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Holte, J, Talley LD, Gilson J, Roemmich D.  2017.  An Argo mixed layer climatology and database. Geophysical Research Letters. 44:5618-5626.   10.1002/2017gl073426   AbstractWebsite

A global climatology and database of mixed layer properties are computed from nearly 1,250,000 Argo profiles. The climatology is calculated with both a hybrid algorithm for detecting the mixed layer depth (MLD) and a standard threshold method. The climatology provides accurate information about the depth, properties, extent, and seasonal patterns of global mixed layers. The individual profile results in the database can be used to construct time series of mixed layer properties in specific regions of interest. The climatology and database are available online at . The MLDs calculated by the hybrid algorithm are shallower and generally more accurate than those of the threshold method, particularly in regions of deep winter mixed layers; the new climatology differs the most from existing mixed layer climatologies in these regions. Examples are presented from the Labrador and Irminger Seas, the Southern Ocean, and the North Atlantic Ocean near the Gulf Stream. In these regions the threshold method tends to overestimate winter MLDs by approximately 10% compared to the algorithm.

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.

Brambilla, E, Talley LD.  2008.  Subpolar Mode Water in the northeastern Atlantic: 1. Averaged properties and mean circulation. Journal of Geophysical Research-Oceans. 113   10.1029/2006jc004062   AbstractWebsite

Subpolar Mode Waters (SPMW) in the eastern North Atlantic subpolar gyre are investigated with hydrographic and Lagrangian data (surface drifters and isopycnal floats). Historical hydrographic data show that SPMWs are surface water masses with nearly uniform properties, confined between the ocean surface and the permanent pycnocline. SPMWs represented by densities 27.3(sigma theta), 27.4(sigma theta), and 27.5(sigma theta) are present in the eastern subpolar gyre and are influenced by the topography and the regional circulation. Construction of an absolute surface stream function from surface drifters shows that SPMWs are found along the mean path of each of the several branches of the North Atlantic Current (NAC) and their density increases gradually downstream. The Rockall Trough branch of the NAC carries 27.3(sigma theta), 27.4(sigma theta), and 27.5(sigma theta) SPMW toward the Iceland-Faroe Front. In the Iceland Basin, the Subarctic Front along the western flank of the Rockall Plateau carries a similar sequence of SPMW. The western side of the Central Iceland Basin branch of the NAC, on the other hand, veers westward and joins the East Reykjanes Ridge Current, feeding the 27.5(sigma theta) SPMW on the Reykjanes Ridge. The separation among the various NAC branches most likely explains the different properties that characterize the 27.5(sigma theta) SPMW found on the Reykjanes Ridge and on the Iceland-Faroe Ridge. Since the branches of the NAC have a dominant northeastward direction, the newly observed distribution of SPMW combined with the new stream function calculation modify the original hypothesis of McCartney and Talley (1982) of a smooth cyclonic pathway for SPMW advection and density increase around the subpolar gyre.

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.