AIRFLOW MODELLING AND RIPPLE MIGRATION PATTERNS ACROSS DUNE TOPOGRAPHY IN PROCTOR CRATER, MARS

Sand dunes inside Martian craters are prominent landforms on much of the recent Hi-Rise imagery available. Complex but regular aeolian-driven patterns are clearly evident and form distinctive dune-fields. Associated smaller-scale bedforms (ripples) draped on top of the larger dunes are clearly visible on the HiRISE imagery (0.3m resolution), enabling analysis of localised landform migration patterns from near-surface wind forcing. Understanding airflow conditions over and around these landforms helps unravel the formational patterns and orientation of the aeolian bedforms.

The stereoscopic HiRISE data enables detailed 3D surfaces to be generated which can then be used as surface topography over which 3D airflow models can be run. Sequential imagery at this scale also allows ripple migration analysis in conjunction with airflow modelling. Here, we use computational fluid dynamics modelling and present some preliminary findings within Mars’ Proctor Crater over a dune area measuring 4.5km x 5.0km running with a computational cell resolution of 5m x 5m. A range of wind speed and directions are investigated and results are compared to bedform orientation, length scale and migration of ripples. Our results show a distinctive relationship between steered airflow and localised bedform (ripple) orientation and migration directions. The importance of using appropriately (micro)scaled wind modelling when studying dune dynamics on Mars rather than applying only meso-scale wind models is demonstrated.

These findings have important implications in our understanding of evolutionary and contemporary dynamics of aeolian dunes on Mars and further support recent studies examining migration activity in Martian sand dunes.