Global mapping of foliage clumping index using multi-angular satellite data
Global mapping of foliage clumping index using multi-angular satellite data
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DOI：
10.1016/j.rse.2005.05.003
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发表时间：
2005-09-15
影响因子：
13.5
通讯作者：
Leblanc, SG
中科院分区：
文献类型：
--
作者：
Chen, JM;Menges, CH;Leblanc, SG
首次尝试使用多角度POLDER I数据，根据已证明适用于加拿大大陆的方法绘制植被丛生指数的全球地图。丛生指数量化了不同的冠层结构，如树冠，灌木和行播作物，相对于随机分布的树叶分组的水平。植物叶片丛生显著改变了其辐射环境，从而影响植被生长以及水和碳循环。丛生指数在生态和气象模型中是有用的，因为它提供了新的结构信息，除了从单角度遥感检索的有效叶面积指数，并允许在树冠中的阳光照射和阴影叶的准确分离。使用名为“4尺度”的几何光学模型探索角指数（热点和暗点之间的归一化差异）和聚集指数之间的关系。开发了4-Scale中使用的机制热点模型的简化版本，以从多角度测量中获得热点反射率用于映射目的。虽然还需要进一步研究以减少地形影响，但已绘制出树木（灌木）覆盖率高的地区的准确聚类图。(C)2005年爱思唯尔公司All rights reserved.
Global mapping of the vegetation clumping index is attempted for the first time using multi-angular POLDER I data based on a methodology that has been demonstrated to be applicable to Canada's landmass. The clumping index quantified the level of foliage grouping within distinct canopy structures, such as tree crowns, shrubs, and row crops, relative to a random distribution. Vegetation foliage clumping significantly alters its radiation environment and therefore affects vegetation growth as well as water and carbon cycles. The clumping index is useful in ecological and meteorological models because it provides new structural information in addition to the effective LAI retrieved from mono-angle remote sensing and allows accurate separation of sunlit and shaded leaves in the canopy. The relationship between an angular index (normalized difference between hotspot and darkspot) and the clumping index is explored using a geometrical optical model named "4-Scale". A simplified version of the mechanistic hotspot model used in 4-Scale is developed to derive the hotspot reflectance from multi-angle measurements for mapping purposes. An accurate clumping map for areas with significant tree (shrub) covers has been achieved, although further research is required to reduce topographic effects. (C) 2005 Elsevier Inc. All rights reserved.