On the Formation Mechanism of the Seasonal Persistence Barrier

The mechanism of the seasonal persistence barrier (SPB) is studied in the framework of an autoregressive (AR) model. In contrast to the seasonal variance, whose minimum is modulated mainly by the minimum growth rate or noise forcing, the SPB is caused primarily by the declining growth rate or increa...

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Bibliographic Details
Published in:Journal of climate 2021-01, Vol.34 (2), p.479-494
Main Authors: Jin, Yishuai, Liu, Zhengyu, He, Chengfei, Zhao, Yuchu
Format: Article
Language:English
Subjects:
Autoregressive models
Autoregressive processes
Calendars
Climate variability
Damping
General circulation models
Growth rate
Noise
Sea surface
Seasons
Signal to noise ratio
Spring
Spring (season)
Surface temperature
Tropical climate
Variability
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Summary:The mechanism of the seasonal persistence barrier (SPB) is studied in the framework of an autoregressive (AR) model. In contrast to the seasonal variance, whose minimum is modulated mainly by the minimum growth rate or noise forcing, the SPB is caused primarily by the declining growth rate or increasing noise forcing, instead of the minimum/maximum of the growth rate or noise forcing. In other words, the SPB is caused by the declining signal-to-noise ratio (SNR) rather than the weakest SNR. In a weakly damped system, the phase of the SPB is delayed from that of declining SNR by about a season. The mechanism is further applied to explain the observed SST variability in the tropical and North Pacific. For the tropical Pacific, the spring SPB could be caused by the decreasing growth rate from September to March and weak annual mean damping rate, instead of the minimum growth rate in spring. Over the North Pacific, the increasing noise forcing from March to June may lead to the summer SPB. Our mechanism provides a null hypothesis for understanding the SPB of climate variability.
ISSN:0894-8755
1520-0442
DOI:10.1175/JCLI-D-19-0502.1