Data-driven modelling of shortwave radiation transfer to snow through boreal birch and conifer canopies RADIATION TRANSFER TO SNOW THROUGH BOREAL BIRCH AND CONIFER CANOPIES
Data-driven modelling of shortwave radiation transfer to snow through boreal birch and conifer canopies RADIATION TRANSFER TO SNOW THROUGH BOREAL BIRCH AND CONIFER CANOPIES
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短波辐射通过北方桦树和针叶树冠层传输到雪的数据驱动建模 通过北方桦树和针叶树冠层到雪的辐射传输
DOI：
10.1002/hyp.9849
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发表时间：
2013
影响因子：
3.2
通讯作者：
Reid T
中科院分区：
文献类型：
--
作者：
Reid T
水文和地表模型需要简单但准确的方法来预测通过植被传输到雪的太阳辐射，并通过与数据的直接比较来支持。2011年春季，在瑞典Abisko附近的稀疏桦树林和芬兰Sodankylä附近的针叶混交林中，在不同林冠结构和密度的森林地块中部署了20个短波日射强度计。还测量了冠层上方的全球和漫射短波辐照度。这些数据被用来测试一个模型，使用半球形的照片，明确估计散射辐射和直接光束传输，以及两个模型，适用于散装冠层参数和版本的比尔定律。所有这三个模型预测冠层短波传输同样无叶白桦林，但针叶树，散装方法表现不佳。此外，一个现有的模型之间的多重反射冠层和雪被认为是适合桦树，但不针叶树。一种新的基于半球平均天空视图分数的经验关系的批量方法显示了两个站点的性能改善;这表明避免使用光学方法计算的植物面积指数的好处，这可能会引入误差。此外，使用常见的经验扩散辐射模型的测试结果显示，低估了短波传输高达7%，相对于使用的数据，这表明新的扩散模型需要高纬度地区。版权所有© 2013约翰威利父子有限公司.
Hydrological and land surface models require simple but accurate methods to predict the solar radiation transmitted through vegetation to snow, backed up by direct comparisons to data. Twenty shortwave pyranometers were deployed in forest plots of varying canopy structures and densities in sparse birch forest near Abisko, Sweden, in spring 2011 and mixed conifer forest near Sodankylä, Finland, in spring 2012. Above‐canopy global and diffuse shortwave irradiances were also measured. These data were used to test a model that uses hemispherical photographs to explicitly estimate both diffuse radiation and direct beam transmission, as well as two models that apply bulk canopy parameters and versions of Beers Law. All three models predict canopy shortwave transmission similarly well for leafless birch forest, but for conifers, the bulk methods perform poorly. In addition, an existing model of multiple reflections between canopy and snow was found to be suitable for birch, but not conifers. A new bulk approach based on empirical relationships with hemisphere‐averaged sky view fraction showed improved performance for both sites; this suggests benefits of avoiding the use of plant area index calculated from optical methods, which can introduce errors. Furthermore, tests using common empirical diffuse radiation models were shown to underestimate shortwave transmission by up to 7% relative to using the data, suggesting that new diffuse models are required for high latitudes. Copyright © 2013 John Wiley & Sons, Ltd.