the Pacific sector, surface ocean heat loss and cooling due to divergence of Ekman heat transport are balanced by warming due to divergence of geostrophic heat advection, which is similar to the dominant heat balance in the subtropical Agulhas Return Current. The divergence of horizontal and vertical eddy advection of heat is important for warming the upper ocean close to major topographic features, while the divergence of mean vertical heat advection is a weak cooling term. The results herein show that topographic steering and zonal asymmetry in air–sea exchange lead to substantial zonal asymmetries in the heat budget, which is important for understanding the upper cell of the overturning circulation.

Tishchenko, PY, Talley LD, Lobanov VB, Nedashkovskii AP, Pavlova GY, Sagalaev SG.  2007.  The influence of geochemical processes in the near-bottom layer on the hydrochemical characteristics of the waters of the Sea of Japan. Oceanology. 47:350-359.   10.1134/s0001437007030071   AbstractWebsite

According to the results of the international expedition aboard the R/Vs Roger Revelle and Professor Khromov in the summer 1999, areas with low oxygen contents (below 210 mu M/kg) and those with increased contents of dissolved inorganic carbon and phosphates were found that roughly coincided with one another. These areas are located near the bottom on the southwestern slope of the Tsushima Basin in the region of the Korea Strait and on the continental slope in the region of the Tatar Strait in the northern part of the sea at about 46 degrees N. The set of hydrochemical data points to a high geochemical activity in the near-bottom layer of the areas noted. This activity is confirmed by direct observations of the composition of the interstitial water in the sediments collected in the northern part of the sea during the expedition of R/V Akademik M.A. Lavrent'ev in 2003. It was supposed that the main cause of the increased geochemical activity is the runoff of suspended and dissolved matter from the Korea and Tatar straits. In the areas mentioned, the near-bottom waters are characterized by low values of the nitrogen-phosphorus ratio (below 10), which is geochemical proof of the denitrification process occurring under the conditions of high oxygen concentrations characteristic of the Sea of Japan. Based on the value of the annual production in the Sea of Japan, a rate of denitrification equal to 3.4 x 10(12) gN/year was calculated. Hence, it is confirmed that the geochemical processes in the near-bottom layer have a direct influence on the spatiotemporal characteristics of the hydrochemical properties of the waters of the Sea of Japan.

Tishchenko, PY, Talley LD, Nedashkovskii AP, Sagalaev SG, Zvalinskii VI.  2002.  Temporal variability of the hydrochemical properties of the waters of the Sea of Japan. Oceanology. 42:795-803. AbstractWebsite

Hydrochemical studies were performed in the Sea of Japan from onboard R/V Akademik Vinogradov in 1992 and R/Vs Roger Revelle and Professor Khromov in 1999. A comparison of the hydrochemical properties (concentrations of dissolved oxygen and nutrients and proteins of the carbonate system) of the waters of the Sea of Japan with those of the adjacent basins (the Sea of Okhotsk, Pacific Ocean, and East China Sea) demonstrates significant differences between them. In addition, a significant temporal variability of the hydrochemical properties of the intermediate and abyssal waters of the Sea of Japan was revealed. A general increase in the contents of inorganic forms of phosphorus, nitrogen, and normalized organic matter along with a general decrease in the oxygen concentration and normalized alkalinity with time was established. We suggest a model for an open basin, in which the principal reason for the observed features and temporal variability of the hydrochemical properties is related to the water exchange between the Sea of Japan and adjacent basins. A supposition is posed on the strong dependence of the water exchange on the variability of the intensity analysis direction of the major currents of the northwestern Pacific Ocean, especially the Kuroshio Current.

Tishchenko, PY, Talley LD, Lobanov VB, Zhabin IA, Luchm VA, Nedashkovskii AP, Sagalaev SG, Chichkin RV, Shkirnikova EM, Ponomarev VI, Masten D, Kang DJ, Kim KR.  2003.  Seasonal variability of the hydrochemical conditions in the sea of Japan. Oceanology. 43:643-655. AbstractWebsite

In the summer of 1999 and the winter of 2000, during international expeditions of R/Vs Professor Khromov and Roger Revelle, hydrological and hydrochemical studies of the Sea of Japan were performed. Comparing the hydrochemical characteristics of the Sea of Japan in the summer and winter seasons, we have found that the seasonal variability affects not only the upper quasihomogeneous layer but also the deeper layers. This variability is caused by the intensification of vertical mixing during the winter season. It was shown that the mixing intensification in the deep layers of the sea in the winter might be caused both by the slope convection and by the deep convection in the open part of the sea, penetrating deeper than 1000 in. It was found that the area of positive values of the biological constituent of the apparent oxygen consumption coincides with the area of deep convection. The climatic zoning in the distribution of partial pressure of carbon dioxide was revealed for both seasons. In the northwestern part of the sea, carbon dioxide is released into the atmosphere due to the deep convection in the winter and the heating process in the summer. The southern part of the sea absorbs the atmospheric carbon dioxide because of the process of photosynthesis and cooling of the waters supplied from the Korea Strait.