DOI: 10.5281/zenodo.18469700
title: Threshold Velocity of Wind-Blown Sand under Jezero Crater–Like Martian Conditions

description: 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.