Red Sea Intermediate Water in the source regions of the Agulhas Current

Roman, Raymond; Lütjeharms, J. R. E.

doi:10.1016/j.dsr.2009.01.003

Cited by 17 publications

(17 citation statements)

References 28 publications

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“…These few unusually saline stations in the south suggest a mixing of Antarctic Intermediate and Red Sea Intermediate Water masses and reflect the influence of the anti‐cyclonic eddy in transporting RSIW southwards in an intermittent fashion. This agrees with recent findings by Roman and Lutjeharms [2007, 2009]. Those profiles extending into the Deep and Bottom waters tend to merge near a salinity of 34.8, and show little meridional or along‐section variation.…”

Section: Resultssupporting

confidence: 92%

“…Previous studies have shown that contributions from the Mozambique Channel significantly influence water mass properties in the Agulhas Current [e.g., DiMarco et al , 2002; Roman and Lutjeharms , 2009]. It has also been demonstrated that at least some of these anomalous water signals remain evident as far downstream as Agulhas Rings [ Roman and Lutjeharms , 2007] and therefore contribute to the flux into the South Atlantic.…”

Section: Discussionmentioning

confidence: 99%

“…In contrast, the eddy was depleted oxygen. These strong anomalies suggest that the Mozambique Channel eddies may influence the water mass characteristics of the Agulhas Current [e.g., Roman and Lutjeharms , 2009] into which they may partially and intermittently feed, and perhaps ultimately the physical and chemical properties of the South Atlantic basin via Agulhas leakage [e.g., Roman and Lutjeharms , 2007].…”

Section: Discussionmentioning

confidence: 99%

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Observed characteristics of Mozambique Channel eddies

et al. 2010

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[1] The flow in the Mozambique Channel is dominated by large, southward propagating, anti-cyclonic eddies, as opposed to a steady western boundary current. These Mozambique Channel eddies feed their waters into the Agulhas Current system, where they are thought to have a significant influence on the formation of the Natal Pulse and Agulhas Ring shedding. Here we use in situ hydrographic and nutrient data, together with satellite altimetry and surface velocity profilers to provide a detailed characterization of the Mozambique Channel eddies. Two warm eddies in the Channel at 20°S and 24°S had diameters of over 200 km. They rotated anti-cyclonically with a tangential velocity of over 0.5 m.s . Vertical sections show that the eddies reached to the bottom of the water column. Relative to the surrounding waters, the features were warm and saline. The total heat and salt anomalies for the southernmost eddy were computed relative to a reference station close by. At 24°S the total anomalies were 1.3 × 10 20 J and 6.9 × 10 12 kg, respectively, being on par with Agulhas rings. Mozambique Channel eddies thus have the potential to form a major contribution to the southward eddy heat flux in the Agulhas Current system. The feature also had positive nutrient and negative oxygen anomalies. The large magnitude of the water mass anomalies within the eddy suggests that interannual variability in Mozambique Channel eddy numbers would have a significant impact on downstream water mass characteristics.

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Section: Resultssupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Observed characteristics of Mozambique Channel eddies

et al. 2010

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“…A better understanding of the ocean circulation at temporal and spatial resolutions appropriate to these environmental issues will be valuable. However, this part of the East African coastal ocean has been grossly undersampled in comparison to neighboring areas such as the Somali coast and the Arabian Gulf [e.g., Vimal Kumar et al ., ; Smith et al ., ], the Red Sea [e.g., Roman and Lutjeharms , ], and the Mozambique Channel [e.g., van der Werf et al ., ; Ridderinkhof et al ., ; da Silva et al ., ; Nauw et al ., ; Matano et al ., ]. Historically, the undersampling is due to economical constraints of the local countries and the remoteness of the region, far from major oceanographic research institutes.…”

Section: Introductionmentioning

confidence: 99%

Characterizing the circulation off the Kenyan‐Tanzanian coast using an ocean model

et al. 2016

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The Kenyan‐Tanzanian coastal region in the western Indian Ocean faces several environmental challenges including coral reef conservation, fisheries management, coastal erosion, and nearshore pollution. The region lacks hydrodynamic records and oceanographic studies at adequate spatial and temporal scales to provide information relevant to the local environmental issues. We have developed a 4 km horizontal resolution ocean circulation model of the region: the Kenyan‐Tanzanian Coastal Model (KTCM) that provides coastal circulation and hydrography with higher resolution than previous models and observational studies of this region. Comparisons to temperature profiles, satellite‐derived sea surface temperature and sea surface height anomaly fields, indicate that the model reproduces the main features of the regional circulation, while greatly increasing the details of the nearshore circulation. We describe the seasonal ocean circulation and hydrography of the Kenyan‐Tanzanian coastal region based on a climatology of 8 years (2000–2007) of the KTCM simulations. The regional monsoon seasonality produces two distinct coastal circulation regimes: (1) during December–March, there are relatively sluggish shelf flows and (2) during April–November, there are strong northward transports. Simulations from the model will be useful for examining dispersal of pollutants and spatial connectivity of coral reef species.

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“…[]. The influence of RSIW is observed throughout the Comoros Basin indicating that similar to the transport of this water mass through the Mozambique Channel [ de Ruijter et al ., ; Roman and Lutjeharms , ], it spreads throughout the basin at intermediate levels within the core of mesoscale eddies. The RSIW (AAIW) observed in the Comoros Basin is less (more) saline than the RSIW (AAIW) in the Mozambique Channel.…”

Section: Discussionmentioning

confidence: 99%

First dedicated hydrographic survey of the Comoros Basin

et al. 2016

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The Comoros Basin, a region of eddies that propagate into the Mozambique Channel and subsequently the Agulhas Current, has not been well studied. This paper presents the findings from the first dedicated research cruise in the basin. ADCP data collected during the cruise show that the circulation in the Comoros Basin is dominated by the strong westward flowing North East Madagascar Current, which bifurcates twice: once upon encountering the Davie Ridge and again upon reaching the East African coast. One of the branches flows southward along the African coastline and appears to continue into the Mozambique Channel while the other branch turns northward to become the East African Coastal Current. The ADCP data also show evidence of a cyclonic eddy along the northwest coast of Madagascar. Water mass analysis indicates that all the major Indian Ocean water masses are present in the Comoros Basin. Surprisingly, North Atlantic Deep Water, a water mass previously assumed to only occur south of ∼16°S in the Mozambique Channel, was found to be present in the basin at depths below 2000 m. Antarctic Intermediate Water is found to enter the basin via two routes; from the west within the North East Madagascar Current and from the south within the northward flowing Mozambique Undercurrent.

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Red Sea Intermediate Water in the source regions of the Agulhas Current

Cited by 17 publications

References 28 publications

Observed characteristics of Mozambique Channel eddies

Observed characteristics of Mozambique Channel eddies

Characterizing the circulation off the Kenyan‐Tanzanian coast using an ocean model

First dedicated hydrographic survey of the Comoros Basin

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