Discovery of dust devils vortices in Mars Pathfinder images by this study is direct evidence of a dust entrainment mechanism at work on Mars. Dust devils on Earth can entrain fine material from crusted as well as unconsolidated surfaces, even when forced-convection wind speeds are below threshold. Terrestrial dust devils are commonly “squat” V-shaped vortices lasting several minutes. Well developed vortices consist of an outer cylinder of high rotation (25 m/s), an Intermediate cylinder of moderate vertical lift (13 m/s), and a inner cylindrical core of low pressure (1.5% below ambient pressure) and elevated temperature (up to 20°C above ambient air temperature). Directly sampled dust devils on Earth were found to carry from 30 to over 2000 kg of soil. On average, the Eldorado Valley, NV, experienced 42 observable dust devils per summer day, each lofting over 200 kg for a daily total of 9 metric tonnes from this desert basin.; Spectral differencing techniques have enhanced five localized dust plumes against the general haze in Mars Pathfinder images acquired near midday, which are determined to be dust devils. Given interpreted geographic locations relative to the lander, the dust devils are 14 to 79 m wide, 46 to over 350 m tall, and travel over ground at 0.5 to 4.6 m/s. Their dust loading was approximately 7 × 10−5 kg/m3, relative to the general haze of 9 × 10−8 kg/m3. With an estimated vertical dust flux of 0.5 g m−2 s−1, total particulate transport of these Martian dust devils may have ranged from 2.2 kg for a small dust devil lasting 35 s to over 700 kg for a large plume of 400 s duration. Observed characteristics of these plumes are consistent with expectations based on theory and the lessons of terrestrial field studies. The increasingly apparent role of dust devils in the dust aeolian transport cycle may largely explain the continued concentration of the general Martian dust haze and perhaps the Initiation mechanism for global dust storms.
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机译：这项研究在火星探路者影像中发现了尘埃漩涡，这直接证明了在火星上存在尘埃夹带机制。即使强迫对流风速低于阈值，尘土也会从结s的和未固结的表面夹带细小的物质。地面尘埃通常是持续数分钟的“下蹲” V形漩涡。发达的涡流由高旋转的外圆柱体（<25 m / s），中等的垂直升力的中间圆柱体（<13 m / s）和低压的内圆柱芯（低于环境压力<1.5％）组成和高温（比环境温度高20°C）。直接取样的尘埃魔鬼携带了30到2000公斤的土壤。平均而言，内华达州埃尔多拉多山谷在每个夏季每天经历42次可观察到的沙尘暴，每个沙尘暴放下200公斤，每天从这个荒漠流域共排放9公吨。光谱差分技术已增强了五个局部尘埃羽，以抵御正午附近获取的火星探路者影像中的一般雾霾，这些影像被确定为尘土恶魔。给定相对于着陆器可解释的地理位置，尘埃的宽度为14至79 m，高度为46至350 m以上，并以0.5至4.6 m / s的速度在地面上传播。相对于一般雾度为9×10 −8 kg / m，它们的粉尘负荷约为7×10 −5 kg / m 3 3 。估计的垂直尘埃通量为0.5 g m-2 s-1，这些火星尘埃的总颗粒传输范围可能从持续35 s的小型尘埃魔鬼的2.2 kg到持续400 s的大烟羽的700 kg以上。这些羽状流的观测特征与基于理论和地面实地研究的教训的预期一致。尘埃在尘埃风尘运输周期中的作用日益明显，这在很大程度上可以解释整个火星尘埃霾的持续集中以及也许是全球沙尘暴的引发机制。
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