Seasonal Water "Pump" in the Atmosphere of Mars: Vertical Transport to the Thermosphere
Abstract
Water is the main source of hydrogen in the atmosphere of Mars. It concentrates in the troposphere, while hydrogen outgassing takes in the thermosphere. Because the middle atmosphere is too cold to sustain water vapor, it was not clear how water is transported from the lower to the upper atmosphere. We applied a state-of-the-art global circulation model to elucidate the transport mechanism. For the first time, simulations revealed the full picture of water cycle from the ground to the thermosphere. Water is lifted up by the upwelling over the southern hemisphere only at perihelion seasons. There, it is transported across latitudes, partially is photodissociated, and partially returned back to the lower atmosphere over the winter pole. Dust storms strongly modulate the global transport cell and the transport of water, in particular. Solar tide acts as a "pump" by increasing the transport during certain local times and almost completely shutting it down during others. The obtained results are important for quantifying the present day Mars climate, explaining the past and predicting future changes.
- Publication:
-
EPSC-DPS Joint Meeting 2019
- Pub Date:
- September 2019
- Bibcode:
- 2019EPSC...13...53S