Quantified Aeolian Dune Changes on Mars Derived From Repeat Context Camera Images
Quantified Aeolian Dune Changes on Mars Derived From Repeat Context Camera Images
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DOI：
10.1029/2019ea000874
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发表时间：
2020-01-11
影响因子：
3.1
通讯作者：
Baird, Thomas
中科院分区：
文献类型：
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作者：
Davis, Joel M.;Grindrod, Peter M.;Baird, Thomas
风成系统在火星表面的大部分地区都很活跃，量化床型的活动对于了解现代和最近的火星环境非常重要。最近，迁移率和沙通量的沙丘和涟漪已被精确测量使用重复高分辨率成像科学实验（HiRISE）图像。然而，HiRISE覆盖范围有限，意味着只有一个小区域可以作为重复覆盖的目标。背景相机（CTX）图像，虽然空间分辨率较低，但具有更广泛的空间覆盖范围，这意味着沙丘迁移可以在更大的区域进行监测。我们使用时间序列，共配准CTX图像和数字高程模型来测量沙丘迁移率和沙通量在六个站点：尼利帕特拉，Meroe帕特拉，两个站点在赫歇尔陨石坑，麦克劳克林陨石坑，和Hellespontus蒙特斯。我们观察到沙丘位移的CTX图像在长期基线（7.5-11地球年; 4-6火星年）。之前已经使用HiRISE在所有这些站点测量了床型活动，我们使用HiRISE来验证我们的结果。我们的沙丘迁移率（0.2-1.1 m/EY）和沙通量（2.4-11.6 m（3）m（-1）EY-1）与HiRISE的测量结果相当。在监测沙丘迁移中使用CTX有优点（更广泛的空间覆盖，更快的处理时间）和缺点（涟漪无法解决，数字高程模型沙丘高度可能被低估）;未来HiRISE和CTX的结合使用可能是有益的。简明语言总结沙丘和涟漪存在于火星表面的大部分地区。从轨道卫星图像和表面上的漫游车观察到沙丘和涟漪的运动，这表明环境在不断变化。以前，高分辨率（亚米级）卫星图像一直用于跟踪沙丘和涟漪在地表的移动，这些沙丘和涟漪通常以每年高达数米的速度移动。然而，高分辨率图像的覆盖范围有限，这意味着只能对选定的地点进行监测。在这里，我们使用中等分辨率（米级）的卫星图像，它覆盖了更广泛的区域，作为一个测试案例，看看我们是否可以准确地测量沙丘的运动，这些沙丘通常有几百米长。我们选择了六个先前使用高分辨率图像测量的地点，以监测类似于10个地球年的时间。我们的研究结果表明，我们的沙丘迁移率一般比较好的高分辨率测量。今后综合使用中分辨率和高分辨率图像监测火星沙丘可能是有益的。
Aeolian systems are active across much of the surface of Mars and quantifying the activity of bedforms is important for understanding the modern and recent Martian environment. Recently, the migration rates and sand fluxes of dunes and ripples have been precisely measured using repeat High Resolution Imaging Science Experiment (HiRISE) images. However, the limited areal extent of HiRISE coverage means that only a small area can be targeted for repeat coverage. Context Camera (CTX) images, although lower in spatial resolution, have wider spatial coverage, meaning that dune migration can potentially be monitored over larger areas. We used time series, coregistered CTX images and digital elevation models to measure dune migration rates and sand fluxes at six sites: Nili Patera, Meroe Patera, two sites at Herschel crater, McLaughlin crater, and Hellespontus Montes. We observed dune displacement in the CTX images over long-term baselines (7.5-11 Earth years; 4-6 Mars years). Bedform activity has previously been measured at all these sites using HiRISE, which we used to validate our results. Our dune migration rates (0.2-1.1 m/EY) and sand fluxes (2.4-11.6 m(3) m(-1) EY-1) compare well to measurements made with HiRISE. The use of CTX in monitoring dune migration has advantages (wider spatial coverage, faster processing time) and disadvantages (ripples not resolved, digital elevation model dune heights may be underestimates); the future combined use of HiRISE and CTX is likely to be beneficial.Plain Language Summary Sand dunes and ripples are present across much of the surface of Mars. The motion of both dunes and ripples has been observed from orbital satellite images and rovers on the surface, which shows that the environment is constantly changing. Previously, high-resolution (submeter scale) satellite images have been used to track the movement of dunes and ripples across the surface, which generally move at rates of up to several meters per year. However, the limited coverage of high-resolution images means that only select sites can be monitored. Here we use medium resolution (meter scale) satellite images, which covers a much wider area, as a test case to see if we can accurately measure the movement of dunes, which are typically several hundred meters in length. We chose six sites that have previously been measured using high-resolution images to monitor of over periods of similar to 10 Earth years. Our results show that our dune migration rates generally compare well to the high-resolution measurements. The combined future use of medium and high-resolution images for monitoring dunes on Mars is likely to be beneficial.