Evolution of south seasonal cap during Martian spring: Insights from high‐resolution observations by HiRISE and CRISM on Mars Reconnaissance Orbiter
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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火星春季南季冠的演变：火星勘测轨道器上 HiRISE 和 CRISM 高分辨率观测的见解
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发表时间：
2011
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影响因子：
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通讯作者：
Y. Langevin
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作者：
A. Pommerol;G. Portyankina;N. Thomas;K. Aye;C. Hansen;M. Vincendon;Y. Langevin
[1]我们使用的数据从高分辨率成像科学实验（HiRISE）相机和紧凑型侦察成像光谱仪火星（CRISM）成像光谱仪机载火星侦察轨道飞行器遵循的外观和组成的演变12个地区的南极层状存款从春季到夏季的时间。挥发层的演化分为三个阶段：在Ls = 190° ~ 210 °时，CO2带强度和CO2吸收带强度均减小;在Ls = 240° ~ 260 °时，CO2带强度和CO2吸收带强度均显著增大;相比之下，水冰带显示出更单调的减少。同时获得的HiRISE彩色图像与CRISM数据的分析允许这种演变的合理解释。在早春（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。小尺度地形通过允许在斜坡上收集更多的太阳能来控制射流的存在和位置。来自尘扇的颗粒升温并下沉通过CO2层，导致在Ls = 190°-210°附近的风扇位置处的蓝色。随着大气变暖，冰层表面升华并释放出灰尘和水，导致其变亮。这一进程的最后阶段是逐步解冻，形成冻区和解冻区的拼凑。
[1] 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.