The design of a space-borne multispectral canopy lidar to estimate global carbon stock and gross primary productivity
The design of a space-borne multispectral canopy lidar to estimate global carbon stock and gross primary productivity
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DOI：
10.1117/12.898166
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发表时间：
2011-09
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影响因子：
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通讯作者：
J. Jack;E. Rumi;D. Henry;I. Woodhouse;C. Nichol;M. Macdonald
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文献类型：
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作者：
J. Jack;E. Rumi;D. Henry;I. Woodhouse;C. Nichol;M. Macdonald
了解全球碳循环的动态是科学界面临的最具挑战性的问题之一。测量陆地碳汇规模以及监测短期和长期变化的能力对于环境决策至关重要。森林是陆地生物系统的重要组成部分，了解全球碳循环，地上生物量（AGB）和总初级生产力（GPP）是关键参数。目前对AGB和GPP的估计不足以支持全球碳循环模型，更准确的估计将改善对未来的预测和对这些汇可能行为的估计。已经提出了各种植被指数来描述森林的特征，包括树冠高度、树冠面积、归一化植被指数（NDVI）和光化学反射指数（PRI）。NDVI和PRI都是通过测量特定波长的反射率获得的，并通过被动测量进行估算。使用多光谱激光雷达测量归一化植被指数和优先指数及其在森林内的垂直分布，是对现有技术的重大改进。本文介绍了一种先进的多光谱冠层激光雷达的设计方法，使用四个波长同时测量冠层的垂直轮廓。建议将该仪器放置在太阳同步极轨道上绕地球运行的卫星上，以便在矩形网格上以大约1公里的间隔提供样本，并有适当的重访频率。将介绍系统工程概念设计。
Understanding the dynamics of the global carbon cycle is one of the most challenging issues for the scientific community. The ability to measure the magnitude of terrestrial carbon sinks as well as monitoring the short and long term changes is vital for environmental decision making. Forests form a significant part of the terrestrial biosystem and understanding the global carbon cycle, Above Ground Biomass (AGB) and Gross Primary Productivity (GPP) are critical parameters. Current estimates of AGB and GPP are not adequate to support models of the global carbon cycle and more accurate estimates would improve predictions of the future and estimates of the likely behaviour of these sinks. Various vegetation indices have been proposed for the characterisation of forests including canopy height, canopy area, Normalised Difference Vegetation Index (NDVI) and Photochemical Reflectance Index (PRI). Both NDVI and PRI are obtained from a measure of reflectivity at specific wavelengths and have been estimated from passive measurements. The use of multi-spectral LiDAR to measure NDVI and PRI and their vertical distribution within the forest represents a significant improvement over current techniques. This paper describes an approach to the design of an advanced Multi- Spectral Canopy LiDAR, using four wavelengths for measuring the vertical profile of the canopy simultaneously. It is proposed that the instrument be placed on a satellite orbiting the Earth on a sun synchronous polar orbit to provide samples on a rectangular grid at an approximate separation of 1km with a suitable revisit frequency. The systems engineering concept design will be presented.