Impact of offshore eddies on shelf circulation and river plumes of the Sofala Bank, Mozambique Channel

Malauene, Bernardino S.; Moloney, Coleen L.; Lett, Christophe; Roberts, Michael J.; Marsac, Fransic; Penven, Pierrick

doi:10.1016/j.jmarsys.2018.05.001

Cited by 14 publications

(21 citation statements)

References 45 publications

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“…By releasing passive dyes together with the river discharge in the hydrodynamical model, Marta-Almeida et al (2021) showed that the local river plumes are confined to the inner shelf because the strong and persistent large-scale Brazil Current flowing southward over the slope prevents the river plumes from interaction with offshore oceanic mesoscale dynamics. The effect of mesoscale eddies on river plumes was conducted in the Agulhas Mozambique Channel region (Malauene et al, 2018), where the circulation is dominated by trains of intermittent, passing mesoscale eddies. They showed that offshore passing eddies modulate river plumes direction and spread depends on their strength and proximity to the shelf.…”

Section: Role Of Mesoscale Circulation On River Plumesmentioning

confidence: 99%

Impact of Mesoscale Circulation on the Structure of River Plumes During Large Rainfall Events Inshore of the East Australian Current

Roughan

Kerry

et al. 2022

Front. Mar. Sci.

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Estuarine outflow can have a significant impact on physical and ecological systems in the coastal ocean. Along southeastern Australia, inshore of the East Australian Current, the shelf is narrow, the coastal circulation is advection dominated, and river estuarine outflow tends to be low, hence river plumes have largely been ignored. For these reasons, we lack an understanding of the spatial and temporal evolution of river plumes during large rainfall events (which are projected to increase in frequency and intensity), and the interaction of the mesoscale circulation with the estuarine outflow remains to be explored. Using a high-resolution (750 m) hydrodynamic model, we simulate idealized plumes from 4 estuaries during three different mesoscale circulation scenarios and investigate the spatial and temporal evolution of the estuarine outflow under two contrasting rainfall events (normal and large). We explore the plume from the largest of the 4 rivers, the Hawkesbury River, to understand the impact of the mesoscale circulation. During the first EAC mode, the plume spreads both northward and southeastward. The offshore spread of the plume is the largest in this scenario (~12.5 km east of the river mouth) in the wet event. In the second EAC mode, this plume dispersal is toward the north and east, driven by the proximity of a cyclonic eddy on the shelf, with an eastward extension of 11 km. In the third EAC mode, most of this river plume spreads southward with some to the north, again dictated by the position of the cyclonic eddy. The cross-shelf dispersal is a minimum of 9.5 km from the river mouth. It takes around 6 days for the freshwater spatial extent of the plume in the wet event to return to the base case. These results show the importance of mesoscale EAC circulation on the shelf circulation when considering river plumes dispersal. Knowledge of the ultimate fate of riverborne material, dilution and cumulative effects will enable better environmental management of this dynamic region for the local government.

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Section: Role Of Mesoscale Circulation On River Plumesmentioning

confidence: 99%

Impact of Mesoscale Circulation on the Structure of River Plumes During Large Rainfall Events Inshore of the East Australian Current

Roughan

Kerry

et al. 2022

Front. Mar. Sci.

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“…Conversely, central and southern Mozambique are warming more slowly than the north [25], corroborating the medium to low climate exposure scores there. Further, previous studies described cool water lenses on the southern Sofala Bank [57,58], as well as cool cyclonic eddies in the Delagoa Bight in southern Mozambique [59]. Another study describes the upwelling cell and quasi-permanent cyclonic eddy off Angoche, with upwelling uplifting deep cold water to the surface [60], which explains the localised moderate exposure SST in this region around 16˚S.…”

Section: Plos Climatementioning

confidence: 88%

A rapid approach to assessing the vulnerability of Mozambican fisheries’ species to climate change

Fennessy,

Quick,

Mutombene

et al. 2024

PLOS Clim

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Mozambique is amongst the most vulnerable of Western Indian Ocean (WIO] countries to the impacts of climate change on its marine fisheries. We used rapid assessment methods to evaluate sensitivity, exposure and vulnerability of fisheries species to climate change, appropriate for data-deficient, developing countries in the region. Species were selected based on their importance in industrial and artisanal fisheries’ landings, further prioritized by local experts. Species’ attributes likely to be sensitive to climate change were identified and scored, utilizing life history or biological characteristics. Sea Surface Temperature (SST] was the most prominent climate exposure factor and for which we could confidently predict likely future change. Most species had low or medium overall sensitivity to climate change, with only eight considered highly sensitive. Climate exposure (SST] scores were high off northern Mozambique, while the central and southern regions were generally of medium exposure. Ten species received a High vulnerability score, 14 were Medium, and 16 had a Low vulnerability score. The highly vulnerable species were all fishes, apart from one crustacean; 4 of the 9 were strongly estuarine-associated; the most vulnerable species was the parrotfish Scarus ghobban. This is the first attempt to use a rapid, semi-quantitative, specialist- and trait-based vulnerability assessment of the anticipated effect of climate change on marine fisheries species in the WIO. Challenges experienced were data paucity, limited resources, the large study area, and the complex oceanography of the region. However, a simple methodology was developed, derived from efforts elsewhere, and which can be used to undertake similar assessments for other WIO countries. Raised awareness of climate change among small-scale fishing communities is a necessity, combined with adaptation by promoting fisheries co-management. Also required is support from government to ensure that people can be flexible to change.

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“…The slope parameter was 0.25, which prevented horizontal pressure gradient errors (Ismail and Ribbe, 2019). The bottom friction coefficient was calculated using logarithmic law (bottom roughness = 0.01) (Malauene et al, 2018). Ganju and Sherwood, (2010) provided further details regarding the algorithm that parameterizes bottom roughness in an ocean model.…”

Section: Methodsmentioning

confidence: 99%

An Evaluation of a 1/18o Resolution Regional Ocean Circulation Model of CROCO in the Southern Sunda Shelf

et al. 2023

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The Coastal and Regional Ocean Community Model (CROCO) was applied to simulate the three dimensional ocean circulation on the southern Sunda Shelf with a horizontal resolution of 1/18o and 40 vertical layers. This configuration is called as CROCO18-SSS. The initial and open boundary conditions were derived from a global reanalysis product at a resolution of 1/12o from the Copernicus Marine Environment Monitoring Service (CMEMS). The regional model was driven by atmospheric, tides, and river discharges data from a wide variety of datasets, each with a different resolution. To test the model performance and capabilities of the CROCO18-SSS model outputs including sea level anomaly, current velocity, temperature, salinity, and volume transport, we have compared in the simulation results with other reanalysis product and satellite-derived datasets. The CROCO18-SSS model outputs reproduced the regional ocean circulation well from observations and reanalysis products. For example, the reversal of the monsoonal current in the southern sunda shelf, as well as strong persistent southward Makassar throughflow and their interaction in the southern Makassar Strait, can be seen clearly. The vertical structure of the zonal current component was comparable to that of the reanalysis product reference. The seasonal shift in temperature and salinity, with the water becoming colder and saltier during the northwest monsoon and warmer and fresher during the southeast monsoon, was also accurately reproduced by the CROCO18-SSS model. Additionally, the mean volume transport calculated by the CROCO18-SSS model for the Makassar and Karimata Straits was comparable to that reported in previous studies.

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Impact of offshore eddies on shelf circulation and river plumes of the Sofala Bank, Mozambique Channel

Cited by 14 publications

References 45 publications

Impact of Mesoscale Circulation on the Structure of River Plumes During Large Rainfall Events Inshore of the East Australian Current

Impact of Mesoscale Circulation on the Structure of River Plumes During Large Rainfall Events Inshore of the East Australian Current

A rapid approach to assessing the vulnerability of Mozambican fisheries’ species to climate change

An Evaluation of a 1/18o Resolution Regional Ocean Circulation Model of CROCO in the Southern Sunda Shelf

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