This page describes the dust devil research carried out in the past decade by a group of planetary scientists and geologists, working on both Earth and Mars based topics. Over the last few years we have carried out several field campaigns chasing and studying dust devils, attempting to understand their origins and processes. To date, we have "caught" over 70 dust devil vortices, some being measured repeatedly.
The work and instruments are described in the fieldwork section, while the images directory has some nice pictures. The 'Dust Devils on Mars' section has an overview of martian dust devils, plus a description of the detection of dust devils in Mars Pathfinder pictures by Metzger, Carr and others.
Part of this work was aimed at testing the Environmental Sensors Suite on Beagle 2 on the Earth, before they were used on Mars. Overall, to date this ongoing work has involved nearly two dozen investigators from three countries and is now entering its second decade.
Click on many of the pictures for a larger image...
Dust devils form on those numerous calm or gentle breeze summer days when the background wind is not strong enough to lift dust. Also, they can often erode soil and dust from resistant surfaces that regular wind storms can't erode. Since their columns reach much higher than most regular dusty winds, it means that they might influence the downwind air quality and climate a continent or ocean away. Combining all these factors they appear to be quite effective at affecting air quality, although there has only been a small amount of work investigating this.
Our research seeks to:
1. Describe the behaviour of dust devils in a detailed and conceptually comprehensive manner, and relate that meteorological signature to ambient weather conditions,
2. Determine the processes that make these vortices into such effective soil erosion systems, and
3. Apply these understandings to the development of environmental sensors and procedures for use in exploring the global dust cycle on Mars.
To achieve these goals we rely on logging field observations, installation of weather stations, geologic and aerodynamic surface mapping, chasing and direct sampling of dust devils, laboratory simulations, and theoretical modeling.
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Dust devils are rotating columns of dust and air that are common over many arid regions of Earth and Mars. Although dust devils appear similar to tornados, they are powered by a very different "thermal convection vortex engine". Cloud-free skys and gentle breezes allow sunshine [1] to warm the desert surface. The hot dust layer [2] then warms the air immediately above it This ground air layer becomes much hotter than the air only a few feet further above the surface; creating an unstable local condition. Bubbles of hot air [3] then collect and break free from the ground layer. A nudge from a breeze is all it takes to initiate a twisting vortex column, which in turn gathers more of the ground-level hot air that sustains the process. A fast-spinning vortex becomes a dust devil once the wind speeds are strong enough to lift the local dust. |
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Refereed papers
Greeley, R., M.R. Balme, J. Iversen, S. Metzger, B. Mickelson, J. Phoreman, and B. White, Martian dust devils: Laboratory simulations of particle threshold, J. Geophys. Res., in press (2004).
Balme, M; Metzger, S; Towner, M; Ringrose, T; Greeley, R; Iversen, J, Friction wind speeds in dust devils: A field study, Geophys. Res. Lett, Volume 30, Issue 16, pp. ASC 1-1, CiteID 1830, DOI 10.1029/2003GL017493 (abstract) (2003).
Houser, J. G., W. M. Farrell, and S. M. Metzger, ULF and ELF magnetic activity from a terrestrial dust devil, Geophys. Res. Lett., v.30, no.1, p. 1027, doi:10.1029/2001GL014144 (2003).
Ringrose, T. J.; Towner, M. C.; Zarnecki, J. C., Convective vortices on Mars: a reanalysis of Viking Lander 2 meteorological data, sols 1-60, Icarus, Volume 163, Issue 1, p. 78-87 (abstract) (2003).
Metzger, S.M., Johnson, J.R., Carr, J.R., Parker, T.J., and Lemmon, M., Techniques for identifying dust devils in Mars Pathfinder images, IEEE Transactions on Geoscience and Remote Sensing, v. 38, no. 2, p. 870-876 (2000).
Metzger, S. M.; Carr, J. R.; Johnson, J. R.; Parker, T. J.; Lemmon, M. T. (1999), Dust devil vortices seen by the Mars Pathfinder camera, Geophys. Res. Lett, Volume 26, Issue 18, p.2781-2784 (abstract) (1999).
Conference proceedings
Metzger, S. M., Promoting a Well-established Study Site for Mars Analog and Desert Process Studies, Lunar and Planetary Science Conference #2048 (2003)
Towner, M. C.; Ringrose, T. J.; Balme, M.; Greeley, R.; Zarnecki, J. C., Measurements of Dust Devil Lower Structure and Properties, El Dorado Valley, Nevada, June 2002, AGU abstract #P51A-0342 (2002)
Metzger, S. M.; Balme, M.; Greeley, R.; Ringrose, T.; Towner, M., Field Studies of Very-Near Surface Dust Devil Processes, AGU abstract #P51A-0341 (2002)
Ringrose, T. J.; Zarnecki, J. C., Martian and Terrestrial Dust Devils, Lunar and Planetary Science Conference #1183 (2002)
Metzger, S. M., Recent Advances in Understanding Dust Devil Processes and Sediment Flux on Earth and Mars, Lunar and Planetary Science Conference #2157 (2001)