Amazon and Orinoco River Plumes and NBC Rings: Bystanders or Participants in Hurricane Events?

Ffield, Amy

doi:10.1175/jcli3985.1

Cited by 86 publications

(115 citation statements)

References 43 publications

(40 reference statements)

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“…Past studies have suggested a potential role of BLs in TC-induced SST cooling (19) and TC intensification (20)(21)(22). However, the impact of BLs on TC intensification has not been definitively demonstrated or quantified.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Ocean barrier layers’ effect on tropical cyclone intensification

Balaguru

Chang

Saravanan

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

252

221

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Improving a tropical cyclone's forecast and mitigating its destructive potential requires knowledge of various environmental factors that influence the cyclone's path and intensity. Herein, using a combination of observations and model simulations, we systematically demonstrate that tropical cyclone intensification is significantly affected by salinity-induced barrier layers, which are "quasi-permanent" features in the upper tropical oceans. When tropical cyclones pass over regions with barrier layers, the increased stratification and stability within the layer reduce storm-induced vertical mixing and sea surface temperature cooling. This causes an increase in enthalpy flux from the ocean to the atmosphere and, consequently, an intensification of tropical cyclones. On average, the tropical cyclone intensification rate is nearly 50% higher over regions with barrier layers, compared to regions without. Our finding, which underscores the importance of observing not only the upper-ocean thermal structure but also the salinity structure in deep tropical barrier layer regions, may be a key to more skillful predictions of tropical cyclone intensities through improved ocean state estimates and simulations of barrier layer processes. As the hydrological cycle responds to global warming, any associated changes in the barrier layer distribution must be considered in projecting future tropical cyclone activity.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Ocean barrier layers’ effect on tropical cyclone intensification

Balaguru

Chang

Saravanan

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

252

221

View full text Add to dashboard Cite

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“…As the BL plays a role in trapping the heat within the upper ocean layer, it may also affect the Atlantic hurricane activity (Ffield, 2007;Vizy and Cook, 2009). The Amazon plume, which extends into the Caribbean Sea, has relatively high SSTs.…”

Section: Introductionmentioning

confidence: 99%

The Barrier Layer of the Atlantic warm pool: Formation mechanism and influence on the mean climate

Balaguru

Chang

Saravanan

et al. 2012

Tellus A: Dynamic Meteorology and Oceanography

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A B S T R A C T Many coupled general circulation models (CGCMs) tend to overestimate the salinity in the Atlantic warm pool or the Northwestern Tropical Atlantic (NWTA) and underestimate the surface salinity in the subtropical salinity maxima region. Most of these models also suffer from a sea-surface temperature (SST) bias in the NWTA region, leading to suggestions that the upper ocean salinity stratification may need to be improved in order to improve the barrier layer (BL) simulations and thus the SST through BL-SST-intertropical convergence zone feedbacks. In the present study, we use a CGCM to perform a set of idealised numerical experiments to test and understand the sensitivity of the BL and consequently SST in the NWTA region to freshwater flux and hence the upper ocean salinity stratification. We find that the BL of the NWTA is sensitive to upper ocean salinity changes in the Amazon river discharge region and the subtropical salinity maxima region. The BL phenomenon is further manifested by the formation of winter temperature inversions in our model simulations, the maximum magnitude of inversions being about 0.2 8C. The atmospheric response causes a statistically significant reduction of mean precipitation and SST in the equatorial Atlantic region and helps improve the respective biases by 10Á15%. In the region of improved BL simulation, the SST change is positive and in the right direction of bias correction, albeit weak.

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“…Este último influi na distribuição de salinidade nas águas tropicais e, de forma indireta, na variabilidade das propriedades termodinâmicas em larga extensão sobre o oceano Atlântico tropical. Influencia também no estoque de nutrientes na plataforma continental, porém algumas evidências quantitativas de águas amazônicas reconhecem o relativo suprimento de nutrientes a partir do rio e também de fontes advectivas (Gibbs, 1972;Milliman e Boyle, 1975;Sprintall e Tomczac, 1992;Pailler et al, 1999;Silva et al, 2005a,b;Silva et al, 2007a,b;Ffield, 2007;Subramaniam et al, 2008). Calef e Grice (1967) mostram que as lentes de águas amazônicas afetam a diversidade e a quantidade de certas comunidades planctônicas ao largo da foz do rio Amazonas.…”

Section: Introductionunclassified

Observações hidrológicas e resultados de modelagem no espalhamento sazonal e espacial da pluma de água Amazônica

et al. 2009

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ResumoNeste estudo são apresentadas as análises espaciais e temporais dos dados sinóticos coletados durante quatro campanhas oceanográficas do programa "REVIZEE/SCORE-N" realizadas em março-abril de 1995, outubro-novembro de 1997, abrilmaio de 1999 e agosto-setembro de 2001. Em complemento às análises dos dados hidrológicos, foram utilizados resultados do modelo numérico CLIPPER -Experimento ATL6 (1/6 deg.). A ênfase deste artigo é avaliar o deslocamento sazonal e espacial da pluma de água Amazônica nas regiões localizadas à sudoeste, noroeste e em frente à foz do rio Amazonas. Dados hidrológicos e resultados do modelo demonstram que durante os meses de março-maio a pluma do rio Amazonas move-se para sudoeste, ao longo da costa norte brasileiro, tendendo a diminuir o deslocamento da pluma para sudoeste durante os meses de agosto-setembro. De outubro a novembro, não foi observado ou registrado o deslocamento da pluma para sudoeste. Resultados do modelo revelam anéis gerados pela retroflexão da Corrente Norte do Brasil (CNB) em torno de 7º N, e também a influência de água proveniente do rio Amazonas em volta desses anéis durante o mês de agosto.PalavRas-chave: Pluma do rio Amazonas; anéis; Corrente Norte do Brasil; modelo Atlântico; dados do REVIZEE. Hydrological observations and modeling results of the seasonal and spatial spread of the Amazonian water plume abstRactIn this study, we present surface synoptic data collected during four oceanographic cruises undertaken in March-April 1995, October-November 1997, April-May 1999 and August-September 2001 in the Brazilian Program "REVIZEE/SCORE-NO" and a combination of model results (1/6 deg.). The emphasis of this paper is to point out the monthly changes on the spreading of the Amazon plume over the external Amazon shelf area and the eastern region of the Amazon River. Hydrographic data and model results demonstrated that during March-May, the Amazon plume moved southwestward along the northern coast of Brazil, decreasing during August-September; but this was not observed during October-November. Model results revealed ring signatures shedding from the North Brazil Current (NBC). Results also showed that during August the Amazon plume encircling the NBC retroflection was around 7º N.

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Amazon and Orinoco River Plumes and NBC Rings: Bystanders or Participants in Hurricane Events?

Cited by 86 publications

References 43 publications

Ocean barrier layers’ effect on tropical cyclone intensification

Ocean barrier layers’ effect on tropical cyclone intensification

The Barrier Layer of the Atlantic warm pool: Formation mechanism and influence on the mean climate

Observações hidrológicas e resultados de modelagem no espalhamento sazonal e espacial da pluma de água Amazônica

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