An expression for saltation threshold – the minimum wind speed required to initially saltate particles – is necessary for modeling aeolian processes on Earth and other bodies. Analysis of a compilation of experimental data led to the conclusion that this threshold is a function of the ratio of the density of the particle to that of the entraining fluid (ρ_p/ρ), and to a curve for the dimensionless threshold parameter, A(ρ_p/ρ). Whereas data of low-density ratio and of high-density ratio conditions show constant A values, the single dataset used to define the transitional region of the curve shows a range of values. To revisit this transitional region, we collect new freestream threshold data at 1–20 bars (1–20 × 10⁵ Pa) with particles 150–1000 µm in diameter and having densities 400–3300 kg/m³ using the Titan Wind Tunnel. From these new data spanning a range of intermediate density ratios, we calculate friction wind speeds and values for A(ρ_p/ρ). We filter our threshold data for the same conditions (particle diameter > 200 µm, particle Reynolds number > 10) as in previous work and combine them with previously published data to derive a new density ratio curve with the same form as the previous expression. This new curve of A(ρ_p/ρ), with different parameter values and including uncertainties, confirms the slope in the transitional region between low- and high-density ratios, though giving slightly higher values for A. This work offers improved prediction of threshold wind speeds under thicker-than-terrestrial atmospheres on other solar or extrasolar planets, while also suggesting current challenges to accurate experimental simulation of aeolian transport under such conditions.

为了模拟地球和其他物体上的风成过程，必须使用盐化阈值（最初盐化颗粒所需的最小风速）的表达式。得出的结论的实验数据的汇编的分析，这阈值是所述颗粒的密度使之与比的函数的输送流体（ρ _p /ρ），并为无量纲阈值参数，曲线甲（ρ _p /ρ）。低密度比和高密度比条件的数据显示恒定的A值，而用于定义曲线过渡区域的单个数据集则显示一个值范围。为了重温这个过渡区域，我们以1-20 bar（1-20×10 ⁵ Pa）直径为150–1000 µm的颗粒，密度为400–3300 kg / m ^3（使用Titan风洞）。从这些新数据跨越范围中间密度比，我们可以计算出摩擦风速和值阿（ρ _p /ρ）。我们在与以前的工作相同的条件（粒径> 200 µm，雷诺数> 10）下过滤阈值数据，并将其与先前发布的数据结合起来，以得出具有与先前表达式相同形式的新密度比曲线。这种新的曲线甲（ρ _p /ρ）中，用不同的参数值，并且包括不确定性，证实了低和高密度比之间的过渡区域中的斜率，虽然给出稍高值一。这项工作提供了改进的对其他太阳或太阳系外行星比地球大气层厚的阈值风速的预测，同时也提出了在这样的条件下进行精确的风沙传输实验的当前挑战。