SGER: Modeling River Nitrogen Export to Coastal Zones in the Community Climate System Model (CCSM)

增加向沿海地区输送的氮是人类干扰氮循环的主要后果之一，并对沿海生产力和痕量气体排放产生重要影响。受此观察的启发，这项研究是在社区气候系统模式(CCSM)中模拟河流营养物质输送的首次尝试。DAYCENT模型的淋溶N通量是最终将在CCSM陆地模型(CLM)中发展的土壤农业生物地球化学模型的基础，它将与CLM河流迁移模型(RTM)相耦合。(DAYCENT是世纪模型的每日时间步长版本，世纪模型是模拟每日微量气体通量和土壤水动力学的土壤有机质模型)。模拟的河流N通量将与观测数据库和根据统计相关性得出的N出口的简单经验估计进行比较。通过与模拟和测量的大气N输入以及估计的沿海自然硝化速率进行比较，将使用对沿海地区的模拟N出口通量来评估沿海N预算。拟议研究的更广泛影响包括制定了一个框架，用于模拟CCSM中的河流溶质输送，这将有助于在CCSM中更完整地表示全球N循环，并将为CLM与区域沿海模式的耦合提供重要的边界条件。

Increased nitrogen (N) delivery to coastal areas is one of the major consequences of human perturbation to the nitrogen cycle, and has important impacts on coastal productivity and trace gas emissions. Motivated by this observation, this research is a first effort to model river nutrient transport in the Community Climate System Model (CCSM). Leached N fluxes from the DAYCENT model, which serves as the basis for the soil agricultural biogeochemistry model that eventually will be developed within the CCSM Land Model (CLM), will be coupled to the CLM River Transport Model (RTM). (DAYCENT is the daily time step version of the Century Model, a soil organic matter model that simulates daily trace gas fluxes and soil water dynamics). Modeled river N fluxes will be compared to observational databases and to simple empirical estimates of N export derived from statistical correlations. Modeled N export fluxes to coastal areas will be used to evaluate coastal N budgets, through comparison to modeled and measured atmospheric N inputs and to estimated natural coastal nitrification rates. The broader impacts of the proposed study include the development of a framework for the simulation of river solute transport in the CCSM, which will contribute to the more complete representation of the global N cycle in the CCSM and will provide important boundary conditions for the coupling of the CLM with regional coastal models.