Why Can Wind Delay the Shedding of Loop Current Eddies?

Chang, Yu Lin; Oey, Lie Yauw

doi:10.1175/2010jpo4460.1

Cited by 31 publications

(27 citation statements)

References 34 publications

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“…The seasonal cycle and intensity of the surface geostrophic velocities, the statistics associated with the variability and eddy shedding of the Loop Current, and the deep circulation are modeled accurately. The shedding of the Rings is influenced by the transport into the Gulf through the Yucatan Channel (Cardona and Bracco 2014;Chang and Oey 2010a) and by the winds (Chang and Oey 2010b), but it is not a deterministic process (Cardona and Bracco 2014, Lugo-Fernandez 2007, Sturges and Leben 2000. The runs presented here reproduce well the statistics of the observed fields, but the shedding events differ in LR and HR.…”

Section: Appendix Model Mean Circulation and Validationsupporting

confidence: 56%

Submesoscale circulation in the northern Gulf of Mexico: Surface processes and the impact of the freshwater river input

et al. 2016

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!The processes and instabilities occurring at the ocean surface in the northern Gulf of Mexico are investigated with a regional model at submesoscale-permitting horizontal grid resolution (i.e., HR with dx = 1.6 km) over a three-year period, from January 2010 to December 2012. A mesoscale-resolving, lower resolution run (LR, with dx = 5 km) is also considered for comparison. The HR run is obtained through two-way nesting within the LR run. In HR quantities such local Rossby number, horizontal divergence, vertical velocity, and strain rate are amplified in winter, when the mixed layer is deepest, as found in other basins. In the model configuration considered this amplification occurs in surface waters over the continental slope and off-shore but not over the shelf. Submesoscale structures consist of a mixture of fronts and eddies generated by frontogenesis and mixed layer instabilities, with elevated conversion rates of available potential energy (APE) into eddy kinetic energy (EKE). In all quantities a secondary maximum emerges during the summer season, when the mixed layer depth is shallowest, barely 15-20 m. The secondary peak extends to the coast and is due to the intense lateral density gradients created by the fresh water inflow from the Mississippi River system. Submesoscale structures in summer consist predominately of fronts, as observed in the aftermath of the 2010 Deepwater Horizon oil spill, and their secondary circulations are impeded due to the limited depth of the mixed layer. Freshwater river input is key to the submesoscale activity in summer but modulates it also in winter, as shown with a sensitivity run in which the riverine inflow is absent. Implications for transport studies in regions characterized by intense freshwater fluxes and for submesoscale parameterizations are discussed.

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Section: Appendix Model Mean Circulation and Validationsupporting

confidence: 56%

Submesoscale circulation in the northern Gulf of Mexico: Surface processes and the impact of the freshwater river input

et al. 2016

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“…These issues could be explored in future high-resolution regional experiments to assess the mechanisms that drive the plume seasonality. For instance, Chang and Oey (2010) found a decrease in the eddy shedding of the Loop Current due to the winds.…”

Section: Discussion and Concluding Remarksmentioning

confidence: 99%

Dynamics of an Equatorial River Plume: Theory and Numerical Experiments Applied to the Congo Plume Case

Vic

Berger²,

Tréguier

et al. 2014

Journal of Physical Oceanography

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The Congo River has the second largest rate of flow in the world and is mainly responsible for the broad tongue of low-salinity water that is observed in the Gulf of Guinea. Despite their importance, near-equatorial river plumes have not been studied as thoroughly as midlatitude plumes and their dynamics remain unclear. Using both theory and idealized numerical experiments that reproduce the major characteristics of the region, the authors have investigated the dynamics of the Congo River plume and examine its sensitivity to different forcing mechanisms. It is found that near-equatorial plumes are more likely to be surface trapped than midlatitude plumes, and the importance of the b effect in describing the strong offshore extent of the lowsalinity tongue during most of the year is demonstrated. It is shown that the buoyant plume constrained by the geomorphology is subject to the b pulling of nonlinear structures and wavelike equatorial dynamics. The wind is found to strengthen the intrinsic buoyancy-driven dynamics and impede the development of the coastal southward current, in coherence with observations.

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“…The LCEs have a diameter of 200-400 km and a vertical extension of 800-1000 m (Hamilton et al, 2015). They can detach and reattach from the LC several times before their final separation and subsequent migration to the west coast of the GoM occurs (Oey et al, 2005;Chang and Oey, 2010).…”

Section: Introductionmentioning

confidence: 99%

“…They suggest their theory applies to the flow at YCh, so neither instability nor topography are then required to produce a growing LC and LCE sheddings. Chang and Oey (2010, 2012 use these ideas to explain the LCE separation in their model. They find a strong positive correlation between LC extension, YCh vorticity and transport consistent with Pichevin-Nof's framework.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of Loop Current metrics and eddy detachments to different model configurations: The impact of topography and Caribbean perturbations

García-Jove¹,

Sheinbaum²,

Jouanno

2016

ATM

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RESUMENLa dinámica de la Corriente del Lazo (LC, por sus siglas en inglés) y la separación de su remolino anticiclónico (LCE, por sus siglas en inglés) son algunas de las características más importantes de la circulación en el Golfo de México (GoM, por sus siglas en inglés), así como índices comunes para evaluar la validez de las simulaciones numéricas. Utilizando un modelo numérico se estudian la sensibilidad de la LC y las separaciones de los LCE ante tres diferentes mecanismos considerados relevantes para su comportamiento: a) eliminación de las perturbaciones de vorticidad provenientes del Caribe que entran en el GoM; b) suavizado de la topografía, y c) supresión del cañón al este del Banco de Campeche.Los principales resultados de los experimentos de sensibilidad en comparación con un experimento de referencia, considerado el más realista, son los siguientes: a. La eliminación de los remolinos del Caribe reduce el número de separaciones de LCE, pero no son el mecanismo principal que desencadena las separaciones. Las inestabilidades localmente generadas sobre el Banco de Campeche del noreste y la extensión de la LC hacia el norte parecen ser los principales mecanismos que las controlan. b. El suavizado de la topografía genera una LC más ancha y menos intensa y además reduce los términos de intercambio de energía relacionados con inestabilidades del flujo. Sin embargo, el número de separaciones de LCE es similar al experimento de referencia. La extensión de la LC controla la liberación que, en este caso, tiende a ocurrir durante el verano-otoño, cuando dicha corriente está más extendida y el transporte de Yucatán se debilita abruptamente después de su máximo estacional. c. La supresión del cañón profundo al este del Banco de Campeche produce una extensión de la LC más estable y reduce el número de separaciones de LCE. El cañón parece desempeñar un papel importante en la intensificación de los ciclones generados sobre el frente este de la LC, que conducen finalmente a una separación de LCE. La distribución estacional de las separaciones de LCE en los experimentos no parece estar determinada por la intensificación de las inestabilidades barotrópicas y baroclínicas. En cambio, una condición necesaria pero no suficiente para liberar un LCE es que la LC se extienda más allá de los 24º N. Nuestros resultados sugieren que debe tenerse precaución al interpretar las estadísticas de la LC y las separaciones de LCE obtenidas a partir de una sola configuración numérica. ABSTRACTThe dynamics of the Loop Current (LC) and the release of its anticyclonic eddy (Loop Current eddy, LCE) are some of the most important features of the circulation in the Gulf of Mexico (GoM) and key aspects to gauge the validity of numerical simulations. Using a numerical model, we investigate the sensitivity of the LC and LCE detachments to three different mechanisms deemed to be relevant to their behavior: a) suppression doi: 10.20937/ATM.2016.29.03.05 Atmósfera 29(3), 235-265 (2016) 236 M. Garcia-Jove et al.of Caribbean vorticity perturba...

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Why Can Wind Delay the Shedding of Loop Current Eddies?

Cited by 31 publications

References 34 publications

Submesoscale circulation in the northern Gulf of Mexico: Surface processes and the impact of the freshwater river input

Submesoscale circulation in the northern Gulf of Mexico: Surface processes and the impact of the freshwater river input

Dynamics of an Equatorial River Plume: Theory and Numerical Experiments Applied to the Congo Plume Case

Sensitivity of Loop Current metrics and eddy detachments to different model configurations: The impact of topography and Caribbean perturbations

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