Equatorial Waves Associated with Dust Storms as Simulated in a Mars General Circulation Model

Abstract Equatorial atmospheric waves provide a mechanism for variability on a wide range of timescales and for disturbances in one part of the tropics to influence other tropical locations around the globe. A Mars general circulation model is used to investigate how equatorial waves behave under different atmospheric dust loading scenarios and when perturbed by dust storms. Such waves may be important for understanding triggering of distant dust storms or additional dust lifting centers within large storms. Equatorial waves appear to change when dust storm sequences cross the equator or when background dust amounts significantly vary, with eastward- and westward-propagating waves within a wide spectral interval being amplified in general. Specifically, many low-frequency, long-wavelength equatorial waves become prominent during prescribed dust storm episodes. Their horizontal wave structures seen in the 100 Pa geopotential field show a resemblance to equatorial Rossby, Kelvin, and mixed Rossby–gravity waves. Waves with different wave periods and zonal wavenumbers evolve with time and interfere with each other, leading to complex time-dependent eddy patterns. This study shows that both dust storms and background dust can significantly influence the spectra and structures of eddies in the tropical Martian atmosphere.