A Stochastic Parameterization of Non-Orographic Gravity Waves Induced Mixing for Mars Planetary Climate Model

TL;DR

This paper develops a stochastic parameterization scheme for non-orographic gravity wave-induced mixing in Mars climate models, improving understanding of upper atmospheric dynamics and tracer transport.

Contribution

It introduces a unified formalism integrating GW-induced turbulence with stochastic schemes, providing a new way to simulate upper atmospheric mixing on Mars.

Findings

Eddy diffusion coefficient ranges from 1E4 to 1E9 cm2 s-1

Turbopause occurs at 70 to 140 km altitude, varying seasonally

Mixing impacts upper atmospheric tracer abundances and escape processes

Abstract

This paper presents a formalism of mixing induced by non-orographic gravity waves (GWs) to integrate with the stochastic GWs scheme in the Mars Planetary Climate Model. We derive the formalism of GWs and their mixing under the same assumptions, integrating the two schemes within a unified framework. Specifically, a surface-to-exosphere parameterization of GW-induced turbulence has been derived in terms of the eddy diffusion coefficient. Simulations show that the coefficient is on the order of 1E4 to 1E9 cm2 s-1 and a turbopause is at altitudes of 70 to 140 km, varying with seasons. The triggered mixing has minor effects on model temperatures, yet it substantially impacts upper atmospheric abundances. Simulations are consistent with observations from the Mars Climate Sounder and the Neutral Gas and Ion Mass Spectrometer. Mixing enhances the tracer transports in the middle and upper atmosphere, governing the dynamics of these regions. The scheme reveals how non-orographic GW-induced turbulence can regulate upper atmospheric processes, such as tracer escape.