Determination of the wind induced detachment threshold for granular material on Mars using wind tunnel simulations

Merrison, J.P.; Gunnlaugsson, H. P.; Nørnberg, P.; Jensen, Anders Skriver; Rasmussen, K. R.

doi:10.1016/j.icarus.2007.04.035

Cited by 82 publications

(112 citation statements)

References 42 publications

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“…We argue that both of these are plausible mechanisms by which the 'effective dust cover' of a gridpoint may increase over time without the input of any extra dust through deposition. Interestingly, with regard to the second mechanism, Merrison et al (2007) claimed that the formation of aggregates would require the presence of a certain minimum dust depth, which provides some empirical support for the existence of an inverse relationship between surface dust density and lifting threshold, as has been assumed in this work.…”

Section: The Resupply Termsupporting

confidence: 69%

Simulating the interannual variability of major dust storms on Mars using variable lifting thresholds

Mulholland

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Lewis

2013

Icarus

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The redistribution of a finite amount of Martian surface dust during global dust storms and in the intervening periods has been modelled in a dust lifting version of the UK Mars General Circulation Model. When using a constant, uniform threshold in the model's wind stress lifting parameterisation and assuming an unlimited supply of surface dust, multiannual simulations displayed some variability in dust lifting activity from year to year, arising from internal variability manifested through surface wind stress, but dust storms were limited in size and formed within a relatively short seasonal window. Lifting thresholds were then allowed to vary at each model gridpoint, dependent on the rates of emission or deposition of dust. This enhanced interannual variability in dust storm magnitude and timing, such that model storms could cover most of the observed ranges in size and initiation date within a single multiannual simulation. Peak storm magnitude in a given year was primarily determined by the availability of surface dust at a number of key sites in the southern hemisphere. The observed global dust storm (GDS) frequency of roughly one in every three years was approximately reproduced, but the model failed to generate these GDSs spontaneously in the southern hemisphere, where they have typically been observed to initiate. After several years of simulation, the surface dust density field showed good qualitative agreement with the observed pattern of Martian surface dust cover. The model produced a net northward cross-equatorial dust mass flux, which necessitated the addition of an artificial threshold decrease rate in order to allow the continued generation of dust storms over the course of a multiannual simulation. At standard model resolution, for the southward mass flux due to cross-equatorial flushing storms to offset the northward flux due to GDSs on a timescale of ∼ 3 3 years would require an increase in the former by a factor of 3-4. Results at higher model resolution and uncertainties in dust vertical profiles mean that this nevertheless appears to be a plausible explanation for the observed GDS frequency.

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Section: The Resupply Termsupporting

confidence: 69%

Simulating the interannual variability of major dust storms on Mars using variable lifting thresholds

Mulholland

Read

Lewis

2013

Icarus

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“…It is of importance when utilizing the recirculating system that the area of the return flow is comparable (if not greater than) to that of the wind tunnel in order to minimize turbulence and irregularities in the wind stream. Fins are used to minimize rotation effects on the wind by the fan (Merrison et al 2002(Merrison et al , 2004(Merrison et al , 2007(Merrison et al , 2010(Merrison et al , 2012.…”

Section: The Aarhus Wind Tunnel Simulator (Awts) University Of Aarhumentioning

confidence: 99%

Earth as a Tool for Astrobiology—A European Perspective

et al. 2017

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Scientists use the Earth as a tool for astrobiology by analyzing planetary field analogues (i.e. terrestrial samples and field sites that resemble planetary bodies in our Solar System). In addition, they expose the selected planetary field analogues in simulation chambers to conditions that mimic the ones of planets, moons and Low Earth Orbit (LEO) space conditions, as well as the chemistry occurring in interstellar and cometary ices. This paper reviews the ways the Earth is used by astrobiologists: (i) by conducting planetary field analogue studies to investigate extant life from extreme environments, its metabolisms, adaptation strategies and modern biosignatures; (ii) by conducting planetary field analogue studies to investigate extinct life from the oldest rocks on our planet and its biosignatures; (iii) by exposing terrestrial samples to simulated space or planetary environments and producing a sample analogue to investigate changes in minerals, biosignatures and microorganisms. The European Space Agency (ESA) created a topical team in 2011 to investigate recent activities using the Earth as a tool for astrobiology and to formulate recommendations and scientific needs to improve ground-based astrobiological research. Space is an important tool for astrobiology (see Horneck et al. in Astrobiology, 16:201-243, 2016;Cottin et al., 2017), but access to space is limited. Complementing research on Earth provides fast access, more replications and higher sample throughput. The major conclusions of the topical team and suggestions for the future include more scientifically qualified calls for field campaigns with planetary analogy, and a centralized point of contact at ESA or the EU for the organization of a survey of such expeditions. An improvement of the coordinated logistics, infrastructures and funding system supporting the combination of field work with planetary simulation investigations, as well as an optimization of the scientific return and data processing, data storage and data distribution is also needed. Finally, a coordinated EU or ESA education and outreach program would improve the participation of the public in the astrobiological activities.

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“…Unfortunately a complex process such as the splash in saltation involves both the inertial mass (on impact) and the gravitational mass (during the trajectory) of the sand particulates. This makes this process impossible to entirely reproduce in a terrestrial laboratory and can probably only be studied through partial experimental simulation, modeling and observation in the respective gravitational field [Merrison et al 2007]. Wind tunnels involved in sand transport are typically of the order of a square meter cross section, several meters long and are constructed as boundary layer simulators with the use of (upstream) flow control to reproduce the correct surface boundary layer (and shear stress) [Young 1989].…”

Section: Aeolian Sand and Dust Transportmentioning

confidence: 99%

Environmental Wind Tunnels

Merrison¹

2011

Wind Tunnels

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Determination of the wind induced detachment threshold for granular material on Mars using wind tunnel simulations

Cited by 82 publications

References 42 publications

Simulating the interannual variability of major dust storms on Mars using variable lifting thresholds

Simulating the interannual variability of major dust storms on Mars using variable lifting thresholds

Earth as a Tool for Astrobiology—A European Perspective

Environmental Wind Tunnels

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