Towards understanding the suppressed ENSO activity during mid-Holocene in PMIP2 and PMIP3 simulations

Chen, Lin; Zheng, Weipeng; Braconnot, Pascale

doi:10.1007/s00382-019-04637-z

Cited by 23 publications

(20 citation statements)

References 69 publications

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“…Nevertheless, due to model dependence of ENSO (Masson et al, ), our results should be treated with caution. Even though they are consistent with PMIP time slice simulations (e.g., the mid‐Holocene experiments) in terms of ENSO intensity, the underlying orbital forcing mechanisms are still difficult to be synthesized (e.g., An & Choi, ; Tian et al, ; Chen et al, ). It is ideal that glacial time scale transient experiments are reproduced using other climate models with ENSO forcing mechanisms diagnosed.…”

Section: Resultssupporting

confidence: 55%

Prominent Precession Band Variance in ENSO Intensity Over the Last 300,000 Years

Liu

Chen

et al. 2019

Geophysical Research Letters

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Three transient National Center for Atmospheric Research Community Climate System Model, version 3 model simulations were analyzed to study the responses of El Niño–Southern Oscillation (ENSO) and the equatorial Pacific annual cycle (AC) to external forcings over the last 300,000 years. The time‐varying boundary conditions of insolation, greenhouse gases, and continental ice sheets, accelerated by a factor of 100, were sequentially added in these simulations. The simulated ENSO and AC amplitudes change in phase, and both have pronounced precession band variance (~21,000 years). The precession‐modulated slow (orbital time scales) ENSO evolution is dominated linearly by the change of the coupled ocean‐atmosphere instability, notably the Ekman upwelling feedback and thermocline feedback. In contrast, the greenhouse gases and ice sheet forcings (~100,000‐year cycles) are opposed to each other as they influence ENSO variability through changes in AC amplitude via a common nonlinear frequency entrainment mechanism. The acceleration technique could dampen and delay the precession signals below the surface ocean associated with ENSO intensity.

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Section: Resultssupporting

confidence: 55%

Prominent Precession Band Variance in ENSO Intensity Over the Last 300,000 Years

Liu

Chen

et al. 2019

Geophysical Research Letters

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“…The mid-Holocene time-slice simulations of PMIP2 and PMIP3, all of which fixed climate forcing at 6,000 years ago (6ka), also showed suppressed ENSO variability in most of the models compared to the pre-industrial perpetual simulations (Braconnot et al, 2007;Chen et al, 2019b;Chiang et al, 2009;Zheng et al, 2008). The reduction of interannual variability in PMIP models was especially dominant over the equatorial central Pacific (An and Bong, 2018;Chen et al, 2019b).…”

Section: Introductionmentioning

confidence: 96%

Comparison of past and future simulations of ENSO in CMIP5/PMIP3 and CMIP6/PMIP4 models

Brown¹,

Brierley²,

An³

et al. 2020

Preprint

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Abstract. El Niño-Southern Oscillation (ENSO) is the strongest mode of interannual climate variability in the current climate, influencing ecosystems, agriculture and weather systems across the globe, but future projections of ENSO frequency and amplitude remain highly uncertain. A comparison of changes in ENSO in a range of past and future climate simulations can provide insights into the sensitivity of ENSO to changes in the mean state, including changes in the seasonality of incoming solar radiation, global average temperatures and spatial patterns of sea surface temperatures. As a comprehensive set of coupled model simulations are now available for both palaeoclimate time-slices (the Last Glacial Maximum, mid-Holocene and Last Interglacial) and idealised future warming scenarios (one percent per year CO2 increase, abrupt four times CO2 increase), this allows a detailed evaluation of ENSO changes in this wide range of climates. Such a comparison can assist in constraining uncertainty in future projections, providing insights into model agreement and the sensitivity of ENSO to a range of factors. The majority of models simulate a consistent weakening of ENSO activity in the Last Interglacial and mid-Holocene experiments, and there is an ensemble mean reduction of variability in the western equatorial Pacific in the Last Glacial Maximum experiments. Changes in global temperature produce a weaker precipitation response to ENSO in the cold Last Glacial Maximum experiments, and an enhanced precipitation response to ENSO in the warm increased CO2 experiments. No consistent relationship between changes in ENSO amplitude and annual cycle was identified across experiments.

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“…Later, Lu et al (2018) identified the ENSO linear periodicity, which is termed the Wyrtki index after a paper by Wyrtki (1975) (see Text S1 of supporting information for formulation). This method has been widely used in identifying the primary feedback processes that lead to the decadal changes in the ENSO characteristics (Lübbecke & McPhaden, 2014;An & Bong, 2015) and in evaluating the ENSO dynamics in the Climate Model Intercomparison Project simulations (Kim et al, 2014;Vijayeta & Dommenget, 2018) and Paleoclimate Model Intercomparison Project (An & Bong, 2018;Chen et al, 2019). These studies were limited by focusing on the changes in ENSO's amplitude and period, since this method was developed under the linear dynamic framework.…”

Section: Introductionmentioning

confidence: 99%

Untangling El Niño‐La Niña Asymmetries Using a Nonlinear Coupled Dynamic Index

Kim

2020

Geophysical Research Letters

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The linear recharge oscillator model for the El Niño–Southern Oscillation (ENSO) was expanded to a nonlinear model, thus allowing identification of a nonlinear dynamic ENSO index. This index was applied for a dynamic examination of the El Niño‐La Niña asymmetry. Here, the nonlinear physical processes including the nonlinear dynamical heating were implemented into the linear recharge oscillator model in the form of quadratic nonlinearity. This nonlinear recharge oscillator model revealed that nonlinear (linear) physical processes play a critical role in the long‐term ENSO skewness (amplitude) changes quantitatively. Particularly, the large part of the long‐term ENSO skewness change could be explained by the quadratic nonlinearity associated with the nonlinear ocean dynamical heating, which is closely related to change in mean thermocline. This research provides a unified framework to understand better the past‐present‐future ENSO changes by applying the interdecadal change dynamics on a low hierarchical level.

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Towards understanding the suppressed ENSO activity during mid-Holocene in PMIP2 and PMIP3 simulations

Cited by 23 publications

References 69 publications

Prominent Precession Band Variance in ENSO Intensity Over the Last 300,000 Years

Prominent Precession Band Variance in ENSO Intensity Over the Last 300,000 Years

Comparison of past and future simulations of ENSO in CMIP5/PMIP3 and CMIP6/PMIP4 models

Untangling El Niño‐La Niña Asymmetries Using a Nonlinear Coupled Dynamic Index

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