scholarly journals Slow-down in summer warming over Greenland in the past decade linked to central Pacific El Niño

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Shinji Matsumura ◽  
Koji Yamazaki ◽  
Kazuyoshi Suzuki
Keyword(s):  
El Niño ◽  
El Nino ◽  
Cyclonic Circulation ◽  
The Arctic ◽  
Central Pacific ◽  
Central Pacific El Niño ◽  
Atmospheric Teleconnection ◽  
El Niño Events ◽  
The Tropics ◽  
El Nino Events

AbstractGreenland warming and ice loss have slowed down since the early 2010s, in contrast to the rest of the Arctic region. Both natural variability and anthropogenic forcing contribute to recent Greenland warming by reducing cloud cover and surface albedo, yet most climate models are unable to reasonably simulate the unforced natural variability. Here we show that a simplified atmospheric circulation model successfully simulates an atmospheric teleconnection from the tropics towards Greenland, which accounts for Greenland cooling through an intensified cyclonic circulation. Synthesis from observational analysis and model experiments indicate that over the last decade, more central Pacific El Niño events than canonical El Niño events have generated the atmospheric teleconnection by shifting the tropical rainfall zone poleward, which led to an intensified cyclonic circulation over Greenland. The intensified cyclonic circulation further extends into the Arctic Ocean in observations, whereas the model does not show a direct remote forcing from the tropics, implying the contribution of an indirect atmospheric forcing. We conclude that the frequent occurrence of central Pacific El Niño events has played a key role in the slow-down of Greenland warming and possibly Arctic sea-ice loss.

scholarly journals ENSO flavors in a tree-ring δ<sup>18</sup>O record of <i>Tectona grandis</i> from Indonesia

2015 ◽  
Vol 11 (10) ◽  
pp. 1325-1333 ◽  
Author(s):  
K. Schollaen ◽  
C. Karamperidou ◽  
P. Krusic ◽  
E. Cook ◽  
G. Helle
Keyword(s):  
Tree Ring ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Central Pacific ◽  
Central Pacific El Niño ◽  
Enso Events ◽  
Proxy Records ◽  
El Niño Events ◽  
El Nino Events

Abstract. Indonesia's climate is dominated by the equatorial monsoon system, and has been linked to El Niño-Southern Oscillation (ENSO) events that often result in extensive droughts and floods over the Indonesian archipelago. In this study we investigate ENSO-related signals in a tree-ring δ18O record (1900–2007) of Javanese teak. Our results reveal a clear influence of Warm Pool (central Pacific) El Niño events on Javanese tree-ring δ18O, and no clear signal of Cold Tongue (eastern Pacific) El Niño events. These results are consistent with the distinct impacts of the two ENSO flavors on Javanese precipitation, and illustrate the importance of considering ENSO flavors when interpreting palaeoclimate proxy records in the tropics, as well as the potential of palaeoclimate proxy records from appropriately selected tropical regions for reconstructing past variability of. ENSO flavors.

Toward a record of Central Pacific El Niño events since 1880

2014 ◽  
Vol 119 (1-2) ◽  
pp. 379-389 ◽  
Author(s):  
M. Pascolini-Campbell ◽  
D. Zanchettin ◽  
O. Bothe ◽  
C. Timmreck ◽  
D. Matei ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Central Pacific ◽  
Central Pacific El Niño ◽  
El Niño Events ◽  
El Nino Events

scholarly journals Long Island Sound Temperature Variability and its Associations with the Ridge-trough Dipole and Tropical Modes of Sea Surface Temperature Variability

2018 ◽  
Author(s):  
Justin A. Schulte ◽  
Sukyoung Lee
Keyword(s):  
Water Temperature ◽  
El Niño ◽  
El Nino ◽  
Temperature Variability ◽  
Central Pacific ◽  
Central Pacific El Niño ◽  
El Niño Events ◽  
Cold Events ◽  
Dipole Pattern ◽  
El Nino Events

Abstract. Possible mechanisms behind the longevity of intense Long Island Sound (LIS) water temperature events are examined using an event-based approach. By decomposing a LIS surface water temperature time series into negative and positive events, it is revealed that the most intense LIS water temperature event in the 1979–2013 period occurred around 2012, coinciding with the 2012 ocean heat wave across the mid-Atlantic Bight. The LIS events are related to a ridge-trough dipole pattern whose strength and evolution can be measured using a dipole index. The dipole index was shown to be strongly correlated with LIS water temperature anomalies, explaining close to 64 % of cool-season LIS water temperature variability. Consistently, a major dipole pattern event coincided with the intense 2012 LIS warm event. A composite analysis revealed that long-lived intense LIS water temperature events are associated with tropical sea surface temperature (SST) patterns. The onset and mature phases of LIS cold events were shown to coincide with central Pacific El Niño events, whereas the termination of LIS cold events was shown to possibly coincide with canonical El Niño events or El Niño events that are a mixture of eastern and central Pacific El Niño flavors. The mature phase of LIS warm events was shown to be associated with negative SST anomalies across the central equatorial Pacific, though the results were not found to be robust. The dipole pattern was also shown to be related to tropical SST patterns and fluctuations in central Pacific SST anomalies were shown to evolve coherently with the dipole pattern and the strongly related East Pacific/North Pacific pattern on decadal time scales. The results from this study have important implications for seasonal and decadal prediction of the LIS thermal system.

scholarly journals Influence of Arctic sea-ice variability on Pacific trade winds

2020 ◽  
Vol 117 (6) ◽  
pp. 2824-2834 ◽  
Author(s):  
Charles F. Kennel ◽  
Elena Yulaeva
Keyword(s):  
Sea Ice ◽  
El Niño ◽  
El Nino ◽  
Arctic Sea Ice ◽  
Central Pacific ◽  
Central Pacific El Niño ◽  
Trade Winds ◽  
Upper Troposphere ◽  
El Niño Events ◽  
El Nino Events

A conceptual model connecting seasonal loss of Arctic sea ice to midlatitude extreme weather events is applied to the 21st-century intensification of Central Pacific trade winds, emergence of Central Pacific El Nino events, and weakening of the North Pacific Aleutian Low Circulation. According to the model, Arctic Ocean warming following the summer sea-ice melt drives vertical convection that perturbs the upper troposphere. Static stability calculations show that upward convection occurs in annual 40- to 45-d episodes over the seasonally ice-free areas of the Beaufort-to-Kara Sea arc. The episodes generate planetary waves and higher-frequency wave trains that transport momentum and heat southward in the upper troposphere. Regression of upper tropospheric circulation data on September sea-ice area indicates that convection episodes produce wave-mediated teleconnections between the maximum ice-loss region north of the Siberian Arctic coast and the Intertropical Convergence Zone (ITCZ). These teleconnections generate oppositely directed trade-wind anomalies in the Central and Eastern Pacific during boreal winter. The interaction of upper troposphere waves with the ITCZ air–sea column may also trigger Central Pacific El Nino events. Finally, waves reflected northward from the ITCZ air column and/or generated by triggered El Nino events may be responsible for the late winter weakening of the Aleutian Low Circulation in recent years.

scholarly journals The North Equatorial Countercurrent East of the Dateline, Its Variations, and Its Relationship to the El Niño Event

2021 ◽  
Vol 9 (10) ◽  
pp. 1041
Author(s):  
Yusuf Jati Wijaya ◽  
Ulung Jantama Wisha ◽  
Yukiharu Hisaki
Keyword(s):  
El Niño ◽  
El Nino ◽  
Thermocline Depth ◽  
Central Pacific ◽  
Ocean Reanalysis ◽  
Central Pacific El Niño ◽  
The North ◽  
El Niño Events ◽  
Ep El Niño ◽  
El Nino Events

Using forty years (1978–2017) of Ocean Reanalysis System 4 (ORAS4) dataset, the purpose of this study is to investigate the fluctuation of the North Equatorial Countercurrent (NECC) to the east of the dateline in relation to the presence of three kinds of El Niño events. From spring (MAM) through summer (JJA), we found that the NECC was stronger during the Eastern Pacific El Niño (EP El Niño) and the MIX El Niño than during the Central Pacific El Niño (CP El Niño). When it comes to winter (DJF), on the other hand, the NECC was stronger during the CP and MIX El Niño and weaker during the EP El Niño. This NECC variability was affected by the fluctuations of thermocline depth near the equatorial Pacific. Moreover, we also found that the seasonal southward shift of the NECC occurred between winter and spring, but the shift was absent during the CP and MIX El Niño events. This meridional shift was strongly affected by the local wind stress.

scholarly journals ENSO flavors in a tree-ring δ<sup>18</sup>O record of <i>Tectona grandis</i> from Indonesia

2014 ◽  
Vol 10 (5) ◽  
pp. 3965-3987 ◽  
Author(s):  
K. Schollaen ◽  
C. Karamperidou ◽  
P. J. Krusic ◽  
E. R. Cook ◽  
G. Helle
Keyword(s):  
Tree Ring ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Tectona Grandis ◽  
Central Pacific ◽  
Central Pacific El Niño ◽  
Enso Events ◽  
El Niño Events ◽  
El Nino Events

Abstract. Indonesia's climate is dominated by the equatorial monsoon system, and has been linked to El Niño–Southern Oscillation (ENSO) events that often result in extensive droughts and floods over the Indonesian archipelago. In this study we investigate ENSO-related signals in a tree-ring δ18O record (1900–2007) of Javanese teak. Our results reveal a clear influence of Warm Pool (central Pacific) El Niño events on Javanese tree-ring δ18O, and no clear signal of Cold Tongue (eastern Pacific) El Niño events. These results are consistent with the distinct impacts of the two ENSO flavors on Javanese precipitation, and illustrate the importance of considering ENSO flavors when interpreting palaeoclimate proxy records in the tropics.

scholarly journals Linking Emergence of the Central Pacific El Niño to the Atlantic Multidecadal Oscillation

2015 ◽  
Vol 28 (2) ◽  
pp. 651-662 ◽  
Author(s):  
Jin-Yi Yu ◽  
Pei-ken Kao ◽  
Houk Paek ◽  
Huang-Hsiung Hsu ◽  
Chih-wen Hung ◽  
...  
Keyword(s):  
Phase Change ◽  
El Niño ◽  
El Nino ◽  
Atlantic Multidecadal Oscillation ◽  
Central Pacific ◽  
Central Pacific El Niño ◽  
Ocean Response ◽  
El Niño Events ◽  
Numerical Model Experiments ◽  
El Nino Events

Abstract The ocean–atmosphere coupling in the northeastern subtropical Pacific is dominated by a Pacific meridional mode (PMM), which spans between the extratropical and tropical Pacific and plays an important role in connecting extratropical climate variability to the occurrence of El Niño. Analyses of observational data and numerical model experiments were conducted to demonstrate that the PMM (and the subtropical Pacific coupling) experienced a rapid strengthening in the early 1990s and that this strengthening is related to an intensification of the subtropical Pacific high caused by a phase change of the Atlantic multidecadal oscillation (AMO). This PMM strengthening favored the development of more central Pacific (CP)-type El Niño events. The recent shift from more conventional eastern Pacific (EP) to more CP-type El Niño events can thus be at least partly understood as a Pacific Ocean response to a phase change in the AMO.

scholarly journals Higher frequency of Central Pacific El Niño events in recent decades relative to past centuries

2019 ◽  
Vol 12 (6) ◽  
pp. 450-455 ◽  
Author(s):  
Mandy B. Freund ◽  
Benjamin J. Henley ◽  
David J. Karoly ◽  
Helen V. McGregor ◽  
Nerilie J. Abram ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Central Pacific ◽  
Central Pacific El Niño ◽  
El Niño Events ◽  
El Nino Events

scholarly journals Long Island Sound temperature variability and its associations with the ridge–trough dipole and tropical modes of sea surface temperature variability

Ocean Science ◽  
2019 ◽  
Vol 15 (1) ◽  
pp. 161-178 ◽  
Author(s):  
Justin A. Schulte ◽  
Sukyoung Lee
Keyword(s):  
Water Temperature ◽  
El Niño ◽  
El Nino ◽  
Temperature Variability ◽  
Central Pacific ◽  
Central Pacific El Niño ◽  
El Niño Events ◽  
Cold Events ◽  
Dipole Pattern ◽  
El Nino Events

Abstract. Possible mechanisms behind the longevity of intense Long Island Sound (LIS) water temperature events are examined using an event-based approach. By decomposing an LIS surface water temperature time series into negative and positive events, it is revealed that the most intense LIS water temperature event in the 1979–2013 period occurred around 2012, coinciding with the 2012 ocean heat wave across the Mid-Atlantic Bight. The LIS events are related to a ridge–trough dipole pattern whose strength and evolution can be determined using a dipole index. The dipole index was shown to be strongly correlated with LIS water temperature anomalies, explaining close to 64 % of cool-season LIS water temperature variability. Consistently, a major dipole pattern event coincided with the intense 2012 LIS warm event. A composite analysis revealed that long-lived intense LIS water temperature events are associated with tropical sea surface temperature (SST) patterns. The onset and mature phases of LIS cold events were shown to coincide with central Pacific El Niño events, whereas the termination of LIS cold events was shown to possibly coincide with canonical El Niño events or El Niño events that are a mixture of eastern and central Pacific El Niño flavors. The mature phase of LIS warm events was shown to be associated with negative SST anomalies across the central equatorial Pacific, though the results were not found to be robust. The dipole pattern was also shown to be related to tropical SST patterns, and fluctuations in central Pacific SST anomalies were shown to evolve coherently with the dipole pattern and the strongly related East Pacific–North Pacific pattern on decadal timescales. The results from this study have important implications for seasonal and decadal prediction of the LIS thermal system.

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