Early Concept for New Mission: A Spaceborne Multispectral Canopy Lidar

这个项目的目的是研制和设计一个新的卫星任务。这个新的任务概念将是一个星载多光谱冠层激光雷达（称为SpeCL，“斑点”），它可以测量森林的垂直轮廓，同时确定该轮廓的光谱特征。由于激光雷达可以提供关于森林结构的非常详细的三维信息，它们在减少陆地碳循环的不确定性和支持土地覆盖的精确测绘方面具有很大的潜力。特别小组任务的主要科学目标是利用适当的抽样策略确定世界森林地上生物量的全球分布，并减少与陆地生物圈有关的碳储量和通量计算中的不确定性。为什么这很重要？与林业有关的温室气体（毁林和退化）约占全球排放量的17%，超过整个全球运输网络。最近提交给总理的一份报告（2008年《Eliasch全球森林融资评论》）预测，如果不采取行动，到2100年，仅森林砍伐造成的气候变化的全球经济成本就可能达到每年1万亿美元。目前，土地利用变化产生的大部分碳排放来自热带地区，这是森林砍伐的结果，随着有机物燃烧或腐烂，森林砍伐将储存在生物质和土壤中的碳（以二氧化碳的形式）释放到大气中。因此，对土地覆盖变化的定期监测和评估对于了解自然变化和人为变化的程度和影响至关重要。此外，对全球碳循环的分析表明，碳的年排放量大于大气和海洋中碳的年累积量，这表明除了土地利用变化导致的碳汇外，还存在陆地碳汇。值得注意的是，在过去的几十年里，这一尚未解释的剩余碳汇在总碳排放中所占的比例似乎有所增加，这意味着碳反馈正在相互抵消。这种平衡不太可能持续下去。特别报告员任务是限制土地利用/土地利用变化产生的碳净排放和剩余陆地碳汇的一个机会。如果我们留给应对的时间太少，在理解碳预算方面的任何进一步拖延都可能产生严重的长期后果。我们该怎么做呢？爱丁堡率先开发了世界上第一台多光谱冠层激光雷达（专利号0808340.4）。利用CEOI的种子玉米基金，我们建立了第一个4波长激光雷达，在实验室中演示了它的使用，并模拟了季节响应。一种机载MSCL （A-MSCL）仪器已于7月1日设计并向NERC提出。在对未来任务机会的预期中（以及所需的较长准备时间），迫切需要确定星载MSCL的可行性和技术准备情况。首先，我们将创建一个高成本但低风险的传统小卫星配置的概念，其成本上限为1亿英镑。然后，我们的目标是将这一概念发展为超低成本（< 500万英镑），快速部署（3年内）的微型卫星平台，使用现成的组件和适当的“经过验证”的技术。为此，我们将考虑使用模块化CubeSat平台的高度新颖、高风险但成本非常低的选择。

Our Aim This project aims to develop and design a new satellite mission. This new mission concept will be a spaceborne multispectral canopy lidar (called SpeCL, 'speckle') that can measure the vertical profile of a forest and simultaneously determine the spectral characteristics of that profile. Since lidars can provide highly detailed 3D information on the structure of forest they have great potential in reducing the uncertainties in the terrestrial carbon cycle and of supporting the accurate mapping of land cover. The primary scientific objective of the SpeCL mission would be to determine the global distribution of above ground biomass in the world's forests using an appropriate sampling strategy, and to reduce uncertainties in the calculations of carbon stocks and fluxes associated with the terrestrial biosphere. Why is this important? Greenhouse gases associated with forestry (deforestation and degradation) accounts for roughly 17% of global emissions, more than the entire global transport network. A recent report to the Prime Minister (the 2008 Eliasch Review on Financing Global Forests) predicts that without action, the global economic cost of climate change caused by deforestation alone could reach $1 trillion a year by 2100. Most emissions of carbon from land-use change are currently from the tropics as a result of deforestation, which releases the carbon stored in biomass and soils to the atmosphere (as CO2) as organic matter is burned or decays. The regular monitoring and assessment of land cover change is therefore essential to understand the extent and impact of natural and anthropogenic changes Furthermore, analysis of the global carbon cycle shows that the annual emissions of carbon are larger than the annual accumulations of carbon in the atmosphere and oceans, suggesting a terrestrial sink for carbon in addition to that attributable to changes in land use. Remarkably, this as yet unexplained residual sink seems to have increased over the last decades in proportion to total carbon emissions, implying that carbon feedbacks are offsetting each other. This balance is unlikely to persist. The SpeCL mission is an opportunity to constrain both the net emissions of carbon from land-use/land-use change, and the residual terrestrial sink. Any further delay in understanding the carbon budget may have serious long term consequences if we leave too little time to respond. How will we do it? Edinburgh has pioneered the development of the world's first Multi Spectral Canopy Lidar (patent number 0808340.4). Using seedcorn funding from CEOI, we built the first 4-wavelength lidar, demonstrated its use in the lab and modelled the seasonal response. An airborne MSCL (A-MSCL) instrument has been designed and proposed to NERC on July 1st. In anticipation of future mission opportunities (and the long lead time required), there exists an imminent need for determining the feasibility and technical readiness of a spaceborne MSCL. In the first instance we will create a concept for the high cost, but low risk option of a traditional small satellite configuration with a cost ceiling of £100M. We will then aim to develop this concept to an ultra-low cost (<£5M), rapid deployment (within 3 years) micro-satellite platform using off-the-shelf components and where appropriate, 'proved' technologies. To this end we will consider the highly novel, high risk, but very low cost option of using a modular CubeSat platform.