标题： 关于尘卷风直径、出现率和活动性 显示英文标题

标题： On Dust Devil Diameters, Occurrence Rates, and Activity

摘要： 作为一种在地球和火星上都会出现的现象，尘卷风的直径有助于确定两者向大气中注入的灰尘量——对于给定的尘埃通量密度（单位面积单位时间提升的灰尘），更宽的尘卷风会将更多的灰尘带入空气中。 然而，决定尘卷风直径的因素$D$以及它可能与周围环境条件的关系仍然不清楚。 此外，估算具有不同直径的尘卷风群体对大气尘埃预算的贡献需要对微分直径分布进行准确评估，但仍有大量工作尚未揭示最佳表示方式或解释其物理基础。 在本研究中，我们提出该分布遵循幂律 $\propto D^{-5/3}$，并提供了一个简单的物理解释来说明为什么该分布呈现这种形式。 通过拟合几项研究中报告的火星尘卷风直径分布，我们表明来自几项研究的数据支持这一提出的形态。 利用一个将尘卷风视为热力学热机的先前模型，我们还表明尘卷风的面积密度（单位面积的数量）$N_0$与它们的热力学效率 $\eta$和感热通量 $F_{\rm s}$的乘积成比例，如 $N_0 \propto \eta F_{\rm s}$所示。 显示英文摘要

摘要： As a phenomenon that occurs on Earth and on Mars, the diameter of a dust devil helps determine the amount of dust the devil injects into the atmosphere for both worlds -- for a given dust flux density (dust lifted per area per time), a wider devil will lift more dust into the air. However, the factors that determine a dust devil's diameter $D$ and how it might relate to ambient conditions have remained unclear. Moreover, estimating the contribution to an atmospheric dust budget from a population of dust devils with a range of diameters requires an accurate assessment of the differential diameter distribution, but considerable work has yet to reveal the best representation or explain its physical basis. In this study, we propose that this distribution follows a power-law $\propto D^{-5/3}$ and provide a simple physical explanation for why the distribution takes this form. By fitting diameter distributions of martian dust devil diameters reported in several studies, we show that the data from several studies support this proposed form. Using a previous model that treats dust devils as thermodynamic heat engines, we also show that the areal density of dust devils (number per unit area) $N_0$ scales with the product of their thermodynamic efficiency $\eta$ and the sensible heat flux $F_{\rm s}$ as $N_0 \propto \eta F_{\rm s}$.