Quantifying bioalbedo: a new physically based model and discussion of empirical methods for characterising biological influence on ice and snow albedo
Quantifying bioalbedo: a new physically based model and discussion of empirical methods for characterising biological influence on ice and snow albedo
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DOI：
10.5194/tc-11-2611-2017
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发表时间：
2017-11-17
期刊：
影响因子：
5.2
通讯作者：
Tranter, Martyn
中科院分区：
文献类型：
--
作者：
Cook, Joseph M.;Hodson, Andrew J.;Tranter, Martyn
生物杂质对冰雪的暗化效应被认为是对陆地雪、海冰、冰川和冰盖表面能量平衡的控制。随着人们对了解气候变化对冰雪过程的影响的兴趣越来越高，量化生物杂质对冰雪过程的影响及其随时间的演变是一个快速增长的研究领域。然而，严格的量化bioadhesido仍然难以捉摸，因为难以分离的生物贡献冰adhesido的无机杂质和可变的光学性质的冰本身。因此，从空中/轨道平台获得的反射率数据中分离出生物特征尚未实现，即使在有地面生物测量数据的情况下也是如此。本文提供了特定于细胞的光学特性，需要模拟的光谱特征和宽带变暗的冰。应用辐射传输理论，这些特性提供了将生物和冰川学地面测量与遥感反射率数据联系起来所需的物理基础。使用这些新功能，我们确认生物杂质可以影响冰的生物量，然后我们确定了在现场测量生物量的10个挑战，目的是改进未来的实验设计，以更好地量化生物量反馈。这些挑战是（1）术语上的模糊性，（2）表征雪或冰的光学性质，（3）表征太阳辐照度，（4）确定细胞的光学性质，（5）测量生物量，（6）表征细胞的垂直分布，（7）表征非生物杂质，（8）表面各向异性，（9）测量间接光反馈，（10）测量和仪器配置。本文旨在为广大冰川学家和生物学家提供辐射传输和辐射通量的概述，以支持未来的实验设计。
The darkening effects of biological impurities on ice and snow have been recognised as a control on the surface energy balance of terrestrial snow, sea ice, glaciers and ice sheets. With a heightened interest in understanding the impacts of a changing climate on snow and ice processes, quantifying the impact of biological impurities on ice and snow albedo ("bioalbedo") and its evolution through time is a rapidly growing field of research. However, rigorous quantification of bioalbedo has remained elusive because of difficulties in isolating the biological contribution to ice albedo from that of inorganic impurities and the variable optical properties of the ice itself. For this reason, isolation of the biological signature in reflectance data obtained from aerial/orbital platforms has not been achieved, even when ground-based biological measurements have been available. This paper provides the cell-specific optical properties that are required to model the spectral signatures and broadband darkening of ice. Applying radiative transfer theory, these properties provide the physical basis needed to link biological and glaciological ground measurements with remotely sensed reflectance data. Using these new capabilities we confirm that biological impurities can influence ice albedo, then we identify 10 challenges to the measurement of bioalbedo in the field with the aim of improving future experimental designs to better quantify bioalbedo feedbacks. These challenges are (1) ambiguity in terminology, (2) characterising snow or ice optical properties, (3) characterising solar irradiance, (4) determining optical properties of cells, (5) measuring biomass, (6) characterising vertical distribution of cells, (7) characterising abiotic impurities, (8) surface anisotropy, (9) measuring indirect albedo feedbacks, and (10) measurement and instrument configurations. This paper aims to provide a broad audience of glaciologists and biologists with an overview of radiative transfer and albedo that could support future experimental design.