ENSO and eddies on the southwest coast of Mexico

Zamudio, Luis; Leonardi, Alan P.; Meyers, Steven D.; O’Brien, James J.

doi:10.1029/2000gl011814

Cited by 56 publications

(52 citation statements)

References 9 publications

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“…Most likely the generation is driven by flow separation at the headlands of the West African coast, triggered by seasonality in the wind forcing. For the northeastern Pacific it has been shown that coastal trapped waves have an impact on the stability of coastal currents and hence eddy generation (Zamudio et al, 2001(Zamudio et al, , 2006(Zamudio et al, , 2007. Such eddy generation mechanisms may explain the high eddy generation in the TANWA found during phases of strongest boundary current velocities.…”

Section: Discussionmentioning

confidence: 95%

“…Different mechanisms for the generation of eddies in eastern boundary upwelling regions have been proposed (e.g., Liang et al, 2012). Barotropic and baroclinic instabilities of the near-coastal currents (Pantoja et al, 2012) triggered by, e.g., the passage of poleward propagating coastal trapped waves (Zamudio et al, 2001(Zamudio et al, , 2007, wind perturbations (Pares-Sierra et al, 1993), or interactions of the large-scale circulation with the bottom topography (Kurian et al, 2011) are the main processes identified for the eddy generation in eastern boundary upwelling regions. In the TANWA, the period of maximum eddy generation (June/July) is characterized by a strong near-surface boundary current, the MC (Lázaro et al, 2005) suggesting dynamic instabilities of the boundary current as an important generation mechanism.…”

Section: Seasonal Variability Of Eddy Generationmentioning

confidence: 99%

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Occurrence and characteristics of mesoscale eddies in the tropical northeastern Atlantic Ocean

2016

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Abstract. Coherent mesoscale features (referred to here as eddies) in the tropical northeastern Atlantic Ocean (between 12-22 • N and 15-26 • W) are examined and characterized. The eddies' surface signatures are investigated using 19 years of satellite-derived sea level anomaly (SLA) data. Two automated detection methods are applied, the geometrical method based on closed streamlines around eddy cores, and the Okubo-Weiß method based on the relation between vorticity and strain. Both methods give similar results. Mean eddy surface signatures of SLA, sea surface temperature (SST) and sea surface salinity (SSS) anomalies are obtained from composites of all snapshots around identified eddy cores. Anticyclones/cyclones are identified by an elevation/depression of SLA and enhanced/reduced SST and SSS in their cores. However, about 20 % of all anticyclonically rotating eddies show reduced SST and reduced SSS instead. These kind of eddies are classified as anticyclonic mode-water eddies (ACMEs). About 146 ± 4 eddies per year with a minimum lifetime of 7 days are identified (52 % cyclones, 39 % anticyclones, 9 % ACMEs) with rather similar mean radii of about 56 ± 12 km. Based on concurrent in situ temperature and salinity profiles (from Argo float, shipboard, and mooring data) taken inside of eddies, distinct mean vertical structures of the three eddy types are determined. Most eddies are generated preferentially in boreal summer and along the West African coast at three distinct coastal headland regions and carry South Atlantic Central Water supplied by the northward flow within the Mauretanian coastal current system. Westward eddy propagation (on average about 3.00 ± 2.15 km d −1 ) is confined to distinct zonal corridors with a small meridional deflection dependent on the eddy type (anticyclones -equatorward, cyclones -poleward, ACMEs -no deflection). Heat and salt fluxes out of the coastal region and across the Cape Verde Frontal Zone, which separates the shadow zone from the ventilated subtropical gyre, are calculated.

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Section: Discussionmentioning

confidence: 95%

Section: Seasonal Variability Of Eddy Generationmentioning

confidence: 99%

Occurrence and characteristics of mesoscale eddies in the tropical northeastern Atlantic Ocean

2016

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“…Umatani & Yamagata (1991), as well as Zamudio, Leonardi, Meyers & O'Brien (2001), showed that eddies can be generated even when the wind forcing is almost negligible. One question to consider is if the eddies can be obtained neglecting the wind forcing.…”

Section: Ocean Eddiesmentioning

confidence: 99%

The easternmost tropical Pacific. Part II: Seasonal and intraseasonal modes of atmospheric variability

Amador

Durán-Quesada

Rivera

et al. 2016

RBT

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This is Part II of a two-part review about climate and climate variability focused on the Eastern Tropical Pacific (ETP) and the Caribbean Sea (CS). Both parts are aimed at providing oceanographers, marine biologists, and other ocean scientists, a guiding base for ocean-atmosphere interaction processes affecting the CS, the ETP, and the waters of Isla del Coco. Isla del Coco National Park is a Costa Rican World Heritage site. Part I analyzed the mean fields for both basins and a larger region covering 25º S -35º N, 20º W -130º W. Here we focus on a smaller area (65º W -95º W, 0º -20º N), as a complement to Part 1. Incoming solar radiation and surface energy fluxes reveal the complex nature of the ETP and CS for convective activity and precipitation on seasonal and intraseasonal time scales. Both regions are relevant as sources of evaporation and the associated moisture transport processes. The American Monsoon System influences the climate and climate variability of the ETP and CS, however, the precise way systems affect regional precipitation and transport of moisture, within the Intra Americas Sea (IAS) are not clear. Although the Caribbean Low-Level Jet (CLLJ) is known to act as a conveyor belt for moisture transport, intraseasonal and seasonal modes of the CLLJ and their interactions with other IAS systems, have to be further investigated. Trans-isthmic jets, exert a variable seasonal wind stress force over the ocean surface co-generating regions of great marine productivity. Isolated convection, the seasonal migration of the Intertropical Convergence Zone, the hurricane season, the Mid-Summer Drought, the seasonal and intraseasonal behavior of low-level jets and their interactions with transients, and the southward incursion of cold fronts contribute to regional seasonal precipitation. Many large-scale systems, such as El Niño-Southern Oscillation, the Atlantic Multidecadal Oscillation and the Madden-Julian Oscillation (MJO, also influence the variability of precipitation by modulating regional features associated with convection and precipitation. Monthly tropical storm (TS) activity in the CS and ETP basins is restricted to the period May-November, with very few cases in December. The CS presents TS peak activity during August, as well as for the number of hurricanes and major hurricanes, in contrast to the ETP that shows the same features during September. Rev. Biol. Trop. 64 (Suppl. 1): S23-S57. Epub 2016 Febrary 01.Key words: Cocos Island, Isla del Coco, seasonal and intraseasonal variability modes, Madden-Julian Oscillation, Caribbean Low-Level Jet, Chocó Jet, trans-isthmic low-level jets, atmospheric rivers.The Intra Americas Sea (IAS) is defined here as a region comprising the Gulf of Mexico (GM), the Caribbean Sea (CS), the Easternmost Tropical Pacific (ETP) and embedded continental areas. The dominant rain-producing systems of this tropical region are primarily convective in nature, however, their origin may be very broad. Convection may be the result of land and sea breeze processes, di...

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“…They suggested that changes in eddy activity were likely generated by more strong wintertime cold surges into Central America during El Niñ o, but also noted that changes in the background sea level and the passage of strong coastally trapped Kelvin waves associated with ENSO could also modulate eddy activity. Zamudio et al (2001) found that during strong El Niñ o events, a narrow current associated with a downwelling Kelvin wave develops, which becomes unstable and breaks forming anticyclonic eddies that propagate away from the coast at ;188N. Anticyclonic eddies, with a deeper thermocline, were also more prevalent and stronger in the vicinity of Tehuantepec during the 1997 El Niñ o than during the 1998 and 1999 La Niñ a events, where the modulation in eddy generation was again linked to coastally trapped waves that were generated in the equatorial Pacific (Zamudio et al 2006).…”

mentioning

confidence: 99%

ENSO’s Impact on the Gap Wind Regions of the Eastern Tropical Pacific Ocean*

et al. 2012

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The recently released NCEP Climate Forecast System Reanalysis (CFSR) is used to examine the response to ENSO in the northeast tropical Pacific Ocean (NETP) during 1979-2009. The normally cool Pacific sea surface temperatures (SSTs) associated with wind jets through the gaps in the Central American mountains at Tehuantepec, Papagayo, and Panama are substantially warmer (colder) than the surrounding ocean during El Niñ o (La Niñ a) events. Ocean dynamics generate the ENSO-related SST anomalies in the gap wind regions as the surface fluxes damp the SSTs anomalies, while the Ekman heat transport is generally in quadrature with the anomalies. The ENSO-driven warming is associated with large-scale deepening of the thermocline; with the cold thermocline water at greater depths during El Niñ o in the NETP, it is less likely to be vertically mixed to the surface, particularly in the gap wind regions where the thermocline is normally very close to the surface. The thermocline deepening is enhanced to the south of the Costa Rica Dome in the Papagayo region, which contributes to the local ENSO-driven SST anomalies. The NETP thermocline changes are due to coastal Kelvin waves that initiate westward-propagating Rossby waves, and possibly ocean eddies, rather than by local Ekman pumping. These findings were confirmed with regional ocean model experiments: only integrations that included interannually varying ocean boundary conditions were able to simulate the thermocline deepening and localized warming in the NETP during El Niñ o events; the simulation with variable surface fluxes, but boundary conditions that repeated the seasonal cycle, did not.

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ENSO and eddies on the southwest coast of Mexico

Cited by 56 publications

References 9 publications

Occurrence and characteristics of mesoscale eddies in the tropical northeastern Atlantic Ocean

Occurrence and characteristics of mesoscale eddies in the tropical northeastern Atlantic Ocean

The easternmost tropical Pacific. Part II: Seasonal and intraseasonal modes of atmospheric variability

ENSO’s Impact on the Gap Wind Regions of the Eastern Tropical Pacific Ocean*

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