Circulation in the Archipiélago de Colón (Galapagos Islands), November, 1993

Steger, John M.; Collins, Curtis A.; Chu, Peter C.

doi:10.1016/s0967-0645(98)00015-0

Cited by 18 publications

(9 citation statements)

References 12 publications

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“…Subsurface salinity maxima, thermostad thicknesses, and dissolved oxygen at 100 m identified these waters as originating in the Equatorial Undercurrent. The observed transport, 7-11 Sv, agreed well with the 6.6 Sv of transport of the Equatorial Undercurrent to the west of the Galápagos (92 • W) reported by Steger et al (1998).…”

Section: Discussionsupporting

confidence: 86%

“…Note that the numerical study of Montes et al (2010), indicates that most of the flow in the northern branch of the EUC moves northward to the north of the Galápagos and thence to the west in the northern branch of the South Equatorial Current (SEC). In the region of the Galápagos, the circulation is dominated by surfacing of the undercurrent along their western boundary and upwelling events (Steger et al, 1998;Lucero and Cornejo Rodriguez, 1990;Lucero, 2000;Karnauskas et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Structure of ocean circulation between the Galápagos Islands and Ecuador

2013

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Abstract. From 27 March to 5 April 2009, upper ocean velocities between the Galápagos Islands and Ecuador were measured using a vessel mounted ADCP. A region of possible strong cross-hemisphere exchange was observed immediately to the east of the Galápagos, where a shallow (200 m) 300 km wide northeastward surface flow transported 7–11 Sv. Underlying this strong northeastward surface current, a southward flowing undercurrent was observed which was at least 600 m thick, 100 km wide, and had an observed transport of 7–8 Sv. Next to the Ecuador coast, the shallow (< 200 m) Ecuador Coastal Current was observed to extend offshore 100 km with strongest flow, 0.33 m s−1, near the surface. Immediately to the west of the Ecuador Coastal Current, flow was directed eastward and southward into the beginnings of the Peru-Chile Countercurrent. The integral of the surface currents between the Galápagos and Ecuador agreed well with observed sea level differences. Although the correlation of the sea level differences with large scale climate indices (Niño3 and the Southern Oscillation Index) was significant, more than half of the sea level variability was not explained. Seasonal variability of the sea level difference indicated that sea level was 2 cm higher at the Galápagos during late winter and early spring, which could be associated with the pattern of northward surface flows observed by R/V Knorr.

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Section: Discussionsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Structure of ocean circulation between the Galápagos Islands and Ecuador

2013

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“…The cruise plan for the Iselin was designed for a related field program (i.e., not necessarily optimized for measuring the physical circulation), but the observations were unprecedented for the region in terms of spatial and temporal resolution. The velocity measurements reported in Steger et al (1998) showed an EUC core of 60-79 cm s 21 at ;75-m depth centered on 0.58S at all transects from 948 to 928W. As in Knauss (1966) and Leetmaa (1982), by 928W a weaker and deeper northern lobe of the EUC was clearly branching off from the main core, below 100-m depth and centered between the equator and 0.58N.…”

mentioning

confidence: 51%

“…After roughly another decade, just as the ADCP was becoming standard instrumentation on research and naval vessels, the Iron Enrichment Experiment (IRONEX) II during November 1993 gave Steger et al (1998) the opportunity to describe the physical circulation in the Galápagos Archipelago using data from hydrographic stations and ADCP mounted to the Columbus Iselin. The cruise plan for the Iselin was designed for a related field program (i.e., not necessarily optimized for measuring the physical circulation), but the observations were unprecedented for the region in terms of spatial and temporal resolution.…”

mentioning

confidence: 99%

Observing the Galápagos–EUC Interaction: Insights and Challenges

Karnauskas

Murtugudde

Busalacchi

2010

Journal of Physical Oceanography

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Although sustained observations yield a description of the mean equatorial current system from the western Pacific to the eastern terminus of the Tropical Atmosphere Ocean (TAO) array, a comprehensive observational dataset suitable for describing the structure and pathways of the Equatorial Undercurrent (EUC) east of 958W does not exist and therefore climate models are unconstrained in a region that plays a critical role in ocean-atmosphere coupling. Furthermore, ocean models suggest that the interaction between the EUC and the Galá pagos Islands (;928W) has a striking effect on the basic state and coupled variability of the tropical Pacific. To this end, the authors interpret historical measurements beginning with those made in conjunction with the discovery of the Pacific EUC in the 1950s, analyze velocity measurements from an equatorial TAO mooring at 858W, and analyze a new dataset from archived shipboard ADCP measurements. Together, the observations yield a possible composite description of the EUC structure and pathways in the eastern equatorial Pacific that may be useful for model validation and guiding future observation.

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“… Lindley and Barber [1998] provided evidence that this iron input supports nitrate uptake and elevated primary production in the plume. Although the specific source of island‐derived iron has not been identified, resuspension of iron‐rich sediment caused by interaction of flow with topography and tidal mixing, particularly in the Canal de Bolívar and in the adjacent bays to the north and south, has been suggested [ Steger et al , 1998]. Hydrothermal fluxes from the interior of western Galápagos volcanoes could also be an important source [cf.…”

Section: Discussionmentioning

confidence: 99%

Factors influencing the island‐mass effect of the Galápagos Archipelago

Palacios

2002

Geophysical Research Letters

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[1] Enhanced phytoplankton biomass in the wake of the Galápagos Islands is thought to result from an island-mass effect (IME) fueled by upwelling of the Equatorial Undercurrent (EUC) and by natural iron enrichment from the island platform. Annual means of five variables describing the thermocline, the pycnocline, and the availability of nitrate at the surface were derived from the World Ocean Atlas 1998 (WOA98). The first principal component of these variables explained 55.8% of the variance, corroborating that the Galápagos IME is associated with features of the EUC, mainly a shallow thermocline/pycnocline and its vertical spreading in the vicinity of the Galápagos. Regression analysis of SeaWiFSderived chlorophyll-a (chl) on the WOA98 variables indicated that the depth of the thermocline and nitrate availability explain 91.9% of the chl variance. A secondary IME of enhanced chl levels associated with the windsheltered area north of Isabela Island was evident in the residual variability.

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Circulation in the Archipiélago de Colón (Galapagos Islands), November, 1993

Cited by 18 publications

References 12 publications

Structure of ocean circulation between the Galápagos Islands and Ecuador

Structure of ocean circulation between the Galápagos Islands and Ecuador

Observing the Galápagos–EUC Interaction: Insights and Challenges

Factors influencing the island‐mass effect of the Galápagos Archipelago

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