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

氮向海岸带的输送增加是人类活动对氮循环的影响之一，对海岸带生产力和痕量气体排放有重要影响。 受此观察的启发，本研究是第一次尝试在社区气候系统模式（CCSM）中模拟河流营养盐输运。 从DAYCENT模型，作为土壤农业生态地球化学模型，最终将在CCSM土地模型（CLM）的基础上开发的淋溶N通量，将耦合到CLM河流运输模型（RTM）。 （DAYCENT是世纪模型的每日时间步长版本，这是一个模拟每日微量气体通量和土壤水分动态的土壤有机质模型）。 模拟河流氮通量将比较观测数据库和简单的经验估计来自统计相关性的N出口。 模拟氮输出通量沿海地区将被用来评估沿海氮预算，通过比较模拟和测量的大气氮输入和估计的自然沿海硝化率。 更广泛的影响，拟议的研究包括开发一个框架，用于模拟河流溶质运移的CCSM，这将有助于更完整的代表性的全球N循环的CCSM，并将提供重要的边界条件耦合的CLM与区域沿海模型。

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.