El Niño and Coral Reef Development in the Galápagos Islands

1991 ◽  
pp. 99-120 ◽  
Author(s):  
Mitchell W. Colgan
Keyword(s):  
Coral Reef ◽  
El Niño ◽  
El Nino ◽  
Galapagos Islands ◽  
Galápagos Islands ◽  
Reef Development

scholarly journals Effects of El Niño and La Niña Southern Oscillation events on the adrenocortical responses to stress in birds of the Galapagos Islands

2018 ◽  
Vol 259 ◽  
pp. 20-33 ◽  
Author(s):  
John C. Wingfield ◽  
Michaela Hau ◽  
P. Dee Boersma ◽  
L. Michael Romero ◽  
Nigella Hillgarth ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Galapagos Islands ◽  
La Niña ◽  
Galápagos Islands ◽  
La Nina ◽  
Adrenocortical Responses

Hydrographic variability west of the Galápagos islands during the 1982–1983 El Niño

1986 ◽  
Vol 17 (1-2) ◽  
pp. 137-162 ◽  
Author(s):  
S.P. Hayes ◽  
L.J. Mangum ◽  
R.T. Barber ◽  
A. Huyer ◽  
R.L. Smith
Keyword(s):  
El Niño ◽  
El Nino ◽  
Galapagos Islands ◽  
Galápagos Islands

scholarly journals The Effect of the Galápagos Islands on ENSO in Forced Ocean and Hybrid Coupled Models

2008 ◽  
Vol 38 (11) ◽  
pp. 2519-2534 ◽  
Author(s):  
Kristopher B. Karnauskas ◽  
Raghu Murtugudde ◽  
Antonio J. Busalacchi
Keyword(s):  
Wind Stress ◽  
Zonal Wind ◽  
El Niño ◽  
Time Scale ◽  
El Nino ◽  
Galapagos Islands ◽  
Galápagos Islands ◽  
Coupled Models ◽  
Zonal Wind Stress ◽  
Sst Anomaly

Abstract An ocean general circulation model (OGCM) of the tropical Pacific Ocean is used to examine the effects of the Galápagos Islands on the El Niño–Southern Oscillation (ENSO). First, a series of experiments is conducted using the OGCM in a forced context, whereby an idealized El Niño event may be examined in cases with and without the Galápagos Islands. In this setup, the sensitivity of the sea surface temperature (SST) anomaly response to the presence of the Galápagos Islands is examined. Second, with the OGCM coupled to the atmosphere via zonal wind stress, experiments are conducted with and without the Galápagos Islands to determine how the Galápagos Islands influence the time scale of ENSO. In the forced setup, the Galápagos Islands lead to a damped SST anomaly given an identical zonal wind stress perturbation. Mixed layer heat budget calculations implicate the entrainment mixing term, which confirms that the difference is due to the Galápagos Islands changing the background mean state, that is, the equatorial thermocline as diagnosed in a previous paper. In the hybrid coupled experiments, there is a clear shift in the power spectrum of SST anomalies in the eastern equatorial Pacific. Specifically, the Galápagos Islands lead to a shift in the ENSO time scale from a biennial to a quasi-quadrennial period. Mechanisms for the shift in ENSO time scale due to the Galápagos Islands are discussed in the context of well-known paradigms for the oscillatory nature of ENSO.

The Equatorial Current System West of the Galápagos Islands during the 2014–16 El Niño as Observed by Underwater Gliders

2021 ◽  
Vol 51 (1) ◽  
pp. 3-17 ◽  
Author(s):  
Daniel L. Rudnick ◽  
W. Brechner Owens ◽  
T. M. Shaun Johnston ◽  
Kristopher B. Karnauskas ◽  
Julie Jakoboski ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Current System ◽  
Galapagos Islands ◽  
Future Research ◽  
Model Assessment ◽  
Galápagos Islands ◽  
Underwater Gliders ◽  
Equatorial Current ◽  
The Mean

AbstractThe strong El Niño of 2014–16 was observed west of the Galápagos Islands through sustained deployment of underwater gliders. Three years of observations began in October 2013 and ended in October 2016, with observations at longitudes 93° and 95°W between latitudes 2°N and 2°S. In total, there were over 3000 glider-days of data, covering over 50 000 km with over 12 000 profiles. Coverage was superior closer to the Galápagos on 93°W, where gliders were equipped with sensors to measure velocity as well as temperature, salinity, and pressure. The repeated glider transects are analyzed to produce highly resolved mean sections and maps of observed variables as functions of time, latitude, and depth. The mean sections reveal the structure of the Equatorial Undercurrent (EUC), the South Equatorial Current, and the equatorial front. The mean fields are used to calculate potential vorticity Q and Richardson number Ri. Gradients in the mean are strong enough to make the sign of Q opposite to that of planetary vorticity and to have Ri near unity, suggestive of mixing. Temporal variability is dominated by the 2014–16 El Niño, with the arrival of depressed isopycnals documented in 2014 and 2015. Increases in eastward velocity advect anomalously salty water and are uncorrelated with warm temperatures and deep isopycnals. Thus, vertical advection is important to changes in heat, and horizontal advection is relevant to changes in salt. Implications of this work include possibilities for future research, model assessment and improvement, and sustained observations across the equatorial Pacific.

scholarly journals Transition to El Niño conditions in the eastern tropical Pacific in October 2015

2016 ◽  
Author(s):  
Lothar Stramma ◽  
Tim Fischer ◽  
Damian S. Grundle ◽  
Gerd Krahmann ◽  
Hermann W. Bange ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Galapagos Islands ◽  
Tropical Pacific ◽  
Nutrient Concentrations ◽  
Galápagos Islands ◽  
Eastern Tropical Pacific ◽  
Weak Current ◽  
Equatorial Undercurrent ◽  
Oxygen Concentrations

Abstract. A strong El Niño developed in early 2015. Measurements from a research cruise on the RV Sonne in October 2015 near the equator east of the Galapagos Islands and off the shelf of Peru, are used to investigate changes related to El Niño in the upper ocean in comparison with earlier cruises in this region. At the equator at 85°30’ W, a clear temperature increase leading to lower densities in the upper 350 m, despite a concurrent salinity increase from 40 to 350 m, developed in October 2015. Lower nutrient concentrations were also present in the upper 200 m, and higher oxygen concentrations were observed between 40 and 130 m. Except for the upper 60 m at 2°30’ S, however, there was no obvious increase in oxygen concentrations at sampling stations just north (1° N) and south (2°30’ S) of the equator at 85°30’ W. In the equatorial current field, the Equatorial Undercurrent (EUC) east of the Galapagos Islands almost disappeared in October 2015, with a transport of only 0.02 Sv in the equatorial channel between 1° S and 1° N, and a weak current band of 0.78 Sv located between 1° S and 2°30’ S. Such near-disappearances of the EUC in the eastern Pacific seem to occur only during strong El Niño events. Off the Peruvian shelf at ~9° S, where the sea surface temperature (SST) was elevated, upwelling was modified, and warm, saline and oxygen rich water was upwelled. Despite some weak El Niño related SST increase at ~12 to 16° S, the upwelling of cold, low salinity and oxygen-poor water was still active at the easternmost stations at three sections at ~12° S, ~14° S and ~16° S, while further west on these sections a transition to El Niño conditions appeared. Although in early 2015 the El Niño was strong and in October 2015 showed a clear El Niño influence on the EUC, in the eastern tropical Pacific the measurements only showed developing El Niño water mass distributions. In particular the oxygen distribution indicated the ongoing transition from ‘typical’ to El Niño conditions progressing southward along the Peruvian shelf.

scholarly journals Observed El Niño conditions in the eastern tropical Pacific in October 2015

Ocean Science ◽  
2016 ◽  
Vol 12 (4) ◽  
pp. 861-873 ◽  
Author(s):  
Lothar Stramma ◽  
Tim Fischer ◽  
Damian S. Grundle ◽  
Gerd Krahmann ◽  
Hermann W. Bange ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Galapagos Islands ◽  
Tropical Pacific ◽  
Nutrient Concentrations ◽  
Galápagos Islands ◽  
Eastern Tropical Pacific ◽  
Weak Current ◽  
Equatorial Undercurrent ◽  
Mass Distributions

Abstract. A strong El Niño developed in early 2015. Measurements from a research cruise on the R/V Sonne in October 2015 near the Equator east of the Galapagos Islands and off the shelf of Peru are used to investigate changes related to El Niño in the upper ocean in comparison with earlier cruises in this region. At the Equator at 85°30′ W, a clear temperature increase leading to lower densities in the upper 350 m had developed in October 2015, despite a concurrent salinity increase from 40 to 350 m. Lower nutrient concentrations were also present in the upper 200 m, and higher oxygen concentrations were observed between 40 and 130 m. In the equatorial current field, the Equatorial Undercurrent (EUC) east of the Galapagos Islands almost disappeared in October 2015, with a transport of only 0.02 Sv in the equatorial channel between 1° S and 1° N, and a weak current band of 0.78 Sv located between 1 and 2°30′ S. Such near-disappearances of the EUC in the eastern Pacific seem to occur only during strong El Niño events. Off the Peruvian shelf at  ∼  9° S, characteristics of upwelling were different as warm, saline, and oxygen-rich water was upwelled. At  ∼  12,  ∼  14, and  ∼  16° S, the upwelling of cold, low-salinity, and oxygen-poor water was still active at the easternmost stations of these three sections, while further west on these sections a transition to El Niño conditions appeared. Although from early 2015 the El Niño was strong, the October measurements in the eastern tropical Pacific only showed developing El Niño water mass distributions. In particular, the oxygen distribution indicated the ongoing transition from “typical” to El Niño conditions progressing southward along the Peruvian shelf.

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