MARTIAN PALEOLAKE MORPHOLOGIES AS A RECORD OF ANCIENT PRECIPITATION AND ARIDITY REGIMES (Invited Presentation)

Despite the abundance of in-situ and remote sensing data revealing hydrological activity in the past, the ancient climate of Mars remains an enigma. Results from geomorphic studies, geochemical observations, and climate models continually fuel debates on the amount, distribution, and nature of surface water and precipitation (e.g., rain vs. snow). In this study we combined measurements of 96 open- and closed-basin lakes with simple hydrological balances to constrain catchment-averaged precipitation, P_T, integrated over a given runoff episode of indeterminate length during early Mars history. We included 13 systems containing both open- and closed-basin lakes, providing fully bounded precipitation estimates (coupled systems). We show that, on average, P_T was ≳4 m and ≲159 m; however, local precipitation was spatially variable and consistent with a complex, planet-wide climate. Aridity indexes, AI, of open-basin lakes indicate some regions may have been at least as humid as semi-arid terrestrial environments (AI > 0.26). Our results offer widely distributed, quantitative hydro-climate constraints to test paleoclimate model scenarios, working towards bridging the gap between geological observations and climate theory for early Mars.