Assessing Ecosystem Carbon Dynamics over North America by Integrating Eddy Covariance, MODIS, and New Ecological Data through Upscaling and Model-Data Synthesis

准确描述区域到全球尺度的碳收支将提高我们对土地和气候之间反馈的理解，并将对气候领域的政策制定提供实质性帮助。虽然人们普遍认为北美是一个巨大的碳汇，但这个碳汇的规模和分布并不为人所知，其空间和时间的变化存在很大的不确定性。最近利用快速和准确的技术对当地碳通量进行的测量、新的计算机模型和技术的开发以及卫星信息检索和分析的改进创造了新的机会。该项目将以多种方式利用这些进步。该项目将整合在塔顶进行的连续当地碳通量观测、卫星和飞机遥感数据以及关于该国重要生态系统的新数据（如植物质量和氮含量）。将使用先进的方法将地面和遥感信息合并成考虑其空间分布和时间动态的模型。还将对数据和模型进行有关不确定性的分析。研究结果将包括对陆地碳汇和碳源的估计，并确定每年对其产生影响的因素，特别关注极端条件，如严重干旱、野火或木材采伐。这项工作将为北美生态系统中碳的数量和动态提供一个新的基准。其结果将用于国家气候变化评估，特别是因为一般预测未来极端气候事件和其他干扰将更加严重和频繁。该项目还将开发更普遍有用的方法，这些方法可由环境观测网络加以调整，并用于对未来状况进行预测和评估。将通过项目科学家参加会议和出版物向其他科学家公布项目数据和结果。这项工作还将促进以高中教育和教师培训为目标的若干教育活动。

Accurate descriptions of the carbon budget at regional to global scales would improve our understanding of feedbacks between the land and climate and would be of substantial assistance in policy making in the climate area. Although there is general agreement that North America is a large sink for carbon, the size and distribution of this sink are not well known and there are large uncertainties in its variation in space and time. Recent measurements of local carbon fluxes using fast and accurate technology, development of new computer models and techniques, and improvements in the retrieval and analysis of satellite information, have created new opportunities. This project will capitalize on these advances in several ways. The project will integrate continuous local carbon flux observations made at the tops of towers, satellite and aircraft remote sensing data, and new data on important ecosystems of the country (such as the amount of plant mass and nitrogen content). Advanced methods will be used to merge the ground and remote information into models that consider its distribution in space and dynamics in time. Analysis of the uncertainties involved will also be conducted of the data and the models. The results will include estimates of carbon sinks and sources on land and identification of what affects them from year to year, with particular focus on extreme conditions, such as severe droughts, wildfires, or timber harvesting. This work will provide a new benchmark for the amount and dynamics of carbon in North American ecosystems. The results will be of use in national climate change assessments, especially because extreme climate events and other disturbances are generally projected to be more severe and frequent in the future. The project will also develop methods that are more generally useful and that could be adapted by environmental observation networks and used for making and evaluating predictions of future conditions. Release of project data and results to other scientists will be done through participation of the project scientists in meetings and publications. The work will also contribute to several education activities aimed at high school education and teacher training.