Sensitivity of modeled far‐IR radiation budgets in polar continents to treatments of snow surface and ice cloud radiative properties
Sensitivity of modeled far‐IR radiation budgets in polar continents to treatments of snow surface and ice cloud radiative properties
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极地大陆远红外辐射预算模型对雪面和冰云辐射特性处理的敏感性
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
M. Flanner
中科院分区：
文献类型：
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作者：
Xiuhong Chen;Xianglei Huang;M. Flanner
虽然大多数一般环流模型在长波辐射处理中假设光谱独立的表面发射率和非散射云，但冰折射率的光谱变化表明，在远红外区域，雪表面发射率可能变化很大，并且冰云可能导致不可忽略的散射。这些影响对于高海拔极地大陆更为重要，那里干燥寒冷的大气在远红外区域并非不透明。我们进行的敏感性研究表明，在南极高原的冬季，包括辐射传输计算中的雪表面光谱发射率和冰云散射，减少了大气顶部和地表的净向上远红外通量。月平均全天远红外通量减少的幅度从 0.72 到 1.47 Wm−2 不等，云散射和表面光谱发射率的贡献也相当。这种减少对雪粒和云颗粒的大小也很敏感。
While most general circulation models assume spectrally independent surface emissivity and nonscattering clouds in their longwave radiation treatment, spectral variation of the index of refraction of ice indicates that in the far IR, snow surface emissivity can vary considerably and ice clouds can cause nonnegligible scattering. These effects are more important for high‐elevation polar continents where the dry and cold atmosphere is not opaque in the far IR. We carry out sensitivity studies to show that in a winter month over the Antarctic Plateau including snow surface spectral emissivity and ice cloud scattering in radiative transfer calculation reduces net upward far‐IR flux at both top of atmosphere and surface. The magnitudes of such reductions in monthly mean all‐sky far‐IR flux range from 0.72 to 1.47 Wm−2, with comparable contributions from the cloud scattering and the surface spectral emissivity. The reduction is also sensitive to sizes of both snow grains and cloud particles.