An Observational Overview of the Ubiquitous Dust Tides in the Martian Atmosphere

Dust activity on Mars is not physically different in nature from that on Earth, except that it is more intense and critical to the Martian climate under the specific planetary and atmospheric parameters of Mars. Previously found atmospheric dust tides during large Martian dust storms are a significant short-term global-scale dust activity, analogous to Earth's ocean tides. However, it is not certain whether dust tides are widespread on Mars. In this paper, we use multi-local time observations of Martian year (MY) 33 from the Mars Climate Sounder to provide the first detailed overview of dust tides over the entire MY. We generalize two scenarios of dust tides from the spatial distribution of the day-night difference of dust, called the low-latitude scenario and the low-altitude scenario, respectively. The two scenarios are ubiquitous and show distinct seasonal variations. For the first time, we find a downward phase progression signal in the atmospheric dust abundance, similar to the vertical propagation of thermal tides, providing direct evidence for the role of vertically propagated thermal tides in driving the diurnal variations of dust. Utilizing the Lagrangian particle simulation, we show that the diurnal dust motion in both scenarios is driven by meridional and vertical tidal winds. This implies that the associated wind fields can be inferred inversely from the diurnal variations of the airborne dust and can be used to indirectly estimate global wind fields. The relatively simple Martian atmosphere could also be used to test and advance existing theories of Earth's dust activity.