UK/Brazil Research Network for an Amazonian Carbon Observatory

温室气体CO2和CH4对气候的重要性是公认的。广泛的科学共识是，人类活动是这些温室气体（ghg）浓度增加的主要驱动因素，尤其是在过去的一个世纪里。根据精确的地表测量，我们知道人类活动排放的二氧化碳约有45%留在大气中。净平衡显然被全球海洋、陆地植被和土壤所吸收。然而，这些碳循环的自然组成部分的性质、位置和强度存在很大的不确定性。亚马逊地区是世界上最大的森林地区之一，代表着最大的地上有机碳储存库。亚马逊不仅受到气候变化的影响，而且由于人口的快速增长和经济的快速发展，导致了广泛的森林砍伐和城市化，亚马逊也受到了快速的环境变化的影响。这些外部驱动因素可能导致碳平衡的进一步变化，导致储存在生物质和土壤中的碳释放到大气中，从而加速大气温室气体浓度的增长和气候变化。尽管它在全球碳循环中发挥着重要作用，但目前对亚马逊雨林以及更广泛的热带地区的碳循环的了解很少受到观测的限制。在气候变暖的情况下，这些知识差距导致亚马逊地区碳收支的命运存在很大的不确定性，从而阻碍了碳气候模型的任何预测技能。自2009年以来，亚马逊地区一直是英国和巴西主要研究项目的重点，这些项目旨在通过在一些地点对二氧化碳和甲烷进行详细但局部的飞机观测，提高我们对亚马逊地区碳循环的认识。这些测量是一个巨大的进步，但它们在空间和时间上仍然高度局限。通过在地面网络采样不足的地区提供密集的时空覆盖观测，星载测量有能力填补这些观测空白。然而，这种天基观测必须适当地与世界气象组织（WMO）参考标准挂钩，以确保碳循环界接受天基数据集，并防止在区域碳预算方面产生误导性结果。该建议的中心目标是将现场测量与遥感卫星数据联系起来，建立一个综合的亚马逊碳观测站，其中卫星数据通过填补现场站点之间的空白和扩大整个亚马逊地区的覆盖范围来补充现场数据。现在可以通过日本GOSAT卫星上的专用仪器对温室气体进行卫星观测，结果看起来很有希望。然而，亚马逊河流域（和热带地区）上空的卫星检索本身就很困难，而且这种温室气体检索的准确性尚未确定，这是利用天基数据限制亚马逊河流域上空碳通量的一个主要障碍。我们建议建立一个由巴西和英国研究人员组成的网络，以弥合现场观测和遥感观测与社区之间的差距，并评估遥感温室气体浓度的可行性，以便监测亚马逊地区的温室气体通量，从而提高我们对亚马逊地区碳循环的了解，并提高我们观测热带碳通量的能力。拟议中的网络将汇集世界一流的专业知识，以解决高度相关和及时的科学问题，这些问题将促进我们对亚马逊碳循环的理解。它将有力地加强和扩大英国和巴西的关系，它将有助于进一步加强英国研究人员在与该提案相关的许多领域的领导作用。

The importance of the greenhouse gases CO2 and CH4 for climate is well established. There is broad scientific consensus that human activities are the main driver for increasing concentrations of these greenhouse gases (GHGs), particularly over the past century. Based on accurate surface measurements we know that approximately 45% of the CO2 emitted by human activities remain in the atmosphere. The net balance is apparently being taken up by global oceans, terrestrial vegetation and soils. However, there are substantial uncertainties associated with the nature, location and strength of these natural components of the carbon cycle. The Amazon region is one of the largest forested regions in the world, representing the largest reservoir of above ground organic carbon. Amazonia is not only subject to changes in climate but also to rapid environmental change due to fast population growth and economic development causing extensive deforestation and urbanisation. Such external drivers can lead to further shifts in the carbon balance resulting in release of carbon stored in the biomass and soil to the atmosphere, with implications for accelerating the growth of atmospheric GHG concentrations and climate change. Despite its important role for the global carbon cycle, current understanding of the Amazonian, and more broadly the tropical, carbon cycle is poorly constrained by observations. These knowledge gaps result in large uncertainties in the fate of the Amazonian carbon budget under a warming climate, and consequently hamper any predictive skill of carbon-climate models. Since 2009, the Amazon region has been the focus of major UK and Brazilian research projects that aim at improving our knowledge of the Amazonian carbon cycle using detailed, but localized aircraft observations of CO2 and CH4 at a number of sites. These measurements are a great advance but they remain highly localized in space and time. Space-borne measurements have the ability to fill these observational gaps by providing observations with dense spatial and temporal coverage in regions poorly sampled by surface networks. It is essential, however, that such space-based observations are properly tied to the World Meteorological Organization (WMO) reference standard to ensure acceptance of space-based datasets by the carbon cycle community and to prevent misleading results on regional carbon budgets. The central aim of this proposal is to link the in-situ measurements with remotely sensed satellite data to establish an integrated Amazonian Carbon Observatory where satellite data complements the in situ data by filling the gaps between the in situ sites and by extending the coverage over the whole Amazon region.Satellite observations of GHGs are now available from a dedicated instrument on board the Japanese GOSAT satellite and results look very promising. However, satellite retrievals over the Amazon (and the Tropics) are intrinsically difficult and the accuracy of such GHG retrievals has not been established for this region which is a major obstacle for the exploitation of space-based data to constrain carbon fluxes over the Amazon. We propose to establish a network of Brazilian and UK researchers to bridge the gap between in-situ and remote sensing observations and communities and to evaluate the feasibility of remote sensing of GHG concentrations for the purpose of GHG flux monitoring over Amazonia to improve our understanding of the Amazonian carbon cycle and to increase our ability for observing tropical carbon fluxes.The proposed network will bring together world-class expertise to address highly relevant and timely scientific questions that will advance our understanding of the carbon cycle of the Amazon. It will strongly strengthen and expand UK and Brazilian relationships and it will help further strengthen the leading role of UK researchers in many areas relevant to this proposal.