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| Titel |
First in situ analysis of dust devil tracks on Earth and their comparison with tracks on Mars |
| VerfasserIn |
Dennis Reiss, Jan Raack, Angelo P. Rossi, Gaetano di Achille, Harald Hiesinger |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250051918
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| Zusammenfassung |
| Dust devils are low pressure vortices formed from unstable near surface warm air generated
by insolation and they can be visible due to the entrainment of dust and possibly sand (for
further details, see [1]). On Mars, active dust devils have been observed leaving tracks, which
are mostly darker than their surroundings, although some are brighter [2]. Image data of
the Microscopic Imager (MI) [3] onboard of the Mars Exploration Rover (MER)
Spirit in Gusev crater showed that surfaces consisting of sand grains within dust
devil track zones are relatively free of finer grained dust compared to the bright
regions outside the tracks [4]. It has been suggested that the albedo difference is
caused by the different grain sizes because the brightness is photometrically inversely
proportional to grain size [4]. The thickness of removed material by dust devils on
Mars was estimated to be in the range of 2 – 40 μm [5] based on the results of [6]
at the Mars Pathfinder landing site. Dust devil track simulations with the Mars
Regional Atmospheric Modeling System (MRAMS) indicate removal thicknesses of
1 – 8 μm [7]. [8] estimated removal thicknesses of about 8 μm from active dust
devil observations in Gusev crater. On Earth, dust devil tracks are rare. So far they
were identified in satellite imagery in the Saharan desert [9, 10]. In this study we
report about the first in situ analysis of terrestrial dust devil tracks observed in the
Turpan depression desert in northwestern China [11]. Passages of active dust devils
remove a thin layer of fine grained material (< ~63 μm), cleaning the upper
surface of coarse sands (0.5 – 1 mm). This erosional process changes the photometric
properties of the upper surface causing the albedo differences within the track to the
surroundings. Measurements imply that a removal of an equivalent layer thickness of ~2
μm is sufficient to form the dark dust devil tracks. Our terrestrial results are in
agreement with the mechanism proposed by [4] for the formation of dust devil tracks on
Mars.
References: [1] Balme, M., and R. Greeley (2006), Rev. Geophys., 44, RG3003,
doi:10.1029/2005RG000188. [2] Malin, M.C., and K. S. Edgett (2001), J. Geophys. Res.,
106, 23429-23570. [4] Greeley, R. et al. (2005), J. Geophys. Res., 110, E06002,
doi:10.1029/2005JE002403. [3] Herkenhoff, K. E. et al. (2003), J. Geophys. Res., 108, 8065,
doi:10.1029/2003JE002076. [5] Balme, M.R. et al. (2003), J. Geophys. Res., 108,
5086, doi:10.1029/2003JE002096. [6] Metzger, S. M. et al. (1999), Geophys. Res.
Lett., 26, 2781-2784. [7] Michaels, T. I. (2006), Geophys. Res. Lett., 33, L19S08,
doi:10.1029/2006GL026268. [8] Greeley, R. et al. (2006), J. Geophys. Res., 111, E12S09,
doi: 10.1029/2006JE002743. [9] Rossi, A. P., and L. Marinangeli (2004), Geophys. Res.
Lett., 31, L06702, doi: 10.1029/2004GL019428. [10] Neakrase, L.D.V. et al. (2008) GSA, 40,
abstract 195-19. [11] Reiss, D. et al. (2010) GRL, 37, L14203, doi:10.1029/2010GL044016. |
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