Collaborative Research: ETBC--The Cycling of Nitrogen in an Earth System Model: Constraints and Implications for Climate Change

合作研究：ETBC——地球系统模型中的氮循环：气候变化的约束和影响

• 批准号: 1021613
• 负责人: Peter Hess
• 金额: $ 68.72万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-10-01 至 2016-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1021613&HistoricalAwards=false
• 关键词: Collaborative; Research; ETBC; Cycling; Nitrogen

The overarching goals of this project are: 1) to constrain the global budget of reactive nitrogen (Nr) through a combination of numerical simulations, data synthesis and analysis; and 2) to produce initial estimates of the overall interaction between reactive nitrogen cycling and climate. The nitrogen cycle is a key regulator of the Earth's climate system, linking terrestrial, marine, photochemical, and industrial processes, and modulating the carbon cycle. Over the last century and a half, expansion and intensification of agriculture and fossil fuel combustion have led to a more than doubling of Nr emissions to the atmosphere with profound impacts on the earth system. A closed global Nr cycle will be simulated within the CCSM (Community Climate System Model) by tracking Nr across three model domains: (1) atmosphere, (2) land, including native and agroecosystems, and (3) fresh and oceanic waters. While the basis for much of this work has already been developed within the CCSM, the nitrogen cycle has not been coupled across the different model domains. In the fully coupled system, each model domain will simulate the transport and production of Nr within its domain and the chemistry and loss of Nr from its domain, with the requirement that the nitrogen fluxes between the domains be self-consistent. This mass-balanced approach will avoid the untracked losses of Nr that occur when the nitrogen cycle is modeled in isolation within a single domain. Moreover, it will consider the diverse and opposing impacts of Nr on terrestrial carbon sinks and on the radiatively important species nitrous oxide, ozone, methane and aerosol ammonium sulfate. It is hypothesized that the overall effect of a changing Nr cycle on these four atmospheric species will lead to a warming sufficient to offset the cooling associated with increased Nr availability and increased terrestrial carbon uptake.The synthesized datasets for evaluating the nitrogen cycle in Earth System Models, the coupled nitrogen-carbon-climate model developed here, and the simulations with the CCSM will be made broadly available to university and national laboratory communities and will contribute to the upcoming IPCC 5th Assessment. Most of the principal investigators in this project are actively engaged in graduate student education and training, and most participate in undergraduate activities as well. The research will support four additional graduate students and one postdoctoral associate as well as a number of undergraduates. All will become involved in the research activities both at their respective local institutions, as well as across all institutions and disciplines involved in the project.

该项目的总体目标是：1）通过数值模拟、数据综合和分析相结合来限制活性氮（Nr）的全球预算； 2) 对活性氮循环与气候之间总体相互作用进行初步估计。氮循环是地球气候系统的关键调节器，连接陆地、海洋、光化学和工业过程，并调节碳循环。在过去的一个半世纪中，农业和化石燃料燃烧的扩张和集约化导致大气中的铌排放量增加了一倍多，对地球系统产生了深远的影响。通过跟踪三个模型域的 Nr，将在 CCSM（社区气候系统模型）内模拟封闭的全球 Nr 循环：(1) 大气，(2) 土地，包括本地和农业生态系统，以及 (3) 淡水和海洋水域。虽然大部分工作的基础已经在 CCSM 内开发出来，但氮循环尚未在不同的模型域之间耦合。在完全耦合系统中，每个模型域将模拟其域内 Nr 的传输和产生以及 Nr 从其域中的化学反应和损失，并要求域之间的氮通量自洽。这种质量平衡方法将避免在单个域内单独模拟氮循环时发生的未追踪的 Nr 损失。此外，还将考虑Nr对陆地碳汇和辐射重要物种一氧化二氮、臭氧、甲烷和气溶胶硫酸铵的多种和相反的影响。据推测，氮循环变化对这四种大气物种的总体影响将导致变暖，足以抵消与氮可用性增加和陆地碳吸收增加相关的降温。用于评估地球系统模型中氮循环的综合数据集，这里开发的氮-碳-气候耦合模型以及 CCSM 的模拟将广泛提供给大学和国家实验室社区，并将为即将到来的 IPCC 第五次评估做出贡献。该项目的大多数主要研究者积极从事研究生教育和培训，并且大多数也参与本科生活动。该研究将支持另外四名研究生和一名博士后以及一些本科生。所有人都将参与各自当地机构以及参与该项目的所有机构和学科的研究活动。