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Diurnal Variation in Martian Dust Devil Activity

Chapman, R. M.; Lewis, S. R.; Balme, M. and Steele, L. J. (2017). Diurnal Variation in Martian Dust Devil Activity. Icarus, 292 pp. 154–167.

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DOI (Digital Object Identifier) Link: https://doi.org/10.1016/j.icarus.2017.01.003
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Abstract

We show that the dust devil parameterisation in use in most Mars Global Circulation Models (MGCMs) results in an unexpectedly high level of dust devil activity during morning hours.

Prior expectations of the diurnal variation of Martian dust devils are based mainly upon the observed behaviour of terrestrial dust devils: i.e. that the majority occur during the afternoon. We instead find that large areas of the Martian surface experience dust devil activity during the morning in our MGCM, and that many locations experience a peak in dust devil activity before mid-sol.

We find that the diurnal variation in dust devil activity is governed by near-surface wind speeds. Within the range of daylight hours, higher wind speeds tend to produce higher levels of dust devil activity, rather than the activity simply being governed by the availability of heat at the planet's surface, which peaks in early afternoon.

Evidence for whether the phenomenon we observe is real or an artefact of the parameterisation is inconclusive. We compare our results with surface-based observations of Martian dust devil timings and obtain a good match with the majority of surveys. We do not find a good match with orbital observations, which identify a diurnal distribution more closely matching that of terrestrial dust devils, but orbital observations have limited temporal coverage, biased towards the early afternoon.

We propose that the generally accepted description of dust devil behaviour on Mars is incomplete, and that theories of dust devil formation may need to be modified specifically for the Martian environment. Further surveys of dust devil observations are required to support any such modifications. These surveys should include both surface and orbital observations, and the range of observations must encompass the full diurnal period and consider the wider meteorological context surrounding the observations.

Item Type: Journal Item
Copyright Holders: 2017 The Authors
ISSN: 0019-1035
Project Funding Details:
Funded Project NameProject IDFunding Body
(Aurora Studentship) Martian Regional Dust Storms: Implications for Entry, Descent and LandingST/M00306X/1UK Space Agency (UKSA)
Astronomy and Planetary Sciences at the Open UniversityST/L000776/1STFC (Science & Technology Facilities Council)
Keywords: Mars, atmosphere; Mars, climate; Mars, surface
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 48113
Depositing User: Rhian Chapman
Date Deposited: 10 Jan 2017 17:05
Last Modified: 14 Jun 2017 10:38
URI: http://oro.open.ac.uk/id/eprint/48113
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