Stormy water on Mars: The distribution and saturation of atmospheric water during the dusty season

Abstract

The loss of water from Mars to space is thought to result from the transport of water to the upper atmosphere, where it is dissociated to hydrogen and escapes the planet. Recent observations have suggested large, rapid seasonal intrusions of water into the upper atmosphere, boosting the hydrogen abundance. We use the Atmospheric Chemistry Suite on the ExoMars Trace Gas Orbiter to characterize the water distribution by altitude. Water profiles during the 2018–2019 southern spring and summer stormy seasons show that high-altitude water is preferentially supplied close to perihelion, and supersaturation occurs even when clouds are present. This implies that the potential for water to escape from Mars is higher than previously thought.

Properties of Water Ice and Dust Particles in the Atmosphere of Mars During the 2018 Global Dust Storm as Inferred From the Atmospheric Chemistry Suite

“…MCS/MRO was observing the Martian atmosphere using limb scanning over the duration of the GDS in the thermal IR range (463 cm −1 or 21.6 µm; Kleinböhl et al, 2020). We can qualitatively compare our retrieved dust mass loadings ( Figure 8, panels e and j) with MCS dust extinctions (top and middle panels of Figure 2 from Kleinböhl et al, 2020 and accompanying text), noting that the aerosol extinction can be considered as a proxy to aerosol mass loading, as shown by Fedorova et al (2020). The MCS observations before and during the peak of the GDS performed at local times of 3 a.m. and 3 p.m. were related to ACS observations at the morning and at the evening terminators, respectively.…”

“…Our results on water ice clouds can be analyzed together with simultaneous water vapor measurements by ACS NIR. Figure 10 (panels a–c) shows temperature and water vapor profiles from NIR spectra (Fedorova et al., 2020) and water ice mass loading retrieved as described above. Before the GDS, water ice particles at high and middle latitudes were found where the water contents and the temperature were low (< 1 ppm vmr of water and T ≤ 150 K), suggesting that nearly all water vapor has condensed.…”

Martian Water Ice Clouds During the 2018 Global Dust Storm as Observed by the ACS‐MIR Channel Onboard the Trace Gas Orbiter

“…A rapid increase of the H O and HDO abundances at altitudes between 40 and 80 km (Vandaele et al, ) was observed during MY 34 storm and recently reproduced in a GCM simulation (Neary et al, ). This large augmentation of the high‐altitude water content is believed to boost hydrogen, or nearly equivalently, water escape from Mars (Chaffin et al, ; Fedorova et al, ; Heavens et al, ). However, the formation of clouds impacts the ability of water (or hydrogen) to escape as it confines (in theory) a significant fraction of water below the cloud level.…”

Mars: Life, Subglacial Oceans, Abiogenic Photosynthesis, Seasonal Increases and Replenishment of Atmospheric Oxygen

“…Levels of oxygen in the soil, oceans, and atmosphere of Earth, also vary according to the season and increase during the Spring and Summer due to fluctuations in the biological activity of photosynthesizing organisms (Keeling and Shertz 1992;Kim et al 2019) and as related to increases in temperature and the availability of water and water vapor condensation and precipitation (Buenning et al 2012;Keeling and Shertz 1992). These seasonal fluctuations on Earth parallel the Spring/Summer increases in oxygen, temperature and water availability on Mars (Fedorova et al 2020;Read and Lewis 2004;Smith 2004;Todd et al 2017;Trainer et al 2019); and these variations on Mars parallel seasonable increases in biological activity and the respiration of oxygen on Earth.…”

“…Based on data provided by orbital observations and the Mars Science Laboratory and its Environmental Monitoring Station, four major reservoirs of Martian water have been identified, i.e. in the northern and south poles (Kieffer et al 1992;Farmer et al 1977;Orosei et al 2018Orosei et al , 2020Lauro et al 2020), in the upper atmosphere which is subject to "large, rapid seasonal intrusions of water" with large portions of the atmosphere becoming supersaturated during the Spring and Summer (Fedorova et al 2020), and within atmospheric vapors every spring and summer (Farmer et al 1977;Korablev et al 2001;Smith et al 2001;Read and Lewis 2004;Smith 2004;Todd et al 2017). These columns of water vapor may also contribute to the formation of Martian clouds observed by several investigators (Kahn 1984;Whiteway et al 2009;Moores et al 2015); and which, like the clouds of Earth, probably contain high concentrations of water.…”