Geometric early warning indicator from stochastic separatrix structure in a random two-state ecosystem model

Fuente: arXiv
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Autores principales: Shi, Yuzhu, Serdukova, Larissa, Zheng, Yayun, Petrovskii, Sergei, Lucarini, Valerio
Formato: Preprint
Publicado: 2026
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author Shi, Yuzhu
Serdukova, Larissa
Zheng, Yayun
Petrovskii, Sergei
Lucarini, Valerio
author_facet Shi, Yuzhu
Serdukova, Larissa
Zheng, Yayun
Petrovskii, Sergei
Lucarini, Valerio
contents Under-ice blooms in the Arctic can develop rapidly under conditions where conventional early warning signals based on critical slowing down fail due to strong noise or limited observational records. We analyze noise-induced transitions in a temperature phytoplankton stochastic differential equation model exhibiting bistability between background and bloom states. The committor function defines a stochastic separatrix as its 1/2-isocommittor, and the normal width of the associated transition layer yields a geometric indicator via arc-length averaging. Under systematic variation of noise intensity, this indicator scales linearly with noise strength, while the logarithm of the mean first passage time follows the Freidlin-Wentzell asymptotic law. Eliminating the noise parameter produces an affine scaling between the logarithmic transition time and the inverse square of the geometric indicator. The relation is robust under variations in discretization, neighborhood definition, and diffusion structure, and holds in the weak noise regime where the transition-layer width scales linearly with noise strength. Unlike variance or lag-one autocorrelation, the geometric indicator remains well defined when rapid transitions preclude reliable time-series estimation. These results provide a geometrically interpretable precursor of bloom onset that may support model-based ecological monitoring in high-variability Arctic systems.
format Preprint
id arxiv_https___arxiv_org_abs_2603_08861
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Geometric early warning indicator from stochastic separatrix structure in a random two-state ecosystem model
Shi, Yuzhu
Serdukova, Larissa
Zheng, Yayun
Petrovskii, Sergei
Lucarini, Valerio
Dynamical Systems
Probability
Chaotic Dynamics
Populations and Evolution
37H20, 37N25, 60H10
Under-ice blooms in the Arctic can develop rapidly under conditions where conventional early warning signals based on critical slowing down fail due to strong noise or limited observational records. We analyze noise-induced transitions in a temperature phytoplankton stochastic differential equation model exhibiting bistability between background and bloom states. The committor function defines a stochastic separatrix as its 1/2-isocommittor, and the normal width of the associated transition layer yields a geometric indicator via arc-length averaging. Under systematic variation of noise intensity, this indicator scales linearly with noise strength, while the logarithm of the mean first passage time follows the Freidlin-Wentzell asymptotic law. Eliminating the noise parameter produces an affine scaling between the logarithmic transition time and the inverse square of the geometric indicator. The relation is robust under variations in discretization, neighborhood definition, and diffusion structure, and holds in the weak noise regime where the transition-layer width scales linearly with noise strength. Unlike variance or lag-one autocorrelation, the geometric indicator remains well defined when rapid transitions preclude reliable time-series estimation. These results provide a geometrically interpretable precursor of bloom onset that may support model-based ecological monitoring in high-variability Arctic systems.
title Geometric early warning indicator from stochastic separatrix structure in a random two-state ecosystem model
topic Dynamical Systems
Probability
Chaotic Dynamics
Populations and Evolution
37H20, 37N25, 60H10
url https://arxiv.org/abs/2603.08861