Extensive lava flows are found in the equatorial region of Mars, shaping the surface in a very distinct way. In radar images (at the decimeter scale), these flows are bright, with circular polarization ratios greater than one. This is a typical characteristic of extremely rough, blocky lava flows on Earth. Although the source of the extreme dm-scale roughness of Martian lava flows is unknown, their surface roughness can be constrained at the meter scale in an effort to infer their emplacement style. Here, we utilized high-resolution HiRISE images of Mars to construct digital terrain models of 35 lava flows, and measure their surface roughness parameters at a scale never before examined. Our results show that at the meter scale, Martian lava flows are smoother than blocky flows seen on Earth, and similar in roughness to terrestrial pāhoehoe and rubbly flows, as well as young lunar lava flows. However, these latter flows are much smoother at the decimeter scale than Martian lava flows. The differences observed in the surface roughness of Martian lava flows compared to analog lava flows on Earth and the Moon might be the result of: (1) the differences in the emplacement style of the lava flows, and/or (2) the differences in post-emplacement modification processes on the surface of the lava flows.

在火星赤道区域发现大量的熔岩流，以非常不同的方式塑造了地表。在雷达图像（以分米为单位）中，这些流是明亮的，圆极化率大于1。这是地球上极其粗糙，块状的熔岩流的典型特征。尽管火星熔岩流的极端dm级粗糙度的来源是未知的，但可以推断出它们的表面粗糙度在米级以试图推断其安置方式。在这里，我们利用火星的高分辨率HiRISE图像构建了35个熔岩流的数字地形模型，并以前所未有的规模测量了其表面粗糙度参数。我们的结果表明，在米级，火星熔岩流比地球上看到的块状流更光滑，其粗糙度类似于陆地的phoehoe和碎石流以及年轻的月球熔岩流。但是，这些后流在分米尺度上要比火星熔岩流平滑得多。与地球和月球上模拟熔岩流相比，火星熔岩流表面粗糙度的差异可能是由于以下原因造成的：（1）熔岩流的放置方式不同，和/或（2）熔岩流表面的置入后改性过程。