The Penetration of Solar Radiation Into Water and Carbon Dioxide Snow, With Reference to Mars
The Penetration of Solar Radiation Into Water and Carbon Dioxide Snow, With Reference to Mars
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DOI：
10.1029/2018je005771
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发表时间：
2019-02-01
影响因子：
4.8
通讯作者：
Lewis, S. R.
中科院分区：
文献类型：
--
作者：
Chinnery, H. E.;Hagermann, A.;Lewis, S. R.
太阳辐射穿透冰层的深度是了解行星表面结冰时表面-大气相互作用的一个重要因素。火星表面和地下都有水和二氧化碳冰。在高纬度地区，在秋季和冬季，二氧化碳冷凝形成季节性的极冠。这已经被模拟和观察到，部分发生在降雪中。随着雪的积累，地表的热特性发生了变化，无论其下的地表是岩石、风化层还是固体冰盖。这会导致反射率的变化（通常是增加），影响入射太阳能反射或透射到雪层表面以下的比例。光可以穿透这一层的深度是火星表面热传递模型中的一个重要参数，通常使用e-折叠尺度进行量化。我们在纯二氧化碳雪中首次测量了波长为300至1100 nm的e折叠尺度，同时还测量了水雪的新尺度。简明语言摘要固态温室效应与气候温室效应相似。它存在于对可见光半透明但对红外线不透明的固体材料中，例如冰。在火星上，雪和霜由水和二氧化碳冰形成。当太阳照射在雪或霜上时，一些光被漫反射，一些光透过雪粒，一些光被冰吸收。穿过材料的光的比例取决于其光学性质，这是其组成所独有的。然而，由于霜或雪的性质是非常小的颗粒状材料，大部分光在颗粒表面散射。在这项研究中，我们测量了水和二氧化碳雪的特定厚度的积雪可以传播的光量。这有助于确定有多少能量可以通过雪输送到下面的地面，从而使下面的物质升温。这意味着可以更准确地计算火星表面被雪和霜覆盖时的温度分布，从而深入了解在火星上观察到的不同表面过程。
The depth to which solar radiation can penetrate through ice is an important factor in understanding surface-atmosphere interactions for icy planetary surfaces. Mars hosts both water and carbon dioxide ice on the surface and in the subsurface. At high latitudes during autumn and winter carbon dioxide condenses to form the seasonal polar cap. This has been both modeled and observed to, in part, occur as snowfall. As snow accumulates, the thermal properties of the surface are changed, whether the underlying surface was rocky, regolith, or a solid ice sheet. This results in a change (usually increase) in albedo, affecting the proportion of the incident solar energy reflected, or transmitted below the surface of the snow layer. The depth to which light can penetrate through this layer is an important parameter in heat transfer models for the Martian surface and is often quantified using the e-folding scale. We present the first measurements of the e-folding scale in pure carbon dioxide snow for the wavelengths 300 to 1100nm alongside new measurements of water snow.Plain Language Summary The solid-state greenhouse effect is similar to the climatic greenhouse effect. It occurs in solid materials that are translucent to visible light, but opaque in the infrared, such as ices. On Mars, snow and frosts form from both water and carbon dioxide ice. When the Sun shines on the snow or frost, some light is diffusely reflected, some is transmitted through the snow grains, and some is absorbed by the ice. The proportion of light that travels through a material is dependent on its optical properties, which are unique to its composition. Owing, however, to the nature of frost or snow being a very small, granular material, much of the light is scattered at the grain surfaces. In this study we measured the amount of light that can travel through a snowpack of a particular thickness for both water and carbon dioxide snows. This helps determine how much energy can be transported through the snow to the ground below, which warms up the underlying material. This means that more accurate calculations can be made about the temperature profile of the Martian surface when covered in snow and frost, which gives insight into the different surface processes observed on Mars.