Probabilistic Approaches to The Energy Equality in Forced Surface Quasi-Geostrophic Equations

TL;DR

This paper investigates probabilistic methods to understand the energy equality in forced surface quasi-geostrophic equations, linking stochastic large deviations with deterministic energy properties and exploring the implications for uniqueness and non-Gaussian deviations.

Contribution

It extends large deviation techniques to the forced SQG equation in generalized Sobolev spaces and connects stochastic deviations with deterministic energy equality and uniqueness issues.

Findings

Proves zero-noise large deviations for stochastic SQG.

Shows energy equality holds on time-reversible subsets.

Links non-Gaussian large deviations to deterministic uniqueness.

Abstract

We explore probabilistic approaches to the deterministic energy equality for the forced Surface Quasi-Geostrophic (SQG) equation on a torus. First, we prove the zero-noise dynamical large deviations for a corresponding stochastic SQG equation, where the lower bound matches the upper bound on a certain closure of the weak-strong uniqueness class for the deterministic forced SQG equation. Furthermore, we show that the energy equality for the deterministic SQG equation holds on arbitrary time-reversible subsets of the domain where we match the upper bound and the lower bound. Conversely, the violation of the deterministic energy equality breaks the lower bound of large deviations. These results extend the existing techniques in Gess, Heydecker, and the second author \cite{arXiv:2311.02223} to generalized Sobolev spaces with negative indices. Finally, we provide an analysis of the restricted quasi-potential and prove a conditional equivalence compared to the rate function of large deviations for the Gaussian distribution. This suggests a potential connection between non-Gaussian large deviations in equilibrium for the stochastic SQG equation and the open problem regarding the uniqueness of the deterministic SQG equation.