Threshold Velocity of Wind-Blown Sand under Jezero Crater–Like Martian Conditions

Supporting Information for “Threshold Velocity of Wind-Blown Sand under Jezero Crater–Like Martian Conditions” Introduction This supporting information provides the underlying datasets, raw imagery, and analysis code used to generate the key findings presented in the main text. The files include tabulated particle size distribution data (Figure 2), quantitative morphological parameters for terrestrial and Martian grains (Figure 5), and the recalibrated threshold friction velocity datasets compared against historical studies and variable pressure experiments (Figure 6). Additionally, the MATLAB source code used for image segmentation and shape factor calculation is provided to ensure reproducibility. Data Set S1. Particle Size Distribution Data (Figure 2) This dataset (Figure_2_Data.xlsx) contains the laser diffraction particle size analysis results for the JMSS-1 simulant samples used in the wind tunnel experiments. The data presents the cumulative volume percentage (Volume %) as a function of particle diameter ($D_p$ in \textmu m) for four distinct sieving grades: 52.33 μm: Fine-grained component. 93.25 μm: Medium-grained component (closest to the optimal saltation size). 150.45 μm: Coarse-grained component. 277.55 μm: Very coarse-grained component. These distributions were used to characterize the sorting and mean diameter of the bed materials tested in the low-pressure wind tunnel. Data Set S2. Morphological Parameter Data (Figure 5) This dataset (Figure_5_Data.xlsx) provides the raw quantitative shape factor measurements for individual particles, as summarized in the boxplots of Figure 5. The dataset includes three primary morphological metrics: Circularity: Measuring the degree of roundness ($4\pi \times \text{Area} / \text{Perimeter}^2$). Aspect Ratio: The ratio of the major axis to the minor axis of the fitted ellipse. Solidity: The ratio of the particle area to the area of its convex hull. Measurements are categorized into three lithological groups for comparison: Sand: Terrestrial desert sand grains (Tengger Desert). JMSS-1: Mechanically crushed Martian soil simulant. Jezero Crater: Martian regolith grains analyzed from Perseverance SuperCam RMI images (Sol 315). Data Set S3. Threshold Friction Velocity Comparisons and Pressure Dependence (Figure 6) This dataset (Figure_6_Data.xlsx) contains the numerical values for the threshold friction velocity ($u_{*t}$) analysis. It is divided into three sections: Model Comparison: Predicted $u_{*t}$ vs. grain size curves for the standard Earth-parameterized Shao & Lu (2000) model versus the recalibrated Martian-parameterized model derived in this study. Historical Validation: Digitized experimental data points from previous low-pressure studies, including Swann et al. (2020) at 800 Pa and Greeley et al. (1976) at various pressures (790 Pa, 650 Pa, 530 Pa). Pressure Dependence Experiments: Experimental measurements of $u_{*t}$ for 127 \textmu m particles under varying chamber pressures (ranging from $\sim$700 Pa to $\sim$1500 Pa), validating the inverse relationship between atmospheric density and entrainment threshold. File S1. Jezero Crater Sand Sample Images A collection of high-resolution image crops derived from the SuperCam Remote Micro-Imager (RMI) on board the Perseverance rover (Sol 315). These raw images were used as the input for the morphological analysis of Martian grains. Software S1. Shape Factor Analysis Code A MATLAB script (shape_factor_analyze_code.m) developed to process particle images. The code performs the following functions: Image binarization and segmentation. Boundary extraction of individual grains. Calculation of 2D shape parameters (Circularity, Aspect Ratio, and Solidity). This script allows for the replication of the morphological methodology applied to both the laboratory samples and the Martian RMI imagery.《杰泽罗撞击坑类火星环境下风沙起动阈值风速》补充材料 引言 本补充材料提供了生成正文中核心结论所依托的原始数据集、未处理影像及分析代码。所附文件包含：制表格式的颗粒粒径分布数据（对应图2）、地球与火星颗粒的定量形貌参数（对应图5），以及经重新校准的阈值摩擦速度（threshold friction velocity）数据集（该数据集与既往研究及变压实验结果进行了对比，对应图6）。此外，本文还提供了用于图像分割与形状因子计算的MATLAB (MATLAB) 源代码，以确保研究可复现。 数据集S1：颗粒粒径分布数据（图2） 本数据集（文件名为Figure_2_Data.xlsx）包含风洞实验所用JMSS-1火星土壤模拟物样品的激光衍射粒度分析（laser diffraction particle size analysis）结果。数据展示了4个不同筛分级别的颗粒直径（$D_p$，单位为微米μm）对应的累积体积百分比（体积占比，Volume %）： 52.33 μm：细粒组分 93.25 μm：中粒组分（最接近最优跃移粒径） 150.45 μm：粗粒组分 277.55 μm：极粗粒组分 上述粒径分布被用于表征低压风洞实验中床面物料的分选性与平均粒径。 数据集S2：形貌参数数据（图5） 本数据集（文件名为Figure_5_Data.xlsx）提供了单颗粒的原始定量形状因子测量结果，对应图5的箱线图汇总内容。数据集包含3项核心形貌指标： 圆度（Circularity）：表征颗粒圆润程度，计算公式为$4pi imes ext{面积} / ext{周长}^2$ 长短轴比（Aspect Ratio）：拟合椭圆的长轴与短轴之比 密实度（Solidity）：颗粒面积与其凸包（convex hull）面积的比值 测量结果分为3类岩性组以进行对比： 沙漠砂（Sand）：地球沙漠砂颗粒（取自腾格里沙漠） JMSS-1：机械破碎型火星土壤模拟物 杰泽罗撞击坑颗粒（Jezero Crater）：基于"毅力号（Perseverance）"SuperCam远程显微成像仪（Remote Micro-Imager，RMI）影像（Sol 315）分析得到的火星风化层颗粒 数据集S3：阈值摩擦速度对比与压力依赖性（图6） 本数据集（文件名为Figure_6_Data.xlsx）包含阈值摩擦速度（$u_{*t}$）分析的数值数据，分为3个部分： 模型对比：标准地球参数化的Shao & Lu（2000）模型与本研究重新校准的火星参数化模型的预测$u_{*t}$-颗粒尺寸曲线对比 历史验证：既往低压实验的数字化实验数据点，包括Swann等人（2020）在800 Pa下的实验数据，以及Greeley等人（1976）在不同压力（790 Pa、650 Pa、530 Pa）下的实验数据 压力依赖性实验：127 μm颗粒在不同舱室压力（约700 Pa至1500 Pa）下的$u_{*t}$实测值，验证了大气密度与颗粒起动阈值之间的负相关关系 文件S1：杰泽罗撞击坑砂样品影像 本文件集合包含从"毅力号"漫游车搭载的SuperCam远程显微成像仪（RMI）获取的高分辨率影像裁剪图（Sol 315）。这些未处理影像被用作火星颗粒形貌分析的输入数据。 软件S1：形状因子分析代码 本文件为用于处理颗粒影像的MATLAB脚本（shape_factor_analyze_code.m），可实现以下功能： 影像二值化与分割 单颗粒边界提取 二维形状参数（圆度、长短轴比、密实度）计算 该脚本可复现针对实验室样品与火星RMI影像的形貌分析流程。