El Niño-Southern Oscillation sensitivity to cumulus entrainment in a coupled general circulation model

Kim, Dae Hyun; Jang, Yeon-Soo; Kim, Dong-Hoon; Kim, Young‐Ho; Watanabe, Masahiro; Jin, Fei‐Fei; Kug, Jong‐Seong

doi:10.1029/2011jd016526

Cited by 45 publications

(55 citation statements)

References 33 publications

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“…This may be because the model does not properly represent ocean eddy fluxes due to tropical instability waves (Jochum and Murtugudde 2006). The biases in the damping time (g 21 ) probably result from inadequacies in the parameterization of convection and clouds in the CM2.1 (Wittenberg et al 2006;Kim et al 2007Kim et al , 2011. For instance, Wittenberg et al (2006) showed that the convective response in the CM2.1 is shifted too far to the west, which may explain the westward shift in the CM2.1 damping time peaks as compared to the ECDA.…”

Section: A Model Results and Comparison With Ecdamentioning

confidence: 97%

Understanding Multidecadal Variability in ENSO Amplitude

Russell

Gnanadesikan

2014

Journal of Climate

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Sea surface temperatures (SSTs) in the tropical Pacific vary as a result of the coupling between ocean and atmosphere driven largely by El Niño-Southern Oscillation (ENSO). ENSO amplitude is known to vary on long time scales, which makes it difficult to quantify its response to climate change and constrain the physical processes that drive it. To characterize the long-period variability in ocean-atmosphere coupling strengths, a linear regression of local SST changes is applied to the 4000-yr GFDL Climate Model, version 2.1 (CM2.1) and the 500-yr GFDL CM2 with Modular Ocean Model version 4p1 (MOM4p1) at coarse resolution (CM2Mc) preindustrial control runs, while also comparing to the observationally constrained Ensemble Coupled Data Assimilation (ECDA) dataset. The models produce regression coefficients that vary widely on multidecadal time scales. These variations are strongly reflected in the long-period modulation of ocean stratification and surface precipitation. During high variance periods, when there is stronger stratification and precipitation in the central equatorial Pacific, the ocean's surface is less responsive to zonal wind stress perturbations, while the atmosphere is more responsive to SST perturbations. The mechanisms underlying this behavior are examined through an expansion of the linear regression equation to individual temperature tendency components. Long-term changes in ENSO amplitude are due to changes in both the oceanic response to the atmosphere, which is predominantly driven by regional changes in the advective and vertical diffusive heat tendencies, and the atmospheric response to the ocean.

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Section: A Model Results and Comparison With Ecdamentioning

confidence: 97%

Understanding Multidecadal Variability in ENSO Amplitude

Russell

Gnanadesikan

2014

Journal of Climate

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“…The Pacific climatological mean climate, particularly SSTs, has been known to influence the ENSO amplitude (An and Wang 2000;Yeh and Kirtman 2005;Kim et al 2011;Xiang et al 2013;Chung and Li 2013). Recently, Chung and Li demonstrated that the modulation of the ENSO amplitude is associated with decadal changes in the mean SST over the tropical Pacific, particularly through changes in the east-west gradient of the tropical Pacific SSTs and the precipitation changes associated with it.…”

Section: Introductionmentioning

confidence: 97%

“…Recently, Chung and Li demonstrated that the modulation of the ENSO amplitude is associated with decadal changes in the mean SST over the tropical Pacific, particularly through changes in the east-west gradient of the tropical Pacific SSTs and the precipitation changes associated with it. By using coupled model experiments with different parameter values for the convection scheme, Kim et al (2011) showed that the ENSO amplitude is sensitive to the mean precipitation over the eastern Pacific: increased mean precipitation over the eastern Pacific results in an increase in the ENSO amplitude. In their study, the increased mean precipitation over the eastern Pacific induced an eastward shift of the ENSO atmospheric component, particularly the zonal wind stress anomaly, that then resulted in stronger ENSO variability.…”

Section: Introductionmentioning

confidence: 99%

ENSO Amplitude Modulation Associated with the Mean SST Changes in the Tropical Central Pacific Induced by Atlantic Multidecadal Oscillation

Kang

Kucharski

2014

Journal of Climate

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The mechanism associated with the modulation of the El Niño-Southern Oscillation (ENSO) amplitude caused by the Atlantic multidecadal oscillation (AMO) is investigated by using long-term historical observational data and various types of models. The observational data for the period 1900-2013 show that the ENSO variability weakened during the positive phase of the AMO and strengthened in the negative phase. Such a relationship between the AMO and ENSO amplitude has been reported by a number of previous studies. In the present study the authors demonstrate that the weakening of the ENSO amplitude during the positive phase of the AMO is related to changes of the SST cooling in the eastern and central Pacific accompanied by the easterly wind stress anomalies in the equatorial central Pacific, which were reproduced reasonably well by coupled general circulation model (CGCM) simulations performed with the Atlantic Ocean SST nudged perpetually with the observed SST representing the positive phase of the AMO and the free integration in the other ocean basins. Using a hybrid coupled model, it was determined that the mechanism associated with the weakening of the ENSO amplitude is related to the westward shift and weakening of the ENSO zonal wind stress anomalies accompanied by the westward shift of precipitation anomalies associated with the relatively cold background mean SST over the central Pacific.

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“…According to Zhang (1993), the intensity of convection activity is weaker when the SST is lower. The climatological weak convective activity leads to weak atmospheric responses to SST forcing (Kim et al 2011;Jang et al 2013;Ham and Kug 2012;Kug et al 2012;Watanabe et al 2012). The weaker convective response to lower SST caused by chlorophyll reduces the Bjerkness feedback, and hence suppresses the role of the atmosphere on ENSO dynamics.…”

Section: Influence Of Marine Biology On the Enso Magnitudementioning

confidence: 99%

Impact of bio-physical feedbacks on the tropical climate in coupled and uncoupled GCMs

et al. 2013

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The bio-physical feedback process between the marine ecosystem and the tropical climate system is investigated using both an ocean circulation model and a fully-coupled ocean-atmosphere circulation model, which interact with a biogeochemical model. We found that the presence of chlorophyll can have significant impact on the characteristics of the El Niño-Southern Oscillation (ENSO), including its amplitude and asymmetry, as well as on the mean state. That is, chlorophyll generally increases mean sea surface temperature (SST) due to the direct biological heating. However, SST in the eastern equatorial Pacific decreases due to the stronger indirect dynamical response to the biological effects outweighing the direct thermal response. It is demonstrated that this biologicallyinduced SST cooling is intensified and conveyed to other tropical-ocean basins when atmosphere-ocean coupling is taken into account. It is also found that the presence of chlorophyll affects the magnitude of ENSO by two different mechanisms; one is an amplifying effect by the mean chlorophyll, which is associated with shoaling of the mean thermocline depth, and the other is a damping effect derived from the interactively-varying chlorophyll coupled with the physical model. The atmosphere-ocean coupling reduces the biologically-induced ENSO amplifying effect through the weakening of atmospheric feedback. Lastly, there is also a biological impact on ENSO which enhances the positive skewness. This skewness change is presumably caused by the phase dependency of thermocline feedback which affects the ENSO magnitude.

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El Niño-Southern Oscillation sensitivity to cumulus entrainment in a coupled general circulation model

Cited by 45 publications

References 33 publications

Understanding Multidecadal Variability in ENSO Amplitude

Understanding Multidecadal Variability in ENSO Amplitude

ENSO Amplitude Modulation Associated with the Mean SST Changes in the Tropical Central Pacific Induced by Atlantic Multidecadal Oscillation

Impact of bio-physical feedbacks on the tropical climate in coupled and uncoupled GCMs

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