Diffusive behavior of transport noise on $\mathbb{S}^2$

TL;DR

This paper studies how transport noise influences diffusion in spherical flows, showing that properly scaled noise induces energy dissipation while maintaining enstrophy, with implications for geophysical fluid modeling.

Contribution

It provides a theoretical and numerical analysis of transport noise effects on diffusion on the sphere, extending previous work from the torus to spherical geometry.

Findings

Transport noise induces energy dissipation on the sphere.

Enstrophy is preserved under appropriately scaled noise.

Numerical simulations confirm theoretical predictions.

Abstract

We investigate theoretically and numerically transport noise-induced diffusion in flows on the sphere. Previous analysis on the torus demonstrated that suitably chosen transport noise in the Euler equations leads to diffusive behavior resembling the Navier--Stokes equations. Here, we analyze dynamics on the sphere with noise-induced differential elliptic operator dissipation and characterize their energy and enstrophy decay properties. Through structure-preserving numerical simulations with the Zeitlin discretization, we demonstrate that appropriately scaled transport noise induces energy dissipation while preserving enstrophy and coadjoint orbits. The presented analysis lays a groundwork for further theoretical investigation of transport noise and supports the calibration of transport noise models as a parametrization for unresolved processes in geophysical fluid simulations.