N2O from the Swiss midlands: regional sources and hot spots

该项目将首次在位于瑞士高原农村环境中的一座高塔（Beromünster）进行实地和区域规模的N2 O浓度和特定地点同位素组成的实时准连续测量。在一个自上而下的方法，使用这些测量，后向拉格朗日粒子扩散模型（FLEXPART-COSMO）和反演系统，总N2 O的源强度和它的同位素签名在北方瑞士将被确定。在一个互补的自下而上的方法，最先进的地球化学模型（LandscapeDNDC）将扩展一个子模块能够模拟从土壤中排放的N2 O的同位素签名。模型扩展将基于生态系统氮循环相关过程的富集因子。景观DNDC是最适合这种方法，因为除了所有其他相关的生态系统N循环过程，也微生物过程，如硝化和反硝化已经实施。该模型将补充算法，反映特定的同位素生产和排放的N2 O的网站偏好的过程。扩展的LandscapDNDC模型结合土壤、植被和管理方面的详细地理空间信息，最终将用于确定和评估土壤N2 O排放的地点、田间和区域尺度模式。后向拉格朗日输运模拟将提供这些自下而上的估计和在高塔的测量之间的必要联系，并将允许检查地球化学模型预测和观测之间的一致性，并确定我们目前对潜在过程的理解中的弱点。这项工作计划进行为期三年的研究，基于博士（WP 1）和两年（50%）的研究后，在Empa博士职位（WP 3）由空气污染与环境技术实验室的专家提供咨询，在KIT（WP 2）为期三年的博士职位由气象和气候研究所IMK-IFU，加米施-帕尔滕基兴的专家指导。

This project will, for the first time, conduct real-time quasi-continuous measurements of N2O concentrations and site-specific isotopic composition at field and regional scale at a tall tower (Beromünster), located in a rural environment on the Swiss plateau. In a top-down approach, using these measurements, backward Lagrangian particle dispersion modeling (FLEXPART-COSMO) and an inversion system, the source strengths of total N2O and its isotopic signatures in northern Switzerland will be determined. In a complementary bottom-up approach, a state of the art biogeochemical model (LandscapeDNDC) will be extended with a sub-module capable for simulating isotopic signatures of N2O emitted from soils. The model extension will be based on enrichment factors for the relevant processes involved in ecosystem nitrogen cycling. LandscapeDNDC is the most suitable for this approach since besides all other relevant ecosystem N cycling processes also microbial processes such as nitrification and denitrification are already implemented. The model will be supplemented with algorithms reflecting process specific isotopic site preferences of produced and emitted N2O. The extended LandscapDNDC model in combination with detailed geospatial information on soil, vegetation and management will finally be used to identify and assess site, field and regional-scale patterns of soil N2O emissions. The backward Lagrangian transport simulations will provide the necessary link between these bottom-up estimates and the measurements at the tall tower and will allow to check for consistency between biogeochemistry model predictions and observations and to identify weaknesses in our current understanding of the underlying processes.The work is planned for a three-year study based on a PhD (WP 1) and a two year (50 %) post-doc position at Empa (WP 3) advised by the experts of the Laboratory for Air Pollution & Environmental Technology and a three-year PhD position at KIT (WP 2) guided by the specialists at the Institute of Meteorology and Climate Research IMK-IFU, Garmisch-Partenkirchen.