A priori estimates for the 3D quasi-geostrophic system

TL;DR

This paper develops a priori estimates for the 3D dissipative quasi-geostrophic system, which models atmospheric and oceanic flows under strong rotation and stratification, using advanced mathematical analysis of non-local operators.

Contribution

It introduces refined methods to analyze the non-local operator in the 3D QG system and establishes a priori estimates in the L^p setting, advancing understanding of solution lifespan.

Findings

Established a priori estimates for the 3D QG system

Analyzed the non-local operator's properties and commutator with Lagrangian changes

Provided bounds that relate to solution lifespan in primitive equations

Abstract

The present article is devoted to the 3D dissipative quasi-geostrophic system (QG). This system can be obtained as limit model of the Primitive Equations in the asymptotics of strong rotation and stratification, and involves a non-radial, non-local, homogeneous pseudo-differential operator of order 2 denoted by $\Gamma$ (and whose semigroup kernel reaches negative values). After a refined study of the non-local part of $\Gamma$, we prove apriori estimates (in the general L^p setting) for the 3D QG-model. The main difficulty of this article is to study the commutator of $\Gamma$ with a Lagrangian change of variable. An important application of these a priori estimates, providing bound from below to the lifespan of the solutions of the Primitive Equations for ill-prepared blowing-up initial data, can be found in a companion paper.