Surface wind flow modelling on Mars

Abstract

Aeolian landforms such as sand dunes are ubiquitous across the surface of Mars, and aeolian transport is the main driving force for sediment transport. Numerical modelling at global and regional scales has provided insights into large scale atmospheric processes forcing geomorphological surface changes. High resolution Computational Fluid Dynamics (CFD) modelling to examine the microscale aeolian process at a sub dune length scale, however, is much rarer. CFD modelling is crucial in assessing dune evolution patterns as it allows for the investigation of microscale atmospheric-surface interactions that lead to geomorphological change.

This thesis aims to extend our knowledge of the microscale forcing processes that contribute to dune evolution on the surface of Mars. In situ meteorological data has been collected from instrumentation onboard multiple Mars rovers and landers. There are limitations to this data however, in particular the low spatial coverage which leaves many sites without in situ data to examine the aeolian processes occurring over dunes. This study developed a combined modelling approach to examine microscale aeolian processes at sites on Mars which lack in situ data. This study used the output of a Global Circulation Model (GCM) and a mesoscale model at several sites to inform CFD modelling simulations throughout the Mars Year.

This study concludes that a combined modelling approach at sites which lack in situ data, provides new insights into dune controls on Mars. The CFD modelling successfully reproduced the findings of previous studies which observed seasonal variation in sediment transport, validated using orbital imagery of the site. This study also provides new insights into the effect of upwind topography on controlling local wind flow patterns which contribute to local dune morphology. This research provides an opportunity to reliably investigate microscale aeolian processes at sites of interest on Mars which require better, spatially intensive wind data.

Date of Award	May 2023
Original language	English
Sponsors	Department for the Economy
Supervisor	Derek Jackson (Supervisor), Andrew Cooper (Supervisor), Timothy Michaels (Supervisor), Jean-Philippe Avouac (Supervisor) & Thomas Smyth (Supervisor)