scholarly journals Fate of the Amazon River dissolved organic matter in the tropical Atlantic Ocean

2015 ◽  
Vol 29 (5) ◽  
pp. 677-690 ◽  
Author(s):  
Patricia M. Medeiros ◽  
Michael Seidel ◽  
Nicholas D. Ward ◽  
Edward J. Carpenter ◽  
Helga R. Gomes ◽  
...  
Keyword(s):  
Organic Matter ◽  
Atlantic Ocean ◽  
Dissolved Organic Matter ◽  
Amazon River ◽  
Tropical Atlantic ◽  
Tropical Atlantic Ocean

scholarly journals Contribution of the Amazon River Discharge to Regional Sea Level in the Tropical Atlantic Ocean

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2348 ◽  
Author(s):  
Pierrick Giffard ◽  
William Llovel ◽  
Julien Jouanno ◽  
Guillaume Morvan ◽  
Bertrand Decharme
Keyword(s):  
Atlantic Ocean ◽  
Interannual Variability ◽  
Sea Level ◽  
River Discharge ◽  
River Mouth ◽  
Amazon River ◽  
Tropical Atlantic ◽  
Tropical Atlantic Ocean ◽  
Seasonal And Interannual Variability ◽  
Mean State

The Amazon River is by far the largest river by volume of water in the world, representing around 17% of the global riverine discharge to the oceans. Recent studies suggested that its impact on sea level is potentially important at global and regional scales. This study uses a set of regional simulations based on the ocean model NEMO to quantify the influence of the Amazon runoff on sea level in the Tropical Atlantic Ocean. The model is forced at its boundaries with daily fields from the ocean reanalysis GLORYS2V4. Air-sea fluxes are computed using atmospheric variables from DFS5.2, which is a bias-corrected version of ERAinterim reanalysis. The particularity of this study is that interannual daily runoffs from the up-to-date ISBA-CTRIP land surface model are used. Firstly, mean state of sea level is investigated through a comparison between a simulation with an interannual river discharge and a simulation without any Amazon runoff. Then, the impact of the Amazon River on seasonal and interannual variability of sea level is examined. It was shown that the Amazon River has a local contribution to the mean state sea level at the river mouth but also a remote contribution of 3.3 cm around the whole Caribbean Archipelago, a region threatened by the actual sea level rise. This effect is mostly due to a halosteric sea level contribution for the upper 250 m of the ocean. This occurs in response to the large scale advection of the plume and the downward mixing of subsurface waters at winter time. The Amazon discharge also induces an indirect thermosteric sea level contribution. However, this contribution is of second order and tends to counterbalance the halosteric sea level contribution. Regional mass redistributions are also observed and consist in a 8 cm decrease of the sea level at the river mouth and a 4.5 increases on continental shelves of the Gulf of Mexico and Caribbean Sea. In terms of variability, simulations indicate that the Amazon discharge may contributes to 23% and 12% of the seasonal and interannual sea level variances in the Caribbean Archipelago area. These variances are first explained by the Amazon time mean discharge and show very weak sensitivity to the seasonal and interannual variability of the Amazon runoff.

scholarly journals Correction to: Weakened SST variability in the tropical Atlantic Ocean since 2000

2021 ◽  
Author(s):  
Arthur Prigent ◽  
Joke F. Lübbecke ◽  
Tobias Bayr ◽  
Mojib Latif ◽  
Christian Wengel
Keyword(s):  
Atlantic Ocean ◽  
Tropical Atlantic ◽  
Tropical Atlantic Ocean ◽  
Sst Variability

scholarly journals Simulated Dust Aerosol Impacts on Western Sahelian Rainfall: Importance of Ocean Coupling

2018 ◽  
Vol 31 (22) ◽  
pp. 9107-9124 ◽  
Author(s):  
Asha K. Jordan ◽  
Anand Gnanadesikan ◽  
Benjamin Zaitchik
Keyword(s):  
Atlantic Ocean ◽  
North Africa ◽  
Negative Impact ◽  
Positive Impact ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Tropical Atlantic ◽  
Tropical Atlantic Ocean ◽  
Ocean Atmosphere ◽  
Sahel Region ◽  
Dust Precipitation

North Africa is the world’s largest source of mineral dust, and this dust has potentially significant impacts on precipitation. Yet there is no consensus in published studies regarding the sign or magnitude of dust impacts on rainfall in either the highly climate-sensitive Sahel region of North Africa or the neighboring tropical Atlantic Ocean. Here the Geophysical Fluid Dynamics Laboratory (GFDL) Climate Model 2 (GFDL CM2.0) with Modular Ocean Model, version 4.1 (MOM4.1), run at coarse resolution (CM2Mc) is applied to investigate one poorly characterized aspect of dust–precipitation dynamics: the importance of sea surface temperature (SST) changes in mediating the atmospheric response to dust. Two model experiments were performed: one comparing Dust-On to Dust-Off simulations in the absence of ocean–atmosphere coupling, and the second comparing Dust-On to Dust-Off with the ocean fully coupled. Results indicate that SST changes in the coupled experiment reduce the magnitude of dust impacts on Sahel rainfall and flip the sign of the precipitation response over the nearby ocean. Over the Sahel, CM2Mc simulates a net positive impact of dust on monsoon season rainfall, but ocean–atmosphere coupling in the presence of dust decreases the inflow of water vapor, reducing the amount by which dust enhances rainfall. Over the tropical Atlantic Ocean, dust leads to SST cooling in the coupled experiment, resulting in increased static stability that overrides the warming-induced increase in convection observed in the uncoupled experiment and yields a net negative impact of dust on precipitation. These model results highlight the potential importance of SST changes in dust–precipitation dynamics in North Africa and neighboring regions.

scholarly journals Impact of intraseasonal wind bursts on sea surface temperature variability in the far eastern tropical Atlantic Ocean during boreal spring 2005 and 2006: focus on the mid-May 2005 event

Ocean Science ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. 849-869 ◽  
Author(s):  
Gaëlle Herbert ◽  
Bernard Bourlès
Keyword(s):  
Atlantic Ocean ◽  
Surface Temperature ◽  
Kelvin Waves ◽  
Sea Surface ◽  
Tropical Atlantic ◽  
Gulf Of Guinea ◽  
Atmospheric Conditions ◽  
Tropical Atlantic Ocean ◽  
Boreal Spring ◽  
Wind Bursts

Abstract. The impact of boreal spring intraseasonal wind bursts on sea surface temperature variability in the eastern tropical Atlantic Ocean in 2005 and 2006 is investigated using numerical simulation and observations. We especially focus on the coastal region east of 5° E and between the Equator and 7° S that has not been studied in detail so far. For both years, the southerly wind anomalies induced cooling episodes through (i) upwelling processes, (ii) vertical mixing due to the vertical shear of the current, and for some particular events (iii) a decrease in incoming surface shortwave radiation. The strength of the cooling episodes was modulated by subsurface conditions affected by the arrival of Kelvin waves from the west influencing the depth of the thermocline. Once impinging the eastern boundary, the Kelvin waves excited westward-propagating Rossby waves, which combined with the effect of enhanced westward surface currents contributed to the westward extension of the cold water. A particularly strong wind event occurred in mid-May 2005 and caused an anomalous strong cooling off Cape Lopez and in the whole eastern tropical Atlantic Ocean. From the analysis of oceanic and atmospheric conditions during this particular event, it appears that anomalously strong boreal spring wind strengthening associated with anomalously strong Hadley cell activity prematurely triggered the onset of coastal rainfall in the northern Gulf of Guinea, making it the earliest over the 1998–2008 period. No similar atmospheric conditions were observed in May over the 1998–2008 period. It is also found that the anomalous oceanic and atmospheric conditions associated with the event exerted a strong influence on rainfall off northeast Brazil. This study highlights the different processes through which the wind power from the South Atlantic is brought to the ocean in the Gulf of Guinea and emphasizes the need to further document and monitor the South Atlantic region.

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