The BIOMASS mission: Mapping global forest biomass to better understand the terrestrial carbon cycle
The BIOMASS mission: Mapping global forest biomass to better understand the terrestrial carbon cycle
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DOI：
10.1016/j.rse.2011.03.020
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发表时间：
2011-11-15
影响因子：
13.5
通讯作者：
Ulander, L.
中科院分区：
文献类型：
--
作者：
Le Toan, T.;Quegan, S.;Ulander, L.
鉴于迫切需要改进全球生物量测绘，而且目前缺乏任何能够满足这一需要的空间系统，建议欧洲航天局进行第三周期地球探测器核心飞行任务的生物量飞行任务，并于2009年3月选定进行可行性研究(A阶段)。访问团的目标是：1)量化全球森林生物量的大小和分布，以改进资源评估、碳核算和碳模型；2)每年或更好地监测和量化全球陆地森林生物量的变化，从而改进对陆地碳源(主要来自毁林)的估计；和陆地碳汇，用于森林再生和植树造林。这些科学目标要求飞行任务测量北纬70度至56度的地面森林生物量，空间尺度为100-200米，误差不超过+/-20%或+/-10吨公顷(-1)，测量森林高度误差为+/-4米。为满足测量要求，飞行任务将携带一台具有干涉能力的P波段极化合成孔径雷达(中心频率435兆赫，带宽6兆赫)，在具有恒定入射角(在25度-35度范围内)的黎明-黄昏轨道上运行，重复周期为25-45天。在其5年的生命周期内，该飞行任务将能够提供根据强度数据得出的生物量的直接测量，以及由偏振干涉测量得出的森林高度的测量。生物量飞行任务的设计将两个主要观测线索结合在一起：(1)热带、温带和北部森林的长期空中观测，证明了P波段合成孔径雷达测量森林生物量的能力；(2)从Pol-InSAR恢复森林结构包括森林高度方面的新发展，以及关键的是，P波段对时间去相关的抵抗，这使得这一频率唯一适合于使用单一重复通过卫星进行生物量测量。这两种互补的测量方法被结合在单一的生物量传感器中，具有增加生物量降低前者的灵敏度而提高后者的灵敏度的令人满意的特性。本文综述了过去十年来从广泛的机载实验中建立的证据，这些证据表明了这种传感器提供所需测量的能力。目前，生物量P波段雷达似乎是唯一能够提供关于世界森林生物量及其变化的必要全球知识的传感器。此外，这一首次利用长波卫星合成孔径雷达探测地球环境的机会预计将产生一系列地球科学领域的新信息，包括干旱地区和极地冰层的地下结构以及森林淹没动态。(C)2011 Elsevier Inc.保留所有权利。
In response to the urgent need for improved mapping of global biomass and the lack of any current space systems capable of addressing this need, the BIOMASS mission was proposed to the European Space Agency for the third cycle of Earth Explorer Core missions and was selected for Feasibility Study (Phase A) in March 2009. The objectives of the mission are 1) to quantify the magnitude and distribution of forest biomass globally to improve resource assessment, carbon accounting and carbon models, and 2) to monitor and quantify changes in terrestrial forest biomass globally, on an annual basis or better, leading to improved estimates of terrestrial carbon sources (primarily from deforestation); and terrestrial carbon sinks due to forest regrowth and afforestation. These science objectives require the mission to measure above-ground forest biomass from 70 degrees N to 56 degrees Sat spatial scale of 100-200 m, with error not exceeding +/- 20% or +/- 10 t ha(-1) and forest height with error of +/- 4 m. To meet the measurement requirements, the mission will carry a P-Band polarimetric SAR (centre frequency 435 MHz with 6 MHz bandwidth) with interferometric capability, operating in a dawn-dusk orbit with a constant incidence angle (in the range of 25 degrees-35 degrees) and a 25-45 day repeat cycle. During its 5-year lifetime, the mission will be capable of providing both direct measurements of biomass derived from intensity data and measurements of forest height derived from polarimetric interferometry. The design of the BIOMASS mission spins together two main observational strands: (1) the long heritage of airborne observations in tropical, temperate and boreal forest that have demonstrated the capabilities of P-band SAR for measuring forest biomass; (2) new developments in recovery of forest structure including forest height from Pol-InSAR, and, crucially, the resistance of P-band to temporal decorrelation, which makes this frequency uniquely suitable for biomass measurements with a single repeat-pass satellite. These two complementary measurement approaches are combined in the single BIOMASS sensor, and have the satisfying property that increasing biomass reduces the sensitivity of the former approach while increasing the sensitivity of the latter. This paper surveys the body of evidence built up over the last decade, from a wide range of airborne experiments, which illustrates the ability of such a sensor to provide the required measurements.At present, the BIOMASS P-band radar appears to be the only sensor capable of providing the necessary global knowledge about the world's forest biomass and its changes. In addition, this first chance to explore the Earth's environment with a long wavelength satellite SAR is expected to make yield new information in a range of geoscience areas, including subsurface structure in arid lands and polar ice, and forest inundation dynamics. (C) 2011 Elsevier Inc. All rights reserved.