Numerical Modeling of Orbit-Spin Coupling Accelerations in a Mars General Circulation Model: Implications for Global Dust Storm Activity

TL;DR

This study uses a modified Mars general circulation model to test a hypothesis that orbit-spin coupling influences Martian atmospheric dynamics, successfully reproducing conditions associated with global dust storms during perihelion seasons.

Contribution

The paper introduces a GCM that incorporates orbit-spin coupling accelerations, providing the first numerical evidence supporting their role in Martian dust storm activity.

Findings

Reproduces conditions favorable for global dust storms during perihelion.

Shows increased meridional circulation and surface winds during dust storm seasons.

Supports the orbit-spin coupling hypothesis as a mechanism influencing Martian climate.

Abstract

We employ the MarsWRF general circulation model (GCM) to test the predictions of a new physical hypothesis: a weak coupling of the orbital and rotational angular momenta of extended bodies is predicted to give rise to cycles of intensification and relaxation of circulatory flows within atmospheres. The dynamical core of the GCM has been modified to include the orbit-spin coupling accelerations due to solar system dynamics for the years 1920-2030. The modified GCM is first subjected to extensive testing and validation. We compare forced and unforced model outcomes for large-scale zonal and meridional flows, and for near-surface wind velocities and surface wind stresses. The predicted cycles of circulatory intensification and relaxation within the modified GCM are observed. Most remarkably, the modified GCM reproduces conditions favorable for the occurrence of perihelion-season global-scale dust storms on Mars in years in which such storms were observed. A strengthening of the meridional overturning (Hadley) circulation during the dust storm season occurs in the GCM in all previously known years with perihelion-season global-scale dust storms. The increased upwelling produced in the southern hemisphere in southern summer may facilitate the transport of dust to high altitudes in the Mars atmosphere during the dust storm season, where radiative heating may further strengthen the circulation. Significantly increased surface winds and surface wind stresses are also obtained. These may locally facilitate saltation and dust lifting from the surface. The numerical simulations constitute proof of concept for the orbit-spin coupling hypothesis under evaluation.