Eddy characteristics in the South Indian Ocean as inferred from surface drifters

Zheng, Shaojun; Du, Yan; Li, Jiaxun; Cheng, Xuhua

doi:10.5194/os-11-361-2015

Cited by 30 publications

(23 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Figure b, which highlights the area where many AREN eddies are present over the period of interest, shows a clear link between these northeast formation regions and the Agulhas Retroflection. This pattern is very similar to the many large eddies detected from surface drifters documented by Zheng et al () .…”

Section: Results Of the Toeddies Methods Applied To Agulhas Ringssupporting

confidence: 89%

“…This eddy forms near Madagascar and remains very coherent until it reaches the Cape Basin. Furthermore, this type of eddies is also well captured by looping drifters (Lumpkin, ; Zheng et al, ) and the in situ data recorded by current meter moorings (Donohue et al, ). Many new detections of AREN eddies are also occurring in the open Indian ocean, which corresponds to the eastern part of our domain of study.…”

Section: Results Of the Toeddies Methods Applied To Agulhas Ringsmentioning

confidence: 90%

See 1 more Smart Citation

Anticyclonic Eddies Connecting the Western Boundaries of Indian and Atlantic Oceans

et al. 2018

View full text Add to dashboard Cite

The Indo‐Atlantic interocean exchanges achieved by Agulhas Rings are tightly linked to global ocean circulation and climate. Yet they are still poorly understood because they are difficult to identify and follow. We propose here an original assessment on Agulhas Rings, achieved by TOEddies, a new eddy identification and tracking algorithm that we applied over 24 years of satellite altimetry. Its main novelty lies in the detection of eddy splitting and merging events. These are particularly abundant and significantly impact the concept of a trajectory associated with a single eddy, which becomes less obvious than previously admitted. To overcome this complication, we have defined a network of segments that group together in relatively complex trajectories. Such a network provides an original assessment of the routes and the history of Agulhas Rings. It links 730,481 eddies into 6,363 segments that cluster into Agulhas Ring trajectories of different orders. Such an order depends on the affiliation of the eddies and segments, in a similar way as a tree of life. Among them, we have identified 122 order 0 trajectories that can be considered as the major trajectories associated to a single eddy, albeit it has undergone itself splitting and merging events. Despite the disappearance of many eddies in the altimeter signal in the Cape Basin, a significant fraction can be followed from the Indian Ocean to the South Brazil Current with, on average, 3.5 years to cross the entire South Atlantic.

show abstract

Section: Results Of the Toeddies Methods Applied To Agulhas Ringssupporting

confidence: 89%

Section: Results Of the Toeddies Methods Applied To Agulhas Ringsmentioning

confidence: 90%

Anticyclonic Eddies Connecting the Western Boundaries of Indian and Atlantic Oceans

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Surface as well as subsurface eddies connect the eastern to the western South Indian Ocean basins, along isopycnal layers. These pathways, corroborated by the eddy tracks in Figures c–f, are suggestive of a continuous eddy corridor between Australia and Madagascar, coinciding with the high zonal EKE band at 25

°

S (Figure a) where large eddies (R > 100 km) are observed, as shown by Zheng et al (). We can conclude that this is a preferential latitudinal band of propagation for SIDDIES and, therefore, we suggest to name this latitudinal band in the South Indian Ocean as the 'Corridor of SIDDIES’, analogous to the Canary Eddy Corridor (Sangrà et al, ).…”

Section: Resultssupporting

confidence: 82%

SIDDIES Corridor: A Major East‐West Pathway of Long‐Lived Surface and Subsurface Eddies Crossing the Subtropical South Indian Ocean

et al. 2018

View full text Add to dashboard Cite

South Indian Ocean eddies (SIDDIES), originating from a high evaporation region in the eastern Indian Ocean, are investigated by tracking individual eddies from satellite data and co‐located Argo floats. A subsurface‐eddy identification method, based on its steric dynamic height anomaly, is devised to assign Argo profiles to surface eddies (surfSIDDIES) or subsurface eddies (subSIDDIES). These westward‐propagating, long‐lived features (>3 months) prevail over a preferential latitudinal band, forming a permanent structure linking the eastern to the western Indian Ocean, that we call the 'SIDDIES Corridor’. Key features have been revealed in the mean thermohaline vertical structure of these eddies. Anticyclonic SIDDIES are characterized by positive subsurface salinity anomalies, with subSIDDIES not exhibiting negative surface anomalies, as opposed to surfSIDDIES. Cyclonic subSIDDIES also occur, but their related salinity anomalies are weaker. SubSIDDIES exhibit two cores of different temperature polarities in their surface and subsurface levels. Cyclonic subSIDDIES have their cores at around 150‐200 m depth along the 25.4‐25.8 kg m−3 potential density layer with anticyclonic subSIDDIES having their cores at 250‐300 m along the 26‐26.4 kg m−3 density layer. The SIDDIES corridor acts as a zonal pathway for both eddy‐types to advect water masses and biogeochemical properties across the basin. This study provides a new insight on heat/salt fluxes, showing that 58% (32%) of the total heat eddy‐flux is ascribed to cyclonic (anticyclonic) subSIDDIES, respectively, in the eastern South Indian Ocean. Anticyclonic subSIDDIES have also been found to be the sole high‐saline water eddy‐conveyor toward the western Indian Ocean.

show abstract

“…In the North and South Pacific, seasonal variations in the intensity of baroclinic instability associated with quasizonal jet can explain the observed seasonal variations of eddy kinetic energy (EKE) (Qiu, 1999;Qiu & Chen, 2004). The subtropical south Indian Ocean is also characterized by significant mesoscale eddy activity from observations of satellite altimetry and surface drifters (Feng et al, 2007(Feng et al, , 2005Jia et al, 2011aJia et al, , 2011bPalastanga et al, 2007;Zheng et al, 2015). Like in the North and South Pacific, the seasonal variation of EKE in the southeast Indian Ocean (SEIO) is also modulated by baroclinic instability (Jia et al, 2011b;Palastanga et al, 2007;Siedler et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Interannual Variability of Eddy Kinetic Energy in the Subtropical Southeast Indian Ocean Associated With the El Niño‐Southern Oscillation

Zheng

Feng

et al. 2018

JGR Oceans

Self Cite

View full text Add to dashboard Cite

Interannual variability of eddy kinetic energy (EKE) in the subtropical southeast Indian Ocean (SEIO) is investigated using satellite observations in three regions in the 20°S–35°S latitude band: R1 (108°E–115°E), R2 (100°E–108°E), and R3 (60°E–100°E). The El Niño‐Southern Oscillation (ENSO) plays an important role in modulating the interannual variability of EKE in the SEIO. EKE in the three regions shows negative correlations with the Nino3.4, lagging Nino3.4 by 2, 14, and 22 months, respectively. In R1, the ENSO modulates the interannual variability of EKE through influencing baroclinic instability of meridional velocity shear between the upper poleward Leeuwin Current (LC) and the underlying equatorward Leeuwin Undercurrent (LUC). During La Niña (El Niño) year, both the poleward LC and equatorward LUC strengthened (weakened) due to the high (low) sea level anomaly (SLA) propagating from the Pacific Ocean as Rossby wave under geostrophic equilibrium, and baroclinic instability of vertical shear enhanced (slackened), further induced the strong (weak) EKE in the eastern boundary. In R2, the ENSO modulates the interannual variability of EKE through influencing baroclinic instability of zonal velocity shear between the central and southern branches of the upper eastward South Indian Countercurrent (SICC) and the lower extending westward South Equatorial Current (SEC). In R3, both the ENSO and the Southern Annual Mode modulate the interannual variability of EKE through influencing baroclinic instability of zonal velocity shear between the SICC and SEC. The interannual variability of EKE in the interior SEIO could be influenced by westward propagation of EKE originated from eastern boundary.

show abstract

Eddy characteristics in the South Indian Ocean as inferred from surface drifters

Cited by 30 publications

References 62 publications

Anticyclonic Eddies Connecting the Western Boundaries of Indian and Atlantic Oceans

Anticyclonic Eddies Connecting the Western Boundaries of Indian and Atlantic Oceans

SIDDIES Corridor: A Major East‐West Pathway of Long‐Lived Surface and Subsurface Eddies Crossing the Subtropical South Indian Ocean

Interannual Variability of Eddy Kinetic Energy in the Subtropical Southeast Indian Ocean Associated With the El Niño‐Southern Oscillation

Contact Info

Product

Resources

About