Seasonal, annual, and multidirectional sand flux trends related to global or regional forcing factors

NASA Mars Data Analysis Program

Start Date: 09/01/2021
Project #: 1815
End Date: 08/31/2025
Award #: 80NSSC21K1096

PSI Personnel

Non PSI Personnel: Dr. Simone Silvestro (Co-Investigator, Carl Sagan Center, SETI Institute, Mountain View, CA), Dr. David Vaz (Co-Investigator, Centre for Earth and Space Research of the University of Coimbra, Coimbra, Portugal)

Project Description

Background and Motivation – Wind has been an enduring geologic agent throughout Mars’ history, but it is often unclear when, where, and why sediment is mobile in the current epoch. Spatial variations in sand fluxes relate to external forcing factors (i.e., boundary conditions), some of which may be unique to the red planet (e.g., seasonal frost, lack of vegetation). Much of our knowledge about aeolian bedform (dunes and ripples) migration on Mars is thanks to repeat imaging by the High Resolution Imaging Science Experiment (HiRISE) camera onboard MRO.

Prior HiRISE surveys of dunes have shown variable bedform activity across Mars, but the majority of studies have focused on repeat observations with sufficient duration to detect geomorphic changes (2-4 Mars years). While these approaches demonstrate general trends in regional aeolian changes, these results disregard any year-to-year or seasonal variability in the winds. For example, there have been two planet-encircling dust events (2007 and 2018) in the ~7 Mars years that MRO/HiRISE has been operating in martian orbit (2006-2020; Mars year 28-35). Additionally, local dust events and annual surface temperature variability have likely had some impact on the geomorphic effectiveness of regional winds.

More recently, it was found some dune field dynamics are subject to multi-directional wind regimes (orthonogonal or converging) (Chojnacki et al. 2019, Geology). The nature and occurrence of seasonally variable winds and dust storms are lost in long-baseline (multiple Mars year) measurements of bedform activity but could be better understood from more focused investigations.

Science Goals and Objectives – Here, we explore the hypothesis that wind regimes on Mars, as inferred by the sand fluxes of ripples and dunes, vary in magnitude and direction in response to global and regional forcing factors. The science questions in this proposed effort include: What are the annual variations in bedform sand fluxes and how do those compare with long-baseline measurements? Do winds associated with planet encircling or regional dust storms impact sediment transport at a scale that can be quantified by HiRISE? For dune fields influenced by multiple wind regimes, what are the variations in sand fluxes and how do those compare with results from meso-scale modeling?

Proposed Methodology – This project consists of three main tasks to better assess how Martian sand transport varies spatially and temporally – particularly, the dynamics of sand dunes and ripples, collectively termed here as aeolian bedform systems:

Task 0: Generate additional seasonal and annual HiRISE orthoimages of select dune and ripple monitoring sites to be used for Tasks 1-3.

Task 1: Examine the sand flux and directional variability of multi-directional aeolian systems influenced by multiple wind regimes. Constrain these findings to that of local topography, meso-scale models, and regional boundary conditions.

Task 2: For 15-20 sites with appropriate monitoring data quantify annual volumetric sediment fluxes between Mars years 28-35 in comparison to planetary forcing factors (e.g., regional dust storms, global temperature trends etc.).

Task 3: For a dozen sites, explore the surface response of aeolian bedform systems to the Mars year 28 and 34 planet-encircling dust storms. Compare results to those of Task 2 annual series of fluxes.

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