Mathematics – Logic
Scientific paper
Dec 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufm.p42c..05p&link_type=abstract
American Geophysical Union, Fall Meeting 2011, abstract #P42C-05
Mathematics
Logic
[0343] Atmospheric Composition And Structure / Planetary Atmospheres, [3307] Atmospheric Processes / Boundary Layer Processes, [5405] Planetary Sciences: Solid Surface Planets / Atmospheres, [6225] Planetary Sciences: Solar System Objects / Mars
Scientific paper
Dust devils are particle-loaded vertical convective vortices commonly observed on Earth and especially Mars. Qualitative estimates of terrestrial dust devil frequency based upon visual field surveys have varied by several orders of magnitude. We will present the results of our quantitative characterization of the size-frequency distribution (SFD) of terrestrial dust devils, which utilizes stereo photography to calculate dust devil diameters via parallax displacement. In 2009, we conducted field campaigns in Eloy, Arizona and Eldorado Valley, Nevada to survey terrestrial dust devils: the latter site was revisited in 2010. During each survey period, at least two and usually three observers were positioned at spotter stations located approximately 100 m apart, thereby allowing triangular study areas (bounded by three meteorological masts) of A = 0.83 sq. km and A = 0.55 sq. km to be surveyed in Eloy and Eldorado Valley, respectively. Each spotter station was equipped with a tripod-mounted, weatherproof digital camera: whenever possible, any dust devils observed within the study area were photographed simultaneously by camera operators in radio contact. All dust devils observed within the survey sites were assigned a qualitative diameter estimate (i.e., Tiny/Small/Medium/Large) by a third spotter positioned near the center of the study area. Thus even if small dust devils occurred that existed too fleetingly to be photographed, they were still recorded. Methodology: The positions of both survey tripods were measured to ~ 0.5 m precision using GPS. In addition, a full 360-degree panorama was generated from each survey position, corrected for lens distortion, and then imported into a GIS. The photographs of dust devils from each camera are then also incorporated into the GIS and aligned against the corresponding background panorama. The width and center points of each dust devil are then digitized and its bearings and angular width outputted from the GIS, together with the time it was photographed. Finally, using simple geometry, the position and width of each dust devil is calculated, converted into UTM coordinates and presented in a map-projected format. Initial results show that our methodology is robust and that reliable data for size and position of dust devils can be extracted. Altogether, we were able to successfully stereo photograph approximately 40% of the more than 1000 dust devils that we observed within the study areas during the three field campaigns. We will use the quantitative parallax-derived dust devil diameter measurements to assess the accuracy of our qualitative size estimates, accounting for a variety of factors such as distance, speed, duration, apparent dustiness, and number of observers. Our analysis will not only yield a more comprehensive SFD for terrestrial dust devils, but will also help constrain SFD parameterizations of Martian dust devils based on orbiter and lander observations.
Balme Matthew R.
Elliott M. H.
Fenton Lori K.
Metzger Steffen
Michaels Timothy I.
No associations
LandOfFree
A Quantitative Assessment of the Size-Frequency Distribution of Terrestrial Dust Devils, Comparison with Qualitative Estimates, and Applications to Mars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with A Quantitative Assessment of the Size-Frequency Distribution of Terrestrial Dust Devils, Comparison with Qualitative Estimates, and Applications to Mars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A Quantitative Assessment of the Size-Frequency Distribution of Terrestrial Dust Devils, Comparison with Qualitative Estimates, and Applications to Mars will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-871839