Decadal Modulation of ENSO Spring Persistence Barrier by Thermal Damping Processes in the Observation

Fang, Xiaodong; Zheng, Fei; Liu, Zheng‐Yu; Zhu, Jiang

doi:10.1029/2019gl082921

Cited by 19 publications

(7 citation statements)

References 51 publications

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“…The robustness of our result is estimated by using different reanalysis data sets and taking into account the decadal modulation of ENSO SPB (Balmaseda et al, ; Lübbecke & McPhaden, ; Fang et al, ). Although the BJ index (black lines, different line styles in Figure a) and the magnitude of each decomposition term (Figures b–f) vary slightly in different versions of data sets (also see Lübbecke & McPhaden, ), two main features are robust: (1) the similar seasonal cycle of BJ index that always has a relatively high value in autumn and a relatively low value in spring and (2) the dominant terms of BJ index that contribute to feature (1) are consistently thermodynamic damping term and thermocline positive term.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…The results (Figures S1 and S2) indicate that the annual mean BJ index decreases with time, linking to a decadal modulation. A weaker annual mean BJ index demonstrates a stronger damping system and an enhanced ENSO SPB (Lübbecke & McPhaden, ; Fang et al, ). However, the pattern of seasonal cycle of BJ index as well as the two dominant terms is still robust, regardless of the different versions of the reanalysis data sets or decadal variations.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…The robustness of our result is estimated by using different reanalysis data sets and taking into account the decadal modulation of ENSO SPB (Balmaseda et al, 1995;Lübbecke & McPhaden, 2014;Fang et al, 2019).…”

Section: Summary and Discussionmentioning

confidence: 99%

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Seasonal Cycle of Background in the Tropical Pacific as a Cause of ENSO Spring Persistence Barrier

Jin

Liu

et al. 2019

Geophysical Research Letters

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Statistical model results suggest that the declining growth rate from autumn to spring is the key to cause El Niño‐Southern Oscillation (ENSO) spring persistence barrier (SPB). Using a dynamical approach, we develop the physical mechanisms responsible for ENSO SPB in the framework of recharge oscillator by adding a seasonally varying Bjerknes (BJ) stability index and linking it with ENSO growth rate. By decomposing BJ index, it is indicated that seasonal thermodynamic damping and thermocline positive feedback play an important role in determining the ENSO SPB. We further show that the increasing/decreasing upper‐level cloud/low‐level cloud and the deepening thermocline from autumn to spring are the main factors to control the SPB of ENSO. Our proposed mechanisms also have useful implications for the understanding of ENSO prediction.

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Section: Summary and Discussionmentioning

confidence: 99%

Section: Summary and Discussionmentioning

confidence: 99%

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Seasonal Cycle of Background in the Tropical Pacific as a Cause of ENSO Spring Persistence Barrier

Jin

Liu

et al. 2019

Geophysical Research Letters

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“…It was documented that the ENSO spring persistence barrier, which is tightly related to the SPB, became stronger after 2000 compared to that in the previous decades (e.g., Fang et al 2019;Liu et al 2019). The main reason for this is the weakening of the memory of the ocean, as reflected in both SST and TCD.…”

Section: (A) (B)mentioning

confidence: 99%

Effect of the air–sea coupled system change on the ENSO evolution from boreal spring

Fang

Zheng

2021

Clim Dyn

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Realistic simulation and accurate prediction of El Niño-Southern Oscillation (ENSO) is still a challenge. One fundamental obstacle is the so-called spring predictability barrier (SPB), which features a low predictive skill of the ENSO with prediction across boreal spring. Our observational analysis shows that the leading empirical orthogonal function mode of the seasonal Niño3.4 index evolution (i.e., from May to the following April) explains nearly 90% of its total variance, and the principle component is almost identical to the Niño3.4 index in the mature phase. This means a good ENSO prediction for a year ranging May-next April can be achieved if the Niño3.4 index in the mature phase is accurately obtained in advance. In this work, by extracting physically oriented variables in the spring, a linear regression approach that can reproduce the mature ENSO phases in observation is firstly proposed. Further investigation indicates that the specific equation, however, is significantly modulated by an interdecadal regime shift in the air–sea coupled system in the tropical Pacific. During 1980–1999, ocean adjustment and vertical processes were dominant, and the recharge oscillator theory was effective to capture the ENSO evolutions. While, during 2000–2018, zonal advection and thermodynamics became important, and successful prediction essentially relies on the wind stress information and their controlled processes, both zonally and meridionally. These results imply that accounting for the interdecadal regime shift of the tropical Pacific coupled system and the dominant processes in spring in modulating the ENSO evolution could reduce the impact of SPB and improve ENSO prediction.

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“…This growth rate, can be regarded as the Bjerknes (BJ) index (Jin et al 2006), which is controlled by the background in the tropical Pacific (Jin et al 2019). This BJ index has been identified to exist decadal modulation (Fang et al 2019). As such, the decadal change of PBs may be caused by the background in the tropical Pacific, which is consistent with Yu and Kao (2007).…”

Section: Understanding the Observational Enso Pbs In Sst And Ohcmentioning

confidence: 99%

A theory of Spring Persistence Barrier on ENSO. Part II: Persistence Barriers in SST and ocean heat content

Jin

Liu

2021

Journal of Climate

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In this paper, we investigate the potential factors that control the relationship between the El Niño-Southern Oscillation (ENSO) persistence barriers (PB) in sea surface temperature (SST) and ocean heat content (OHC) and apply it to explain observational ENSO PBs. With the addition of seasonal growth rate in SST in the neutral recharge oscillator (NRO) model, approximate analytical solutions of autocorrelation functions for SST and OHC suggest strictly that the timing of PB for OHC leads that of SST by half a year and the strength of the two PBs are the same. The numerical solutions of the NRO model also show a similar relationship. The role of ENSO growth rate to PBs in SST and OHC is then identified in the damped and unstable ENSO regime. Therefore, it is suggested that for the observational ENSO, the seasonally varying ENSO growth rate in SST controls PBs in SST and OHC simultaneously.

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Decadal Modulation of ENSO Spring Persistence Barrier by Thermal Damping Processes in the Observation

Cited by 19 publications

References 51 publications

Seasonal Cycle of Background in the Tropical Pacific as a Cause of ENSO Spring Persistence Barrier

Seasonal Cycle of Background in the Tropical Pacific as a Cause of ENSO Spring Persistence Barrier

Effect of the air–sea coupled system change on the ENSO evolution from boreal spring

A theory of Spring Persistence Barrier on ENSO. Part II: Persistence Barriers in SST and ocean heat content

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