Saltation is the major particle movement type in wind erosion process. Saltating sand grains can rebound up to tens of times larger in length and height over hard surface (such as gravel surface) than over loose sand surface. Gravels usually have different faces, causing distinct response of the impacting grains, but the effects of the grain and gravel-surface contact angle on grain rebound are not yet well quantified. We performed full-range controlled experiments of grain saltation using different contact angles, grain sizes and impact speeds in still air, to show that contact angle increases the height of representative saltation path but decreases particle travel length. The results were compared with outputs from the COMprehensive numerical model of SALTation (COMSALT). Large saltation height of 4.8 m and length of 9.0 m were recorded. The maximum and representative saltation height over the gravel surface were found to be about 4.9 times and 12.8 times those over the loose sandy surface, respectively. The maximum saltation length may be reduced by 58% and the representative saltation height may be increased by 77% as contact angle increases from 20° to 40°. We further showed that the collision inertia contributes 60% of the saltation length, and wind contributes to the other 40%. These quantitative findings have important implications for modeling saltation trajectory over gravel surface.

盐渍化是风蚀过程中主要的颗粒运动类型。盐渍砂粒在坚硬表面（如砾石表面）上的回弹长度和高度比在松散的沙子表面上大几十倍。砾石通常具有不同的面，导致撞击颗粒的不同响应，但颗粒和砾石表面接触角对颗粒回弹的影响尚未得到很好的量化。我们在静止空气中使用不同的接触角、颗粒大小和冲击速度进行了颗粒跃迁的全范围控制实验，以表明接触角增加了代表性跃迁路径的高度，但减少了颗粒行进长度。将结果与盐化综合数值模型 (COMSALT) 的输出进行比较。记录了 4.8 m 的大跃移高度和 9.0 m 的长度。砾石表面的最大和代表性跃移高度分别是松散砂质表面的 4.9 倍和 12.8 倍。随着接触角从 20° 增加到 40°，最大跃迁长度可减少 58%，代表性跃迁高度可增加 77%。我们进一步表明碰撞惯性贡献了跳跃长度的 60%，而风贡献了另外 40%。这些定量发现对模拟砾石表面的跃移轨迹具有重要意义。随着接触角从 20° 增加到 40°，最大跃迁长度可减少 58%，代表性跃迁高度可增加 77%。我们进一步表明碰撞惯性贡献了跳跃长度的 60%，而风贡献了另外 40%。这些定量发现对模拟砾石表面的跃移轨迹具有重要意义。随着接触角从 20° 增加到 40°，最大跃迁长度可减少 58%，代表性跃迁高度可增加 77%。我们进一步表明碰撞惯性贡献了跳跃长度的 60%，而风贡献了另外 40%。这些定量发现对模拟砾石表面的跃移轨迹具有重要意义。