Dust devils at White Sands Missile Range, New Mexico: 1. Temporal and spatial distributions

Abstract

a dust devil census was conducted at the Permanent High Explosive Test Site on White Sands Missile Range, New Mexico. In a 260-km 2 observation area, a total of 3134 dust devils were counted on 97 days (out of 112 observing days).Within the observation area, the dust devils were concentrated in a relatively small area and showed strong canrelation with roadways and other cleared areas. However, from the stunmet of 1986 to the spring of 1987, the center of activity shifted from a relatively undisturbed region to an area whose surface had been recently modified. This shift is attributed to changes in soil moisture and surface thermal properties. It is suggested that the co-location of the center of activity in 1987 with the modified surface is an example of inadvertent weather modification on a very local scale. The dust devils had a daily distribution very similar to that found by Sinclair (1969) in comparable terrain in the vicinity of Tucson, Arizona. The time of the first observed dust devil was very regular on days with dry surface conditions at sunrise and clear skies through the morning. The time of the first dust devil was delayed and the degree of activity reduced if precipitation had occurred on a previous day in the observation area. The production of dust devils often ended abruptly with the onset of an aftemoon thundershower in the observation area. l. INTRODUCrION An observational study of dust devils was conducted during late spring and summer 1986 and spring 1987 at a site on White Sands Missile Range (WSMR) in south-central New Mexico. The goals of this study were (1) to determine spatial and temporal distributions of dust devils in a 260-km 2 region and (2) to relate these to background meteorology. Since the first goal involved the counting of a large number of dust devils, this portion of the study is termed a "dust devil census" after Sinclair [1969].The pro'poses of this initial paper are twofold. The first is to present spatial and temporal distributions of dust devils determined from the census data. The second is to discuss apparent relationships between the dust devil observations, general regional meteorology, and local surface conditions. Novel aspects of this census are the large area considered, the long durations of the observing periods, and the large number of dust devils observed. C•ssus LOCATION2.1. The Site The census was conducted in the northern section of WSMR at the Permanent High Explosive Test Site (PHETS) of the Defense Nuclear Agency (DNA). PHETS is located along the eastern edge of a broad basin, commonly termed the Jomado del Muerto, that is part of the climatological division termed the Central Valley of New Mexico [Houghton, 1972]. In terms of general climate and vegetative cover, the region can be classified as medium elevation, semi-arid ranch land. (This portion of WSMR is similar in its surface and climatic features to the area around Tucson, Arizona, at the time S/nc/air [1969] conducted his census.) For the census, the designated observation area was the 13-kil...

Dust devil speeds, directions of motion and general characteristics observed by the Mars Express High Resolution Stereo Camera

“…The larger parts of the detected dust devils have a forward motion range from a few meters per second to 15 m/s (Table 1). These values are in good agreement with observations of dust devils on Earth (Sinclair, 1969;Snow and McClelland, 1990) and with predictions for Mars (Ryan and Lucich, 1983;Metzger et al, 1999;Rennó et al, 1998;Ferri et al, 2003). The average speed for 74 dust devils, however, was 23.1 m/s, with a range from 15.0 to ∼59 m/s ( Table 1).…”

“…The dust devil distribution in the southern hemisphere has a clear peak during southern summer, consistent with Whelley and Greeley (2006 and in press), with very few detections in the other seasons ( Figure 2). All dust devils detected by HRSC occurred at noon or afternoon (Figure 3), as on Earth (Sinclair, 1969;Snow and McClelland, 1990) and in previous Mars studies (Wennmacher et al, 1996;Balme et al, 2003;. The data shows a significant peak between 1400 and 1500 hours.…”

“…Former investigations concerning dust devils on Earth and Mars assume that high ambient wind speeds suppress dust devil formation and evolution and that measurements of high forward motions are due to measurement errors (Snow and McClelland, 1990). Combining existing theory and simulations (Kanak, 2006;Michaels and Rafkin, 2004;Rennó et al, 2000;Rennó and Bluestein, 2001) with the results from HRSC and Spirit (<1-21 m/s) leads to the suggestion that dust devil formation is not suppressed by high wind speeds.…”

“…They contribute to Martian weather by dust entrainment, which influences atmosphere temperature, and lead to surface changes by removing thin layers of dust, causing albedo changes (Malin and Edgett, 2001). Studies on Earth (Ives, 1947;Ryan, 1972;Snow and McClelland, 1990;Metzger, 2003) and Mars (Cantor et al, 2006; Balme et…”

Effects of Ambient Rotation on Dust Devils

“…As they are visualized by lifted dust particles, many observational studies have examined their structure and characteristics (e.g., Sinclair 1969;Hess and Spillane 1990;Snow and McClelland 1990;Bluestein et al 2004;Oke et al 2007), revealing that dust devils usually have no preferred direction of rotation and implying that the earth's rotation has a negligible effect on the vortex dynamics (Sinclair 1965;Carroll and Ryan 1970). In the past decade, dust devils have been also studied by means of large eddy simulations (LESs) (Kanak et al 2000;Toigo et al 2003;Kanak 2005;Ito et al 2010;Ohno and Takemi 2010a;Ohno and Takemi 2010b;Gheynani and Taylor 2010).…”