MATADOR 2002: A pilot field experiment on convective plumes and dust devils

Abstract

[1] Recent research suggests that mineral dust plays an important role in terrestrial weather and climate, not only by altering the atmospheric radiation budget, but also by affecting cloud microphysics and optical properties. In addition, dust transport and related Aeolian processes have been substantially modifying the surface of Mars. Dusty convective plumes and dust devils are frequently observed in terrestrial deserts and are ubiquitous features of the Martian landscape. There is evidence that they are important sources of atmospheric dust on both planets. Many studies have shown that on a small scale, dust sourcing is sensitive to a large number of factors, such as soil cover, physical characteristics, composition, topography, and weather. We have been doing comparative studies of dust events on Earth and Mars in order to shed light on important physical processes of the weather and climate of both planets. Our 2002 field campaign showed that terrestrial dust devils produce heat and dust fluxes two and five orders of magnitude larger than their background values. It also showed that charge separation within terrestrial dust devils produces strong electric fields that might play a significant role in dust sourcing. Since Martian dust devils and dust storms are stronger and larger than terrestrial events, they probably produce even stronger fluxes and electric fields.

Applications of Electrified Dust and Dust Devil Electrodynamics to Martian Atmospheric Electricity

“…Large E-fields like those measured in situ in terrestrial dust devils have been found which exceed 50 kV m −1 Renno et al 2004;Jackson and Farrell 2006). These same electrical convective features placed in the low pressure Martian atmosphere are expected to initiate atmospheric breakdown.…”

“…In the centre of a convective feature, the grains become stratified in the upward flow of warm air. Small negative grains tend to lift upward and large positive grains remain lower in such features, giving rise to the large-scale dipole moment and E-field like that measured within terrestrial dust devils (Freier 1960;Crozier 1964;Renno et al 2004;Jackson and Farrell 2006). The dust load for a nominal terrestrial dust devil has been estimated to be up to ∼10 −3 kg m −3 (Metzger et al 2011).…”

“…Based on this sand electrification work electric fields have been predicted to be generally less than 50 kV m −1 and typically a few kV m −1 (Bo et al 2013a(Bo et al , 2013b, this is below values at which significant effects would be expected on saltation and below (upper limit for) value measured in the field Schmidt et al 1998;Renno et al 2004). It should be noted however, that the models applied did not include dust entrainment, i.e.…”

“…5) suggest that an electron avalanche and collisional plasma can be created when dust storm E-fields stress the low pressure CO 2 gas. (3) Measurements in terrestrial desert environments reveal that dust devils and dust features can generate large electric fields (Freier 1960;Crozier 1964;Renno et al 2004;Jackson and Farrell 2006;Seran et al 2013;Esposito et al 2015Esposito et al , 2016. If this same electrical generator process occurred in a lower pressure atmosphere (like that at Mars), there would be the initiation of enhanced electron impact ionization and atmospheric breakdown.…”

“…The results reported here are from measurements of the electric field at 3 m above the ground. The PM2.5 aerosol concentration is measured at approximately 3.5 m above the ground, and saltation is measured at 7 cm above the ground also indicating upward pointing electric fields in dust devils (e.g., Renno et al 2004).…”