Deliquescence probability maps of Mars and key limiting factors using GCM model calculations

There may be a chance of small-scale ephemeral liquid water formation on present-day Mars, even though the current climate does not support the existence of larger bodies of water. Through a process called deliquescence, hygroscopic salts can enter solution by absorbing water vapor directly from the atmosphere. Due to the absence of in-situ deliquescence experiments so far, the most reliable way to forecast deliquescence is through atmospheric modeling; however, the locations and times when salty liquid water could emerge are not yet well known. In this paper, we present our results of likely brine formation on Mars, its proposed locations and seasons, as well as the possible limiting factors. For our calculations we used the data of Laboratoire de Météorologie Dynamique Mars General Circulation Model version 5. The results show that from Ls35∘ - Ls160∘, between 9 PM and 11 PM there is a good chance for calcium perchlorate deliquescence above 30∘ N, while in this zone the ideal regions are concentrated mostly to Acidalia Planitia and Utopia Planitia. We found that in the Southern Hemisphere, between Ls195∘ and Ls320∘, there is a noticeable, but weaker, band in the vicinity of 60∘ S, and both Argyre Planitia and Hellas Planitia show some chance for brine formation. According to our results, the key limiting circumstance of deliquescence could be relative humidity in most cases, when the circumstances are nearly ideal (with the exception of one factor only). Our results suggest that during summer–early fall seasons, there could be deliquescence in both hemispheres in specific areas from the late evening until the early morning hours. There are only few studies detailing the geological and temporal distribution of brine formation through deliquescence; thus, this work could be used as a good guide for future landing site analysis or in choosing a specific location for further research.