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首页> 外文期刊>Journal of geophysical research. Planets >Evolution of south seasonal cap during Martian spring: Insights from high‐resolution observations by HiRISE and CRISM on Mars Reconnaissance Orbiter
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Evolution of south seasonal cap during Martian spring: Insights from high‐resolution observations by HiRISE and CRISM on Mars Reconnaissance Orbiter

机译：火星春季南半球季节上限的演变：HiRISE和CRISM对火星侦察轨道器进行高分辨率观测的结果

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摘要

We use data from the High Resolution Imaging Science Experiment (HiRISE) camera and the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) imaging spectrometer onboard the Mars Reconnaissance Orbiter to follow the evolution of the appearance and composition of 12 regions of the south polar layered deposits from spring to summer time. We distinguish three steps in the evolution of the volatile layer: a decrease of both CO2 band strength and albedo until Ls = 190°–210°, a significant increase in both until Ls = 240°–260° and finally a rapid decrease until the complete defrosting of the ground. In contrast, the water ice band displays a more monotonic decrease. Analysis of HiRISE color images acquired simultaneously with CRISM data allows a plausible interpretation of this evolution. In early springtime (Ls < 200°), intense jet activity results in deposition of fans of large mineral grains and a wide spatial distribution of fine grains. The small‐scale topography controls the presence and location of the jets by allowing more solar energy to be collected on slopes. Grains from the dust fans warm and sink through the CO2 layer, resulting in a bluish color at the locations of the fans around Ls = 190°–210°. As the atmosphere warms up, the surface of the ice layer sublimes and releases dust and water, resulting in its brightening. The last phase of the process consists in a progressive defrosting resulting in a patchwork of frozen and unfrozen areas.
机译：我们使用来自高分辨率成像科学实验（HiRISE）相机和火星侦察轨道飞行器上的火星紧凑侦察成像光谱仪（CRISM）成像光谱仪的数据来追踪南极分层沉积物12个区域的外观和组成演变从春季到夏季。我们区分了挥发性层演化的三个步骤：CO2谱带强度和反照率均下降，直到Ls = 190°–210°; Ls = 240°–260°时两者都显着增加，最后迅速下降，直到Ls = 240°–260°。彻底除霜。相反，水冰带显示出更单调的下降。与CRISM数据同时采集的HiRISE彩色图像的分析可以合理地解释这种演变。在春季的早期（Ls <200°），强烈的射流活动导致大矿物颗粒的扇形沉积和细颗粒的广泛空间分布。小规模的地形通过允许在斜坡上收集更多的太阳能来控制喷流的存在和位置。尘埃风扇发出的颗粒变热并沉入CO2层，导致风扇的Ls = 190°–210°左右的位置呈蓝色。随着大气变暖，冰层的表面升华并释放出灰尘和水，从而使其变亮。该过程的最后一个阶段是进行逐步除霜，导致冰冻和未冰冻区域拼凑而成。

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