Atmospheric dynamics revealed by multi-year measurement of ripple and whole-dune fluxes at active Martian dune fields
Abstract
Aeolian sand dunes are observed across the Martian surface. The arrival of the HiRISE camera at Mars in 2007 enabled detection of modern-day movement of dunes and ripples for the first time. Since 2007, HiRISE has continued to orbit Mars and collected a long timeseries of repeat imagery at some Martian dune fields. We apply these long timeseries of imagery to study the movement and dynamics of dunes and meter-scale ripples at the Nili Patera and Meroe Patera barchan dune fields on Mars.
We present measurements of whole-dune sand fluxes extracted at both dune fields via manual tracking of dune crestlines and slipfaces in HiRISE images. We also present a multi-Mars year timeseries of ripple flux measurements. These were extracted via the use of COSI-Corr, a software package that enables automatic subpixel correlation of features in optical imagery. Ripple fluxes show a consistent pattern of seasonal variation, with maxima in flux during northern-hemisphere autumn and winter at both dune fields. We compare our observed pattern of temporal variation in ripple flux to predictions of the wind regime made by Mars global climate models (GCMs), and test a new technique to correct GCM predictions for the near-surface turbulence and gustiness that are not well resolved in GCMs. Using this analysis, we derive a revised estimate for the effective shear stress required to initiate saltation on Mars.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.P51C..05R
- Keywords:
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- 0343 Planetary atmospheres;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 6225 Mars;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS;
- 5405 Atmospheres;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 5445 Meteorology;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS