A theory of Spring Persistence Barrier on ENSO. Part I: The role of ENSO period

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  • 1 Key Laboratory of Physical Oceanography, Ministry of Education/Institute for Advanced Ocean Study/Frontiers Science Center for Deep Ocean Multispheres and Earth System (DOMES), Ocean University of China, Qingdao, China
  • 2 Open studio for Ocean-Climate-Isotope Modeling, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266100, China
  • 3 Atmospheric Science Program, Department of Geography, The Ohio State University, USA
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Abstract

In this paper, we investigate the role of El Niño-Southern Oscillation (ENSO) period in the spring persistence barrier (SPB) mainly using the neutral recharge oscillator (NRO) model both analytically and numerically. It is suggested that a shorter ENSO period strengthens the SPB. Moreover, in contrast to the strict phase locking of the SPB in the Langevin equation, the phase of a SPB is no longer locked exactly to a particular time of the calendar year in the NRO model. Instead, the phases of the SPB for different initial months shift earlier with the maximum persistence decline lag months. In particular, the phase of a SPB will be shifted from the early summer to early spring, corresponding to the initial months of the early half year and later half year. This feature demonstrates that for later half year, ENSO predictability decreases as the presence of ENSO period. For realistic parameters, the range of the phase change is modest, smaller than 2-3 months. Similar phase shift is also identified for the SPB in the damped ENSO regime, unstable ENSO regime and observation. Our theory provides a null hypothesis for the role of ENSO period in SPB.

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Corresponding authors: Yishuai Jin, Key Laboratory of Physical Oceanography, Ministry of Education/Institute for Advanced Ocean Study/Frontiers Science Center for Deep Ocean Multispheres and Earth System (DOMES), Ocean University of China, Qingdao, China, jinyishuai@126.com; Zhengyu Liu, Department of Geography, Ohio State University, liu.7022@osu.edu

Abstract

In this paper, we investigate the role of El Niño-Southern Oscillation (ENSO) period in the spring persistence barrier (SPB) mainly using the neutral recharge oscillator (NRO) model both analytically and numerically. It is suggested that a shorter ENSO period strengthens the SPB. Moreover, in contrast to the strict phase locking of the SPB in the Langevin equation, the phase of a SPB is no longer locked exactly to a particular time of the calendar year in the NRO model. Instead, the phases of the SPB for different initial months shift earlier with the maximum persistence decline lag months. In particular, the phase of a SPB will be shifted from the early summer to early spring, corresponding to the initial months of the early half year and later half year. This feature demonstrates that for later half year, ENSO predictability decreases as the presence of ENSO period. For realistic parameters, the range of the phase change is modest, smaller than 2-3 months. Similar phase shift is also identified for the SPB in the damped ENSO regime, unstable ENSO regime and observation. Our theory provides a null hypothesis for the role of ENSO period in SPB.

Denotes content that is immediately available upon publication as open access.

Corresponding authors: Yishuai Jin, Key Laboratory of Physical Oceanography, Ministry of Education/Institute for Advanced Ocean Study/Frontiers Science Center for Deep Ocean Multispheres and Earth System (DOMES), Ocean University of China, Qingdao, China, jinyishuai@126.com; Zhengyu Liu, Department of Geography, Ohio State University, liu.7022@osu.edu
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