scholarly journals Contrasting Impacts of Three Extreme El Niños on Double ITCZs over the Eastern Pacific Ocean

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 424
Author(s):  
Yinlan Chen ◽  
Li Yan ◽  
Gen Li ◽  
Jianjun Xu ◽  
Jingchao Long ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
El Niño ◽  
El Nino ◽  
Intertropical Convergence Zone ◽  
Sea Surface ◽  
Eastern Pacific ◽  
Eastern Pacific Ocean ◽  
Symmetric Structure ◽  
Double Itcz ◽  
Sst Warming

In the recent four decades, there were three record-breaking El Niño events: 1982/1983, 1997/1998, and 2015/2016 events. A double intertropical convergence zone (ITCZ) pattern distinctively emerges over the eastern Pacific Ocean during boreal spring. Based on reanalysis (ERA-Interim) during 1979–2018, this study examines how these three extreme El Niños modulate such double ITCZs. The 1982/1983 and 1997/1998 El Niños moved both northern and southern ITCZs equatorward to form an individual and broad equatorial ITCZ. In contrast, the regulation of 2015/2016 El Niño was unique with a strengthened southern ITCZ to form a symmetric double-ITCZ. The above differences can be attributed to the different meridional structures of sea surface temperatures (SSTs). For the 1982/1983 and 1997/1998 El Niños, there was a meridionally symmetric structure of SST warming with a maximum at the equator. While for 2015/2016 El Niño, there was a meridionally symmetric structure of SST warming with a minimum at the equator.

Development of habitat prediction models to reduce by-catch of sailfish (Istiophorus platypterus) within the purse-seine fishery in the eastern Pacific Ocean

2015 ◽  
Vol 66 (7) ◽  
pp. 644 ◽  
Author(s):  
Raul O. Martinez-Rincon ◽  
Sofia Ortega-Garcia ◽  
Juan G. Vaca-Rodriguez ◽  
Shane P. Griffiths
Keyword(s):  
Pacific Ocean ◽  
El Niño ◽  
Coastal Waters ◽  
El Nino ◽  
Sea Surface ◽  
Eastern Pacific ◽  
Purse Seine ◽  
Eastern Pacific Ocean ◽  
Istiophorus Platypterus ◽  
By Catch

Sailfish (Istiophorus platypterus) is an important apex predator in neritic and oceanic pelagic ecosystems. The species is also a primary target of important catch-and-release sport fisheries that the support local economies of developing countries. However, commercial purse-seine fisheries that target tuna in the eastern Pacific Ocean (EPO) incidentally catch and discard large numbers of sailfish. Sailfish by-catch data recorded by scientific observers in the Mexican tuna purse-seine fleet in the EPO from 1998 to 2007 was used in generalised additive models (GAMs) to predict environmental and spatial preferences of sailfish. GAM predicted the highest sailfish catches to occur in coastal waters during El Niño events during late autumn and winter, with sea surface temperatures >26°C, with negative values of deviation in sea surface height (<–10cm), and low chlorophyll-a (<0.25mgm–3). GAM predicted that the catch probability for sailfish increased 1.8-fold during El Niño events in coastal waters and 1.5-fold under La Niña. However, the spatial distribution of sailfish remained largely unchanged during El Niño and La Niña events. Our models may be an additional fisheries management tool that may be used to support temporary spatial-temporal throughout the fishing season to reduce sailfish by-catch in the EPO.

scholarly journals In the Eastern Pacific Ocean, the "Blob" Overshadows El Niño

Eos ◽  
2016 ◽  
Vol 97 ◽  
Author(s):  
Sarah Stanley
Keyword(s):  
Pacific Ocean ◽  
West Coast ◽  
El Niño ◽  
El Nino ◽  
Ocean Modeling ◽  
Eastern Pacific ◽  
Eastern Pacific Ocean ◽  
Underwater Gliders

Underwater gliders and ocean modeling reveal unexpectedly weak El Niño effects on a major West Coast current.

scholarly journals Sensitivity of Tropical Tropospheric Temperature to Sea Surface Temperature Forcing*

2003 ◽  
Vol 16 (9) ◽  
pp. 1283-1301 ◽  
Author(s):  
Hui Su ◽  
J. David Neelin ◽  
Joyce E. Meyerson
Keyword(s):  
El Niño ◽  
El Nino ◽  
Sea Surface ◽  
Eastern Pacific ◽  
Substantial Contribution ◽  
Tropospheric Temperature ◽  
Temperature Anomalies ◽  
Sst Forcing ◽  
Sst Anomaly ◽  
Sst Anomalies

Abstract During El Niño, there are substantial tropospheric temperature anomalies across the entire tropical belt associated with the warming of sea surface temperatures (SSTs) in the central and eastern Pacific. The quasi-equilibrium tropical circulation model (QTCM) is used to investigate the mechanisms for tropical tropospheric temperature response to SST forcing. In both observations and model simulations, the tropical averaged tropospheric temperature anomaly 〈T̂′〉 is approximately linear with the tropical mean SST anomaly 〈T′s〉 for observed SST forcing. Regional SST anomaly experiments are used to estimate regional sensitivity measures and quantify the degree of nonlinearity. For instance, SST anomalies of 3°C in the central Pacific would give a nonlinear 〈T̂′〉 response about 15% greater than a linear fit to small SST anomaly experiments would predict, but for the maximum observed SST anomaly in this region the response differs by only 5% from linearity. Nonlinearity in 〈T̂′〉 response is modest even when local precipitation response is highly nonlinear. While temperature anomalies have large spatial scales, the main precipitation anomaly tends to be local to the SST anomaly regions. The tropical averaged precipitation anomalies 〈P′〉 do not necessarily have a simple relation to tropical averaged tropospheric temperature anomalies or SST forcing. The approximate linearity of the 〈T̂′〉 response is due to two factors: 1) the strong nonlinearities that occur locally tend to be associated with the transport terms, which become small in the large-area average; and 2) the dependence on temperature of the top-of-atmosphere and surface fluxes has only weak nonlinearity over the range of 〈T̂′〉 variations. Analytical approximations to the QTCM suggest that the direct impact of climatological SST, via flux terms, contributes modestly to regional variations in the sensitivity α of 〈T̂′〉 to 〈T′s〉. Wind speed has a fairly strong effect on α but tends to oppose the direct effect of SST since cold SST regions often have stronger climatological wind, which would yield larger slopes. A substantial contribution to regional variation in α comes from the different reaction of moisture to SST anomalies in precipitating and nonprecipitating regions. Although regions over climatologically warm water have a slightly higher sensitivity, subregions of El Niño SST anomalies even in the colder eastern Pacific contribute substantially to tropospheric temperature anomalies.

Role of Climate Feedback in El Niño–Like SST Response to Global Warming

2014 ◽  
Vol 27 (19) ◽  
pp. 7301-7318 ◽  
Author(s):  
Xiaoliang Song ◽  
Guang J. Zhang
Keyword(s):  
Global Warming ◽  
Water Vapor ◽  
El Niño ◽  
El Nino ◽  
Eastern Pacific ◽  
Climate Feedback ◽  
Central Pacific ◽  
Water Vapor Feedback ◽  
Sst Warming ◽  
The Mean

Abstract Under global warming from the doubling of CO2, the equatorial Pacific experiences an El Niño–like warming, as simulated by most global climate models. A new climate feedback and response analysis method (CFRAM) is applied to 10 years of hourly output of the slab ocean model (SOM) version of the NCAR Community Climate System Model, version 3.0, (CCSM3-SOM) to determine the processes responsible for this warming. Unlike the traditional surface heat budget analysis, the CFRAM can explicitly quantify the contributions of each radiative climate feedback and of each physical and dynamical process of a GCM to temperature changes. The mean bias in the sum of partial SST changes due to each feedback derived with CFRAM in the tropical Pacific is negligible (0.5%) compared to the mean SST change from the CCSM3-SOM simulations, with a spatial pattern correlation of 0.97 between the two. The analysis shows that the factors contributing to the El Niño–like SST warming in the central Pacific are different from those in the eastern Pacific. In the central Pacific, the largest contributor to El Niño–like SST warming is dynamical advection, followed by PBL diffusion, water vapor feedback, and surface evaporation. In contrast, in the eastern Pacific the dominant contributor to El Niño–like SST warming is cloud feedback, with water vapor feedback further amplifying the warming.

scholarly journals New Indices for Better Understanding ENSO by Incorporating Convection Sensitivity to Sea Surface Temperature

2020 ◽  
Vol 33 (16) ◽  
pp. 7045-7061 ◽  
Author(s):  
Ruihuang Xie ◽  
Mu Mu ◽  
Xianghui Fang
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
El Niño ◽  
El Nino ◽  
Longwave Radiation ◽  
High Impact ◽  
Sea Surface ◽  
Eastern Pacific ◽  
El Niño Events ◽  
El Nino Events

AbstractObserved outgoing longwave radiation (OLR) data indicate that convection is nonlinearly sensitive to sea surface temperature anomalies (SSTA) for background SSTs in the 25.25°–30.25°C high-impact range. In this study, we use that observed convection sensitivity to derive a proxy of the convective responses to SSTA only [referred to as fluctuations of the accumulated convection strength (FACT)]. FACT reproduces the pattern of the observed convection response to ENSO in the central and eastern Pacific, but underestimates the amplitude due to the exclusion of the effect of ENSO-induced atmospheric convergence anomalies on convection. We thus use FACT to define new indices (InFACT) of ENSO diversity that explicitly account for the nonlinear convection–SST sensitivity. The amplitude of InFACT allows us to easily classify El Niño events into weak, moderate, and strong types that markedly differ in terms of SSTA spatial patterns and their convective responses. La Niña events classified by InFACT display much less pattern diversity, and mostly differ through their amplitudes. Finally, our study supports some previous studies that the nonlinear SST–convection relation plays a strong role for the development of extreme El Niño events with the presence of high-impact SSTs and large convection anomalies in the equatorial eastern Pacific.

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