The Semigeostrophic-Euler Limit: Lifespan Lower Bounds and $O(\varepsilon)$ Velocity Stability

Fuente: arXiv
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Main Author: Armegioiu, Victor
Format: Preprint
Published: 2026
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author Armegioiu, Victor
author_facet Armegioiu, Victor
contents We study the two-dimensional semigeostrophic system on the flat torus in the small-amplitude scaling and quantify its approximation by incompressible Euler in dual variables. On a natural perturbative bootstrap window for the Monge--Ampère coupling, we prove two strong stability results: an $O(\eps)$ estimate for the velocity in $L^2$, and an $O(\eps)$ estimate in Wasserstein distance for the associated physical densities. The latter is deduced from a more general comparison theorem, independent of the bootstrap regime, which combines the deterministic flow representation for the smooth Euler solution with a superposition representation for the semigeostrophic continuity equation. We also prove a lifespan lower bound with a logarithmic improvement over the standard hyperbolic scale, namely $T_*(\eps)\gtrsim \eps^{-1}\log\log(1/\eps)$ in physical time.
format Preprint
id arxiv_https___arxiv_org_abs_2601_04797
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The Semigeostrophic-Euler Limit: Lifespan Lower Bounds and $O(\varepsilon)$ Velocity Stability
Armegioiu, Victor
Analysis of PDEs
Fluid Dynamics
We study the two-dimensional semigeostrophic system on the flat torus in the small-amplitude scaling and quantify its approximation by incompressible Euler in dual variables. On a natural perturbative bootstrap window for the Monge--Ampère coupling, we prove two strong stability results: an $O(\eps)$ estimate for the velocity in $L^2$, and an $O(\eps)$ estimate in Wasserstein distance for the associated physical densities. The latter is deduced from a more general comparison theorem, independent of the bootstrap regime, which combines the deterministic flow representation for the smooth Euler solution with a superposition representation for the semigeostrophic continuity equation. We also prove a lifespan lower bound with a logarithmic improvement over the standard hyperbolic scale, namely $T_*(\eps)\gtrsim \eps^{-1}\log\log(1/\eps)$ in physical time.
title The Semigeostrophic-Euler Limit: Lifespan Lower Bounds and $O(\varepsilon)$ Velocity Stability
topic Analysis of PDEs
Fluid Dynamics
url https://arxiv.org/abs/2601.04797