scholarly journals A decadally delayed response of the tropical Pacific to Atlantic multidecadal variability

2016 ◽  
Vol 43 (2) ◽  
pp. 784-792 ◽  
Author(s):  
Davide Zanchettin ◽  
Oliver Bothe ◽  
Hans F. Graf ◽  
Nour‐Eddine Omrani ◽  
Angelo Rubino ◽  
...  
Keyword(s):  
Tropical Pacific ◽  
Delayed Response ◽  
Atlantic Multidecadal Variability ◽  
Multidecadal Variability ◽  
The Tropical Pacific

scholarly journals Impacts of Atlantic Multidecadal Variability on the Tropical Pacific: a multi-model study

2021 ◽  
Author(s):  
Yohan Ruprich-Robert ◽  
Keyword(s):  
Tropical Pacific ◽  
Equatorial Pacific ◽  
Tropical Atlantic ◽  
Atlantic Multidecadal Variability ◽  
Multidecadal Variability ◽  
Upper Troposphere ◽  
Model Study ◽  
Model Set ◽  
Static Energy ◽  
The Tropical Pacific

<p>The Atlantic Multidecadal Variability (AMV) has been linked to the observed slowdown of global warming over 1998-2012 through its impact on the tropical Pacific. Given the global importance of tropical Pacific variability, better understanding this Atlantic-Pacific teleconnection is key for improving climate predictions, but the robustness and strength of this link is uncertain. Analysing a multi-model set of sensitivity experiments, we find that models differ by a factor 10 in simulating the amplitude of the Equatorial Pacific cooling response to observed AMV warming. The inter-model spread is mainly driven by different amounts of moist static energy injection from the tropical Atlantic surface into the upper troposphere. We reduce this inter-model uncertainty by analytically correcting models for their mean precipitation biases and we quantify that, following an observed 0.26ºC AMV warming, the equatorial Pacific cools by 0.16ºC with an inter-model standard deviation of 0.03ºC.</p>

scholarly journals Impacts of Atlantic multidecadal variability on the tropical Pacific: a multi-model study

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Yohan Ruprich-Robert ◽  
Eduardo Moreno-Chamarro ◽  
Xavier Levine ◽  
Alessio Bellucci ◽  
Christophe Cassou ◽  
...  
Keyword(s):  
Tropical Pacific ◽  
Equatorial Pacific ◽  
Tropical Atlantic ◽  
Atlantic Multidecadal Variability ◽  
Multidecadal Variability ◽  
Upper Troposphere ◽  
Model Study ◽  
Model Set ◽  
Static Energy ◽  
The Tropical Pacific

AbstractAtlantic multidecadal variability (AMV) has been linked to the observed slowdown of global warming over 1998–2012 through its impact on the tropical Pacific. Given the global importance of tropical Pacific variability, better understanding this Atlantic–Pacific teleconnection is key for improving climate predictions, but the robustness and strength of this link are uncertain. Analyzing a multi-model set of sensitivity experiments, we find that models differ by a factor of 10 in simulating the amplitude of the Equatorial Pacific cooling response to observed AMV warming. The inter-model spread is mainly driven by different amounts of moist static energy injection from the tropical Atlantic surface into the upper troposphere. We reduce this inter-model uncertainty by analytically correcting models for their mean precipitation biases and we quantify that, following an observed 0.26 °C AMV warming, the equatorial Pacific cools by 0.11 °C with an inter-model standard deviation of 0.03 °C.

Successive Modulation of ENSO to the Future Greenhouse Warming

2008 ◽  
Vol 21 (1) ◽  
pp. 3-21 ◽  
Author(s):  
Soon-Il An ◽  
Jong-Seong Kug ◽  
Yoo-Geun Ham ◽  
In-Sik Kang
Keyword(s):  
General Circulation ◽  
Southern Oscillation ◽  
General Circulation Models ◽  
Tropical Pacific ◽  
Greenhouse Warming ◽  
Delayed Response ◽  
Subsurface Temperature ◽  
Climate System Model ◽  
The Mean ◽  
The Tropical Pacific

Abstract The multidecadal modulation of the El Niño–Southern Oscillation (ENSO) due to greenhouse warming has been analyzed herein by means of diagnostics of Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) coupled general circulation models (CGCMs) and the eigenanalysis of a simplified version of an intermediate ENSO model. The response of the global-mean troposphere temperature to increasing greenhouse gases is more likely linear, while the amplitude and period of ENSO fluctuates in a multidecadal time scale. The climate system model outputs suggest that the multidecadal modulation of ENSO is related to the delayed response of the subsurface temperature in the tropical Pacific compared to the response time of the sea surface temperature (SST), which would lead a modulation of the vertical temperature gradient. Furthermore, an eigenanalysis considering only two parameters, the changes in the zonal contrast of the mean background SST and the changes in the vertical contrast between the mean surface and subsurface temperatures in the tropical Pacific, exhibits a good agreement with the CGCM outputs in terms of the multidecadal modulations of the ENSO amplitude and period. In particular, the change in the vertical contrast, that is, change in difference between the subsurface temperature and SST, turns out to be more influential on the ENSO modulation than changes in the mean SST itself.

Role of the Atmospheric and Oceanic Circulation in the Tropical Pacific SST Changes

2008 ◽  
Vol 21 (10) ◽  
pp. 2019-2034 ◽  
Author(s):  
Jingzhi Su ◽  
Huijun Wang ◽  
Haijun Yang ◽  
Helge Drange ◽  
Yongqi Gao ◽  
...  
Keyword(s):  
Tropical Pacific ◽  
Hadley Cell ◽  
Convective Precipitation ◽  
Delayed Response ◽  
Positive Temperature ◽  
Subsurface Temperature ◽  
Tropical Ocean ◽  
Temperature Anomalies ◽  
Sst Anomalies ◽  
The Tropical Pacific

Abstract A coupled climate model is used to explore the response of the tropical sea surface temperature (SST) to positive SST anomalies in the global extratropics. The main model results here are consistent with previous numerical studies. In response to prescribed SST anomalies in the extratropics, the tropical SSTs rise rapidly and reach a quasi-equilibrium state within several years, and the tropical subsurface temperatures show a slow response. The annual-mean Hadley cell, as well as the surface trades, are weakened. The weakened trades reduce the poleward Ekman transports in the tropical ocean and, furthermore, lead to anomalous positive convergences of heat transport, which is the main mechanism for maintaining the tropical Pacific SST warming. The process of an extratropical influence on the tropics is related to both the atmospheric and oceanic circulations. The intertropical convergence zone (ITCZ) moves southward and eastward in the Pacific, corresponding to a reduction of the Hadley circulation and Walker circulation. At the same time, convective precipitation anomalies are formed on the boundary of the climatological ITCZ, while the climatological mean convections centered in the Southeast Asia region are suppressed. The largely delayed response of the tropical subsurface temperature cannot be explained only by the strength change of the subtropical cells (STCs), but can be traced back to the slow changing of subsurface temperature in the extratropics. In the extratropical oceans, warming and freshening reduce the surface water density, and the outcropping lines of certain isopycnal layers are moved poleward. This poleward movement of outcropping lines can weaken the positive temperature anomalies, or even lead to negative anomalies, on given isopycnal layers. Displayed on time-dependent isopycnal layers, positive subsurface temperature anomalies are present only in the region after subduction, and are subsequently replaced by negative temperature anomalies in the deep tropics regions. The noticeable features of the density compensation of temperature and salinity indicate that diapycnal processes play an important role in the equatorward transport of the temperature and salinity anomalies from the midlatitude.

scholarly journals Are Simulated Megadroughts in the North American Southwest Forced?*

2014 ◽  
Vol 28 (1) ◽  
pp. 124-142 ◽  
Author(s):  
Sloan Coats ◽  
Jason E. Smerdon ◽  
Benjamin I. Cook ◽  
Richard Seager
Keyword(s):  
North American ◽  
General Circulation ◽  
Southern Oscillation ◽  
Tropical Pacific ◽  
American Southwest ◽  
Climate System Model ◽  
Multidecadal Variability ◽  
The North ◽  
North American Southwest ◽  
The Tropical Pacific

Abstract Multidecadal drought periods in the North American Southwest (25°–42.5°N, 125°–105°W), so-called megadroughts, are a prominent feature of the paleoclimate record over the last millennium (LM). Six forced transient simulations of the LM along with corresponding historical (1850–2005) and 500-yr preindustrial control runs from phase 5 of the Coupled Model Intercomparison Project (CMIP5) are analyzed to determine if atmosphere–ocean general circulation models (AOGCMs) are able to simulate droughts that are similar in persistence and severity to the megadroughts in the proxy-derived North American Drought Atlas. Megadroughts are found in each of the AOGCM simulations of the LM, although there are intermodel differences in the number, persistence, and severity of these features. Despite these differences, a common feature of the simulated megadroughts is that they are not forced by changes in the exogenous forcing conditions. Furthermore, only the Community Climate System Model (CCSM), version 4, simulation contains megadroughts that are consistently forced by cooler conditions in the tropical Pacific Ocean. These La Niña–like mean states are not accompanied by changes to the interannual variability of the El Niño–Southern Oscillation system and result from internal multidecadal variability of the tropical Pacific mean state, of which the CCSM has the largest magnitude of the analyzed simulations. Critically, the CCSM is also found to have a realistic teleconnection between the tropical Pacific and North America that is stationary on multidecadal time scales. Generally, models with some combination of a realistic and stationary teleconnection and large multidecadal variability in the tropical Pacific are found to have the highest incidence of megadroughts driven by the tropical Pacific boundary conditions.

Growing Coconut Palms in the Pacific Islands: Colliding Knowledge and Values

2020 ◽  
Author(s):  
Judith A. Bennett
Keyword(s):  
Pacific Islands ◽  
Social Values ◽  
Coconut Oil ◽  
Tropical Pacific ◽  
Experiential Knowledge ◽  
The West ◽  
Passive Resistance ◽  
The People ◽  
The Pacific ◽  
The Tropical Pacific

Coconuts provided commodities for the West in the form of coconut oil and copra. Once colonial governments established control of the tropical Pacific Islands, they needed revenue so urged European settlers to establish coconut plantations. For some decades most copra came from Indigenous growers. Administrations constantly urged the people to thin old groves and plant new ones like plantations, in grid patterns, regularly spaced and weeded. Local growers were instructed to collect all fallen coconuts for copra from their groves. For half a century, the administrations’ requirements met with Indigenous passive resistance. This paper examines the underlying reasons for this, elucidating Indigenous ecological and social values, based on experiential knowledge, knowledge that clashed with Western scientific values.

The tropical Pacific Oceanscape: Current issues, solutions and future possibilities.

2021 ◽  
Vol 166 ◽  
pp. 112181
Author(s):  
Michelle J. Devlin ◽  
Brett P. Lyons ◽  
Johanna E. Johnson ◽  
Jeremy M. Hills
Keyword(s):  
Tropical Pacific ◽  
The Tropical Pacific

scholarly journals A Link between the Hiatus in Global Warming and North American Drought

2015 ◽  
Vol 28 (9) ◽  
pp. 3834-3845 ◽  
Author(s):  
Thomas L. Delworth ◽  
Fanrong Zeng ◽  
Anthony Rosati ◽  
Gabriel A. Vecchi ◽  
Andrew T. Wittenberg
Keyword(s):  
Global Warming ◽  
North America ◽  
Surface Temperature ◽  
North American ◽  
Radiative Forcing ◽  
Tropical Pacific ◽  
Global Warming Hiatus ◽  
Warming Hiatus ◽  
The Impact ◽  
The Tropical Pacific

Abstract Portions of western North America have experienced prolonged drought over the last decade. This drought has occurred at the same time as the global warming hiatus—a decadal period with little increase in global mean surface temperature. Climate models and observational analyses are used to clarify the dual role of recent tropical Pacific changes in driving both the global warming hiatus and North American drought. When observed tropical Pacific wind stress anomalies are inserted into coupled models, the simulations produce persistent negative sea surface temperature anomalies in the eastern tropical Pacific, a hiatus in global warming, and drought over North America driven by SST-induced atmospheric circulation anomalies. In the simulations herein the tropical wind anomalies account for 92% of the simulated North American drought during the recent decade, with 8% from anthropogenic radiative forcing changes. This suggests that anthropogenic radiative forcing is not the dominant driver of the current drought, unless the wind changes themselves are driven by anthropogenic radiative forcing. The anomalous tropical winds could also originate from coupled interactions in the tropical Pacific or from forcing outside the tropical Pacific. The model experiments suggest that if the tropical winds were to return to climatological conditions, then the recent tendency toward North American drought would diminish. Alternatively, if the anomalous tropical winds were to persist, then the impact on North American drought would continue; however, the impact of the enhanced Pacific easterlies on global temperature diminishes after a decade or two due to a surface reemergence of warmer water that was initially subducted into the ocean interior.

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