scholarly journals Evolution of Eastern Equatorial Pacific Seasonal and Interannual Variability in Response to Orbital Forcing During the Holocene and Eemian From Model Simulations

2018 ◽  
Vol 45 (18) ◽  
pp. 9843-9851 ◽  
Author(s):  
V. C. Khon ◽  
B. Schneider ◽  
M. Latif ◽  
W. Park ◽  
C. Wengel
Keyword(s):  
Interannual Variability ◽  
Equatorial Pacific ◽  
Orbital Forcing ◽  
Model Simulations ◽  
The Holocene ◽  
Seasonal And Interannual Variability ◽  
Eastern Equatorial Pacific

Seasonal and interannual variability of CO2 in the equatorial Pacific

2002 ◽  
Vol 49 (13-14) ◽  
pp. 2443-2469 ◽  
Author(s):  
Richard A Feely ◽  
Jacqueline Boutin ◽  
Catherine E Cosca ◽  
Yves Dandonneau ◽  
Jacqueline Etcheto ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Equatorial Pacific ◽  
Seasonal And Interannual Variability

scholarly journals Experimental Implementation of an Ensemble Adjustment Filter for an Intermediate ENSO Model

2007 ◽  
Vol 20 (18) ◽  
pp. 4638-4658 ◽  
Author(s):  
Alicia R. Karspeck ◽  
Jeffrey L. Anderson
Keyword(s):  
Interannual Variability ◽  
Wind Stress ◽  
Coupled Model ◽  
Equatorial Pacific ◽  
Thermocline Depth ◽  
Ensemble Size ◽  
Incomplete Observations ◽  
Eastern Equatorial Pacific ◽  
Experimental Implementation ◽  
Independent Observations

Abstract The assimilation of sea surface temperature (SST) anomalies into a coupled ocean–atmosphere model of the tropical Pacific is investigated using an ensemble adjustment Kalman filter (EAKF). The intermediate coupled model used here is the operational version of the Zebiak–Cane model, called LDEO5. The assimilation is applied as a means of estimating the true state of the system in the presence of incomplete observations of the state. In the first part of this study assimilation is performed under the “perfect model” assumption, where SST observations are synthetically derived from a trajectory of the model. The focus is on how and why changes in the filter parameters (ensemble size, covariance localization, and covariance inflation) affect the quality of the analysis. It is shown that isotropic covariance localization does not benefit the analysis even when a small number of ensemble members are used. These results suggest that destruction of the “balance” between variables caused by localization is more detrimental than spurious correlation due to small ensemble size. In the second part of this study the EAKF is used to assimilate an independent dataset of SST observations. The EAKF/Zebiak–Cane assimilation system is able to correctly estimate the phase and intensity of ENSO, as measured by the average SST anomaly in the eastern equatorial Pacific. A comparison of the analysis herein to independent wind stress and thermocline depth datasets suggests that even with the assimilation of only SST observations it is possible to reproduce over 70% of the interannual variability of thermocline depth in the eastern equatorial Pacific and off the coast of the Philippine Islands. The interannual variability of zonal wind stress in the central and western equatorial Pacific is also well correlated with independent observations (R > 0.75).

scholarly journals Response of the Equatorial Pacific Seasonal Cycle to Orbital Forcing

2015 ◽  
Vol 28 (23) ◽  
pp. 9258-9276 ◽  
Author(s):  
Michael P. Erb ◽  
Anthony J. Broccoli ◽  
Neal T. Graham ◽  
Amy C. Clement ◽  
Andrew T. Wittenberg ◽  
...  
Keyword(s):  
Seasonal Cycle ◽  
Equatorial Pacific ◽  
Climate Impacts ◽  
Ocean Dynamics ◽  
Orbital Forcing ◽  
Local Climate ◽  
Eastern Equatorial Pacific ◽  
Thermodynamic Effect ◽  
Western Equatorial Pacific ◽  
And Shifts

Abstract The response of the equatorial Pacific Ocean’s seasonal cycle to orbital forcing is explored using idealized simulations with a coupled atmosphere–ocean GCM in which eccentricity, obliquity, and the longitude of perihelion are altered while other boundary conditions are maintained at preindustrial levels. The importance of ocean dynamics in the climate response is investigated using additional simulations with a slab ocean version of the model. Precession is found to substantially influence the equatorial Pacific seasonal cycle through both thermodynamic and dynamic mechanisms, while changes in obliquity have only a small effect. In the precession experiments, western equatorial Pacific SSTs respond in a direct thermodynamic manner to changes in insolation, while the eastern equatorial Pacific is first affected by the propagation of thermocline temperature anomalies from the west. These thermocline signals result from zonal wind anomalies associated with changes in the strength of subtropical anticyclones and shifts in the regions of convection in the western equatorial Pacific. The redistribution of heat from these thermocline signals, aided by the direct thermodynamic effect of insolation anomalies, results in large changes to the strength and timing of the eastern equatorial Pacific seasonal cycle. A comparison of 10 CMIP5 mid-Holocene experiments, in which the primary forcing is due to precession, shows that this response is relatively robust across models. Because equatorial Pacific SST anomalies have local climate impacts as well as nonlocal impacts through teleconnections, these results may be important to understanding paleoclimate variations both inside and outside of the tropical Pacific.

scholarly journals The Influence of ENSO Flavors on Western North Pacific Tropical Cyclone Activity

2018 ◽  
Vol 31 (14) ◽  
pp. 5395-5416 ◽  
Author(s):  
Christina M. Patricola ◽  
Suzana J. Camargo ◽  
Philip J. Klotzbach ◽  
R. Saravanan ◽  
Ping Chang
Keyword(s):  
Tropical Cyclone ◽  
El Niño ◽  
North Pacific ◽  
Western North Pacific ◽  
El Nino ◽  
Equatorial Pacific ◽  
Atmospheric Variability ◽  
Central Pacific ◽  
Model Simulations ◽  
Eastern Equatorial Pacific

El Niño–Southern Oscillation (ENSO) is a major source of seasonal western North Pacific (WNP) tropical cyclone (TC) predictability. However, the spatial characteristics of ENSO have changed in recent decades, from warming more typically in the eastern equatorial Pacific during canonical or cold tongue El Niño to warming more typically in the central equatorial Pacific during noncanonical or warm pool El Niño. We investigated the response in basinwide WNP TC activity and spatial clustering of TC tracks to the location and magnitude of El Niño using observations, TC-permitting tropical channel model simulations, and a TC track clustering methodology. We found that simulated western North Pacific TC activity, including accumulated cyclone energy (ACE) and the number of typhoons and intense typhoons, is more effectively enhanced by sea surface temperature warming of the central, compared to the eastern, equatorial Pacific. El Niño also considerably influenced simulated TC tracks regionally, with a decrease in TCs that were generated near the Asian continent and an increase in clusters that were dominated by TC genesis in the southeastern WNP. This response corresponds with the spatial pattern of reduced vertical wind shear and is most effectively driven by central Pacific SST warming. Finally, internal atmospheric variability generated a substantial range in the simulated season total ACE (±25% of the median). However, extremely active WNP seasons were linked with El Niño, rather than internal atmospheric variability, in both observations and climate model simulations.

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