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  • AGU (American Geophysical Union)  (3)
  • Oceanography Society  (2)
  • Pergamon Press  (1)
  • Wiley-Blackwell  (1)
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  • 1
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    Kinematic Elements of Antarctic Intermediate Water in the western South Atlantic (1999)
    Pergamon Press
    In:  Deep Sea Research Part II: Topical Studies in Oceanography, 46 . pp. 355-392.
    Details
    Publication Date: 2020-08-05
    Description: The northward flowing Antarctic Intermediate Water (AAIW) is a major contributor to the large-scale meridional circulation of water masses in the Atlantic. Together with bottom and thermocline water, AAIW replaces North Atlantic Deep Water that penetrates into the South Atlantic from the North. On the northbound propagation of AAIW from its formation area in the south-western region of the Argentine Basin, the AAIW progresses through a complex spreading pattern at the base of the main thermocline. This paper presents trajectories of 75 subsurface floats, seeded at AAIW depth. The floats were acoustically tracked, covering a period from December 1992 to October 1996, Discussions of selected trajectories focus on mesoscale kinematic elements that contribute to the spreading of AAIW. In the equatorial region, intermittent westward and eastward currents were observed, suggesting a seasonal cycle of the AAIW flow direction. At tropical latitudes, just offshore the intermediate western boundary current, the southward advection of an anticyclonic eddy was observed between 5 degrees S and 11 degrees S. Farther offshore, the flow lacks an advective pattern and is governed by eddy diffusion. The westward subtropical gyre return current at about 28 degrees S shows considerable stability, with the mean kinetic energy to eddy kinetic energy ratio being around one. Farther south, the eastward deeper South Atlantic Current is dominated by large-scale meanders with particle velocities in excess of 60 cm s(-1). At the Brazil-Falkland Current Confluence Zone, a cyclonic eddy near 40 degrees S 50 degrees W seems to act as injector of freshly mixed AAIW into the subtropical gyre. In general, much of the mixing of the various blends of AAIW is due to the activity of mesoscale eddies, which frequently reoccupy similar positions. (C) 1999 Elsevier Science Ltd. All rights reserved.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/S0967-0645(98)00104-0
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    The intermediate depth circulation of the western South Atlantic (1999)
    AGU (American Geophysical Union)
    In:  Geophysical Research Letters, 26 . 21,3329-21,3332.
    Details
    Publication Date: 2018-02-13
    Description: The subsurface oceanic circulation is an important part of the Earth climate system. Subsurface currents traditionally are inferred indirectly from distributions of temperature and dissolved substances, occasionally supplemented by current meter measurements. Neutrally-buoyant floats however, now enable us to obtain for the first time directly measured intermediate depth velocity fields over large areas such as the western South Atlantic. Here, our combined data set provides unprecedented observations and quantification of key flow patterns, such as the Subtropical Gyre return flow (12 Sv; 1 Sverdrup = 10(6)m(3)s(-1)), its bifurcation near the Santos Plateau and the resulting continuous narrow and swift northward intermediate western boundary current (4 Sv). This northward flowing water passes through complex equatorial flows and finally enters into the North Atlantic.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1029/1999GL002355
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Intermediate water in the Brazil-Malvinas Confluence Zone: A Lagrangian view (1999)
    AGU (American Geophysical Union)
    In:  Journal of Geophysical Research: Oceans, 104 (C9). 21,063-21,082.
    Details
    Publication Date: 2018-04-27
    Description: The subsurface flow within the subantarctic and subtropical regions around the Brazil-Malvinas (Falkland) Confluence Zone is studied, using daily hydrographic and kinematic data from four subsurface floats and a hydrographic section parallel to the South American shelf. The float trajectories are mapped against sea surface flow patterns as visible in concurrent satellite sea surface temperature (SST) images, with focus on the November 1994 and October/November 1995 periods. The unprecedented employment of Lagrangian θ-S diagrams enables us to trace the advection of patches of fresh Antarctic Intermediate Water (AAIW) from the Confluence Zone into the subtropical region. The fresh AAIW consists of a mixture of subtropical AAIW and Malvinas Current core water. Within the subtropical gyre, these patches are discernible for extended periods and drift over long distances, reaching north to 34°S and east to 40°W. The cross-frontal migration of quasi-isobaric floats across the Confluence Zone from the subtropical to the subantarctic environment is observed on three occasions. The reverse process, float migration from a subpolar to a subtropical environment was observed once. These events were located near 40°S, 50°W, the site of a reoccurring cold core feature. Subsurface float and SST data comparison reveals similarities with analogous observations made in the Gulf Stream [Rossby, 1996] where cross-frontal processes were observed close to meander crests. The limited number of floats of this study and the complex structure of the Brazil-Malvinas Confluence Zone, however, restricts the analysis to a description of two events.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1029/1999JC900059
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Flow and recirculation of Antarctic Intermediate Water across the Rio Grande Rise (1997)
    AGU (American Geophysical Union)
    Details
    Publication Date: 2022-03-07
    Description: The flow of the low‐salinity Antarctic Intermediate Water (AAIW) at 700–1150 m depth across the Rio Grande Rise and the lower Santos Plateau is studied under the auspices of the World Ocean Circulation Experiment (WOCE) in the context of the Deep Basin Experiment. Our data set consists of several hydrographic sections, a collection of 15 RAFOS float trajectories, and records from 14 moored current meters. The data were gathered during different intervals between 1990 and 1994. The inferred flow field strongly supports a basinwide anticyclonic recirculation cell in the subtropical South Atlantic underneath the wind‐driven gyre. Its center, which appears to be southeast of the Rio Grande Rise, separates the eastward advection of AAIW below the South Atlantic Current from the westward flowing, recirculating AAIW. The two near‐shelf limbs closing the circumference of AAIW flow are formed in the east by the deep Benguela Current, potentially modulated by salty inflow of Indian Ocean Intermediate Water, and in the west by the Brazil Current system. Further important circulation elements are the Brazil‐Falkland (Malvinas) Confluence Zone at 40°S and an unnamed divergence at 28°S close to the 1000 m isobath. The resulting broad southward flow of AAIW augments the share of modified, i.e., saltier, intermediate water in the source region of the South Atlantic Current, while the smaller northward flow marks the source of a narrow equatorward Western Intermediate Boundary Current, ultimately leaving the South Atlantic. This shelf‐trapped jet is clearly documented in hydrographic data from 19°S and in nearby current meter records. The jet contrasts a sluggish flow across this latitude east of 35°W. A continuous flow of AAIW from its subpolar region in the southwestern Argentine Basin all along the western slope toward the equator appears unlikely between 35°S and 25°S.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Climate-Relevant Ocean Transport Measurements in the Atlantic and Arctic Oceans (2021)
    Oceanography Society
    Details
    Publication Date: 2024-04-08
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    A canonical EF-loop directs Ca2+-sensitivity in phospholipase C-η2 (2013)
    Wiley-Blackwell
    Details
    Publication Date: 2013-10-15
    Description: Phospholipase C-η (PLCη) enzymes are a class of phosphatidylinositol 4,5-bisphosphate-hydrolyzing enzymes involved in intracellular signaling. PLCη2 can sense Ca 2+ (stimulated by ∼1 µM free Ca 2+ ) suggesting that it can amplify transient Ca 2+ signals. PLCη enzymes possess an EF-hand domain composed of two EF-loops; a canonical 12-residue loop (EF-loop 1) and a non-canonical 13-residue loop (EF-loop 2). Ca 2+ -binding to synthetic peptides corresponding to EF-loops 1 and 2 of PLCη2 and EF-loop 1 of calmodulin (as a control) was examined by 2D-[ 1 H, 1 H] TOCSY NMR. Both PLCη2 EF-loop peptides bound Ca 2+ in a similar manner to that of the canonical calmodulin EF-loop 1, particularly at their N-terminus. A molecular model of the PLCη2 EF-hand domain, constructed based upon the structure of calmodulin, suggested both EF-loops may participate in Ca 2+ -binding. To determine whether the EF-hand is responsible for Ca 2+ -sensing, inositol phosphate accumulation was measured in COS7 cells transiently expressing wild-type or mutant PLCη2 proteins. Addition of 70 µM monensin (a Na + /H + antiporter that increases intracellular Ca 2+ ) induced a 4 to 7-fold increase in wild-type PLCη2 activity. In permeabilized cells, PLCη2 exhibited a ∼4-fold increase in activity in the presence of 1 µM free Ca 2+ . The D256A (EF-loop1) mutant exhibited a ∼10-fold reduction in Ca 2+ -sensitivity and was not activated by monensin, highlighting the involvement of EF-loop 1 in Ca 2+ -sensing. Involvement of EF-loop 2 was examined using D292A, H296A, Q297A and E304A mutants. Interestingly, the monensin responses and Ca 2+ -sensitivities were largely unaffected by the mutations, indicating that the non-canonical EF-loop 2 is not involved in Ca 2+ -sensing. J. Cell. Biochem. © 2013 Wiley Periodicals, Inc.
    Electronic ISSN: 0091-7419
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Published by Wiley-Blackwell
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    PAPER CURRENT
  • 7
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    The Argo Program : observing the global ocean with profiling floats (2009)
    Oceanography Society
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © Oceanography Society, 2009. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 22 no. 2 (2009): 34-43.
    Description: The Argo Program has created the first global array for observing the subsurface ocean. Argo arose from a compelling scientific need for climate-relevant ocean data; it was made possible by technology development and implemented through international collaboration. The float program and its data management system began with regional arrays in 1999, scaled up to global deployments by 2004, and achieved its target of 3000 active instruments in 2007. US Argo, supported by the National Oceanic and Atmospheric Administration and the Navy through the National Oceanographic Partnership Program, provides half of the floats in the international array, plus leadership in float technology, data management, data quality control, international coordination, and outreach. All Argo data are freely available without restriction, in real time and in research-quality forms. Uses of Argo data range from oceanographic research, climate research, and education, to operational applications in ocean data assimilation and seasonal-to-decadal prediction. Argo’s value grows as its data accumulate and their applications are better understood. Continuing advances in profiling float and sensor technologies open many exciting possibilities for Argo’s future, including expanding sampling into high latitudes and the deep ocean, improving near-surface sampling, and adding biogeochemical parameters.
    Description: The authors and their part of the Argo Program were supported by US Argo via the National Ocean Partnership Program, including NOAA Grants NA17RJ1231 (SIO–JIMO), NA17RJ1232 (UW–JISAO), and NA17RJ1223 (WHOI-CICOR).
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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    PAPER (OA)
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