Collaborative Research: The carbon balance of Lake Superior: Modeling lake processes and understanding impacts on the regional carbon budget

北美碳计划（NACP）旨在(1)发展定量的科学知识、可靠的观测和模型，以确定北美和邻近海洋盆地的CO2、CH4和CO的排放和吸收、碳储量的变化以及调节这些过程的因素；(2)为区域和大陆尺度的全碳核算提供科学依据。劳伦森五大湖覆盖了美国八大湖区25%的土地面积，其二氧化碳排放量和季节循环可与当地陆地生态系统相媲美。虽然它们对区域碳平衡的贡献可能很大，但目前对这些通量的了解甚少。来自苏必利尔湖的二氧化碳通量特别令人感兴趣，因为它们可能直接影响附近AmeriFlux塔的观测，但由于目前缺乏量化，苏必利尔湖的通量目前在分析这些数据时被忽略了。由于需要提高对大湖二氧化碳通量的了解，该项目将把生态系统碳模块与苏必利尔湖现有的水动力模型结合起来。该模式将导致对空气-水CO2通量及其时空变异性的估计。还将获得新的观测结果，以提高对冬季碳循环的认识，并对模型进行约束。利用模式输出，将评估苏必利尔湖二氧化碳通量对AmeriFlux塔观测值和区域碳收支的影响。五个关键的研究问题是：1。苏必利尔湖空气-水碳通量的大小是多少？通量如何受到物理气候变化的影响？苏必利尔湖的碳循环在冬季表现如何？苏必利尔湖碳收支中最重要的不确定因素是什么？苏必利尔湖碳通量如何影响区域碳收支？该项目汇集了一个跨学科团队，以提高对“全球水和碳循环之间和内部的复杂关系”的理解。通过联合考虑沿海碳处理和陆地碳预算，该项目解决了海洋和地球科学部门的研究重点。更广泛的影响该项目将解决有关中西部上游碳预算的基本问题，提高对沿海碳循环的认识，并为未来五大湖的研究产生一套研究重点。两名学生和一名博士后将使用数据和模型学习苏必利尔湖的碳循环，该项目将增加五大湖碳科学的区域合作。来自代表性不足群体的本科生将通过MTU的REU计划积极参与该项目。该小组还将努力向公众传播他们的发现。

The North American Carbon Program (NACP) intends (1) to develop quantitative scientific knowledge, robust observations, and models to determine emissions and uptake of CO2, CH4 and CO, changes in carbon stocks, and factors regulating these processes for North America and adjacent ocean basins; and (2) to develop the scientific basis for full carbon accounting on regional and continental scales. The Laurentian GreatLakes cover 25% of the land area of the 8 Great Lakes states, and CO2 emission and seasonal cycling from them may be comparable to local terrestrial ecosystems. Though their contributions to the regional carbon balance may be significant, these fluxes are currently poorly understood. CO2 fluxes from Lake Superior are of particular interest because they may directly impact observations at nearby AmeriFlux towers, yet due to the current lack of quantification, Lake Superior fluxes are presently neglected in analysis of these data.Motivated by the need for improved knowledge of Great Lake CO2 fluxes, this project will couple an ecosystem-carbon module with an existing hydrodynamic model of Lake Superior. This model will lead to estimates of the air-water CO2 fluxes and their spatial and temporal variability. New observations to improve knowledge of carbon cycling in winter and to constrain the model will also be obtained. With model output, the impact of Lake Superior CO2 fluxes on observations at AmeriFlux towers and on the regional carbon budget will be evaluated. The five key research questions are:1. What is the magnitude of the air-water carbon flux in Lake Superior?2. How are the fluxes influenced by variability in the physical climate?3. How does Lake Superior's carbon cycle behave in winter?4. What are the most important uncertainties in the Lake Superior carbon budget?5. How do Lake Superior carbon fluxes impact the regional carbon budget?This project brings together an interdisciplinary team to improve understanding of the "complex relationships between and within the global water and carbon cycles". By jointly considering coastal carbon processing and terrestrial carbon budgets, this project addresses research priorities of both the Ocean and Earth Sciences divisions.Broader ImpactsThis project will address fundamental questions about the upper Midwest carbon budget, improve knowledge of coastal carbon cycling, and generate a set of research priorities for future study of Great Lakes. Two students and one postdoc will learn about Lake Superior carbon cycling using data and models, and the project will increase regional collaborations for Great Lakes carbon science. Undergraduates from under-represented groups will actively participate in the project through MTU's REU program. The team will also work to communicate their findings to the general public.