Improved modeling of Congo's hydrology for floods and droughts analysis and ENSO teleconnections

Wongchuig, Sly; Kitambo, Benjamin; Papa, Fabrice; Paris, Adrien; Fleischmann, Ayan Santos; Gal, Laetitia; Boucharel, Julien; Paiva, Rodrigo; Oliveira, Rômulo Jucá; Tshimanga, Raphael M.; Calmant, Stéphane

doi:10.1016/j.ejrh.2023.101563

Cited by 3 publications

(1 citation statement)

References 88 publications

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“…The Congo River outflow with long-term (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010) annual mean discharge of 40,662 m 3 /s (Alsdorf et al, 2016) creates a huge freshwater plume, whose space-time variability and dynamics have been extensively studied (Denamiel et al, 2013;Hopkins et al, 2013;Reul et al, 2014;Vic et al, 2014;Chao et al, 2015;Sorí et al, 2017;Munzimi et al, 2019;Phillipson and Toumi, 2019;Laraque et al, 2020;Houndegnonto et al, 2021;Martins and Stammer, 2022;Jarugula and McPhaden, 2023;Wongchuig et al, 2023). Similar to other river plumes, the Congo River plume could feature fronts in SST and SSS that could either bound the plume or could be embedded in the plume; however, this aspect of the Congo River outflow remained unexplored to date.…”

Section: Introductionmentioning

confidence: 99%

Salinity Fronts in the South Atlantic

Belkin,

Shen

2024

Preprint

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Seasonal climatology of salinity fronts in the South Atlantic has been created from satellite SMOS sea surface salinity (SSS) measurements, 2011-2019, processed at the Barcelona Expert Center of Remote Sensing (BEC) and provided as high-resolution (1/20°) SSS data. The SSS fronts are identified with narrow zones of enhanced horizontal gradient magnitude (GM) of SSS computed with the Belkin-O’Reilly algorithm. Seasonal climatologies are generated for large-scale open-ocean SSS fronts and for low-salinity regions maintained by the Rio de la Plata discharge, Magellan Strait outflow, Congo River discharge, and Benguela upwelling. To facilitate feature recognition in satellite imagery, the salinity gradient has been log-transformed, which improved visual contrast of gradient maps, revealing new features. A 2000-km-long triangular area in the eastern tropical-subtropical Atlantic is filled with regular quasi-meridional mesoscale striations that form a giant ripple field with a 100-km wave length extending from Africa toward the NE Brazil. South of the Tropical Front, within the subtropical high-salinity pool, a trans-ocean quasi-zonal narrow linear belt of SSS maximum is documented. The Smax belt shifts north-south seasonally while retaining its well-defined linear morphology, which is suggestive of a mechanism that maintains this feature. In the SW Atlantic, the Rio de la Plata plume expands in winter (June-July), reaching across the South Brazilian Bight, up to Cabo Frio (23°S) and beyond. The Plata estuarine front moves in and out seasonally. Farther south, the Magellan Strait outflow expands northward in winter up to 39-40°S to nearly join the Plata outflow. In the SE Atlantic, the Congo River plume spreads radially from the river mouth, with the spreading direction varying seasonally and interannually. The plume is often bordered from the south by a quasi-zonal front along 6°S. The diluted Congo River water spreads southward seasonally down to the thermal Angola-Benguela Front at 16°S. The Benguela upwelling is delineated by a meridional front, which extends north alongshore up to 20°S, where the low-salinity Benguela upwelling water meets the high-salinity tropical water (“Angola water”) to form a salinity front, which is separate from the thermal Angola-Benguela Front at 16°S. The Angola water thus forms a wedge between the low-salinity waters of the Congo River outflow in the north and Benguela upwelling in the south. This high-salinity wedge is bordered by salinity fronts that migrate north-south seasonally.

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Section: Introductionmentioning

confidence: 99%

Salinity Fronts in the South Atlantic

Belkin,

Shen

2024

Preprint

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Assessing uncertainties of a remote sensing-based discharge reflectance model for applications to large rivers of the Congo Basin

Kechnit,

Tshimanga,

Ammari

et al. 2024

Hydrological Sciences Journal

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Salinity Fronts in the South Atlantic

Belkin,

Shen

2024

Remote Sensing

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Monthly climatology data for salinity fronts in the South Atlantic have been created from satellite SMOS sea surface salinity (SSS) measurements taken from 2011–2019, processed at the Barcelona Expert Center of Remote Sensing (BEC), and provided as high-resolution (1/20°) daily SSS data. The SSS fronts have been identified with narrow zones of enhanced horizontal gradient magnitude (GM) of SSS, computed using the Belkin–O’Reilly algorithm (BOA). The SSS gradient fields generated by the BOA have been log-transformed to facilitate feature recognition. The log-transformation of SSS gradients markedly improved the visual contrast of gradient maps, which in turn allowed new features to be revealed and previously known features to be documented with a monthly temporal resolution and a mesoscale (~100 km) spatial resolution. Monthly climatologies were generated and analyzed for large-scale open-ocean SSS fronts and for low-salinity regions maintained by the Rio de la Plata discharge, Magellan Strait outflow, Congo River discharge, and Benguela Upwelling. A 2000 km-long triangular area between Africa and Brazil was found to be filled with regular quasi-meridional mesoscale striations that form a giant ripple field with a 100 km wave length. South of the Tropical Front, within the subtropical high-salinity pool, a trans-ocean quasi-zonal narrow linear belt of meridional SSS maximum (Smax) was documented. The meridional Smax belt shifts north–south seasonally while retaining its well-defined linear morphology, which is suggestive of a yet unidentified mechanism that maintains this feature. The Subtropical Frontal Zone (STFZ) consists of two tenuously connected fronts, western and eastern. The Brazil Current Front (BCF) extends SE between 40 and 45°S to join the subantarctic front (SAF). The STFZ trends NW–SE across the South Atlantic, seemingly merging with the SAF/BCF south of Africa to form a single front between 40 and 45°S. In the SW Atlantic, the Rio de la Plata plume migrates seasonally, expanding northward in winter (June–July) from 39°S into the South Brazilian Bight, up to Cabo Frio (23°S) and beyond. The inner Plata front moves in and out seasonally. Farther south, the Magellan Strait outflow expands northward in winter (June–July) from 53°S up to 39–40°S to nearly join the Plata outflow. In the SE Atlantic, the Congo River plume spreads radially from the river mouth, with the spreading direction varying seasonally. The plume is often bordered from the south by a quasi-zonal front along 6°S. The diluted Congo River water spreads southward seasonally down to the Angola–Benguela Front at 16°S. The Benguela Upwelling is delineated by a meridional front, which extends north alongshore up to 20°S, where the low-salinity Benguela Upwelling water forms a salinity front, which is separate from the thermal Angola–Benguela Front at 16°S. The high-salinity tropical water (“Angola water”) forms a wedge between the low-salinity waters of the Congo River outflow and Benguela Upwelling. This high-salinity wedge is bordered by salinity fronts that migrate north–south seasonally.

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Improved modeling of Congo's hydrology for floods and droughts analysis and ENSO teleconnections

Cited by 3 publications

References 88 publications

Salinity Fronts in the South Atlantic

Salinity Fronts in the South Atlantic

Assessing uncertainties of a remote sensing-based discharge reflectance model for applications to large rivers of the Congo Basin

Salinity Fronts in the South Atlantic

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