Aspects of the Antarctic Circumpolar Current dynamics investigated with drifter data

Trani, Marilisa; Falco, Pierpaolo; Zambianchi, Enrico; Sallée, Jean‐Baptiste

doi:10.1016/j.pocean.2014.05.001

Cited by 12 publications

(14 citation statements)

References 84 publications

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“…Similarly, the annual residuals of altimetry velocities were obtained in each bin by subtracting the altimetry mean velocity over the period 1995-2017 (U' SLA = U SLA -⟨U SLA ⟩ 1995−2017 ). These residuals were then used to estimate (Thompson & Naveira Garabato, 2014;Trani et al, 2014). Outside the frontal belt, large EKE values are associated with migration of eddies, as observed southeast of New Zealand (50°S to 180°W), where the eddies detached from the ACC move northeastward along the steep sides of the Campbell Plateau (Cotroneo et al, 2013).…”

Section: Eke From Drifter and Altimetry Datamentioning

confidence: 99%

“…Interannual maps of dmEHF, EKE DR anomalies (defined with respect to the mean field of EKE DR in 1995-2017), and EKE SLA anomalies (defined with respect to the mean field of EKE SLA in 1995-2017) were estimated in the period characterized by positive (2000-2002, 2009, and 2011-2017) and negative (1995-1999 and 2004-2008) anomalies of EKE SLA (defined hereafter as EKE + and EKE − , respectively, with the eventual addition of the subscript DR or SLA according to the data set used) and for the two decades 1995-2006 and 2007-2017. The decades were selected according to three goals: (1) to make a comparison between the period 1995-2006 as analyzed by Trani et al (2011Trani et al ( , 2014 and the following decade (2007-2017), (2) to compare two periods where the EKE SLA anomaly shows very different characteristics and assess how and if these differences affect the distribution and intensity of the dmEHF, and (3) to compare a period in which the SAM index is always positive (2007-2017) with a period (1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006) in which it shows 2 years with negative values. Bins with less than 100 observations are not considered.…”

Section: Meridional Ehfsmentioning

confidence: 99%

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Response of the Pacific Sector of the Southern Ocean to Wind Stress Variability From 1995 to 2017

et al. 2020

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Drifter, satellite, expendable bathythermograph (XBT), and Argo float data are used to study the response of the Pacific Sector of the Southern Ocean (PSSO) to the wind stress field in the period 1995-2017, in terms of eddy field, water mass transport, and heat fluxes at large and regional scales. Increasing wind stress over the PSSO in those two decades led to a growth of the Eddy Kinetic Energy (EKE) in the region of the Antarctic Circumpolar Current (ACC). Increases of the EKE occur with delays of 1-4 years with respect to peaks in the zonal component of the wind stress. The persistent ACC meander located south of New Zealand (between 150°E and 180°W and 50°S to 66°S) responds to the interannual wind variations earlier than the entire ACC branch in the PSSO. In the same area, an estimate of the ACC transport based on in situ data shows interannual variability but no significant decadal trend over the study period. The effects of the EKE variability on the meridional eddy heat fluxes are significant on interannual scales. The strengthening of the EKE field leads to a local increase in the poleward meridional eddy heat fluxes in the PSSO, especially in the ACC band. The weakening of the EKE field defines an area of equatorward meridional eddy heat fluxes in the middle of the PSSO (south of 40°S, between 130°W and 160°W) and prevalent poleward fluxes in the further western and eastern regions.

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Section: Eke From Drifter and Altimetry Datamentioning

confidence: 99%

Section: Meridional Ehfsmentioning

confidence: 99%

Response of the Pacific Sector of the Southern Ocean to Wind Stress Variability From 1995 to 2017

et al. 2020

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“…Poleward surface transport across the North Atlantic Current occurs either in a narrow near‐shore flow (Rypina et al, ) or at depth (Burkholder & Lozier, ). The Antarctic Circumpolar Current and Kuroshio current have also been studied with drifter data, highlighting the role played by fronts in restricting drifter movement (Niiler et al, ; Trani et al, ).…”

Section: Introductionmentioning

confidence: 99%

Surface Connectivity and Interocean Exchanges From Drifter‐Based Transition Matrices

McAdam

Sebille

2018

JGR Oceans

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Global surface transport in the ocean can be represented by using the observed trajectories of drifters to calculate probability distribution functions. The oceanographic applications of the Markov Chain approach to modeling include tracking of floating debris and water masses, globally and on yearly‐to‐centennial time scales. Here we analyze the error inherent with mapping trajectories onto a grid and the consequences for ocean transport modeling and detection of accumulation structures. A sensitivity analysis of Markov Chain parameters is performed in an idealized Stommel gyre and western boundary current as well as with observed ocean drifters, complementing previous studies on widespread floating debris accumulation. Focusing on two key areas of interocean exchange—the Agulhas system and the North Atlantic intergyre transport barrier—we assess the capacity of the Markov Chain methodology to detect surface connectivity and dynamic transport barriers. Finally, we extend the methodology's functionality to separate the geostrophic and nongeostrophic contributions to interocean exchange in these key regions.

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“…Dispersion in the Southern Ocean has received considerably less attention than in other parts of the world ocean [ Trani et al ., ]. Although single‐particle dispersion studies have been undertaken in the region [ Sallée et al ., ], no experiment using paired drifters has been reported.…”

Section: Introductionmentioning

confidence: 99%

Pairwise surface drifter separation in the western Pacific sector of the Southern Ocean

et al. 2015

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The Southern Ocean plays a critical role in global climate, yet the mixing properties of the circulation in this part of the ocean remain poorly understood. Here dispersion in the vicinity of the Southern Antarctic Circumpolar Current Front, one of the branches of the Antarctic Circumpolar Current, is studied using 10 pairs of surface drifters deployed systematically across the frontal jet and its flanks. Drifter pairs were deployed with an initial separation of 13 m and report their position every hour. The separation of the pairs over 7 months, in terms of their Finite‐Scale Lyapunov Exponents (FSLE), dispersion, and diffusivity, is characterized and related to expected behavior from Quasi‐Geostrophic (QG) and Surface Quasi‐Geostrophic (SQG) theories. The FSLE analysis reveals two submesoscale regimes, with SQG‐like behavior at scales below 3.2 km and mixed QG/SQG behavior at scales between 3.2 and 73 km. The dispersion analysis, however, suggests QG‐like behavior for the smallest scales. Both dispersion and diffusivity appear isotropic for scales up to 500 km. Finally, there is no clear indication of a cross‐jet variation of drifter dispersion.

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Aspects of the Antarctic Circumpolar Current dynamics investigated with drifter data

Cited by 12 publications

References 84 publications

Response of the Pacific Sector of the Southern Ocean to Wind Stress Variability From 1995 to 2017

Response of the Pacific Sector of the Southern Ocean to Wind Stress Variability From 1995 to 2017

Surface Connectivity and Interocean Exchanges From Drifter‐Based Transition Matrices

Pairwise surface drifter separation in the western Pacific sector of the Southern Ocean

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