Canopy cycling of carbon dioxide, water vapour and reactive trace gases: Measurement of fluxes and plan exological modelling

植被冠层吸收由植物和/或土壤生物排放的微量气体的能力，最近已成为大气痕量气体收支的一个重要方面。(A)植被和土壤的生理和(或)表面特性，(B)湍流输送与痕量气体交换过程的相互作用，以及(C)湍流输送与大气化学变化的相互作用，控制着痕量气体的吸收/逸出量。在这方面，更好地理解冠层内的去耦合以及植被和大气边界层之间的耦合是至关重要的。氢氧化物的净垂直输送与一氧化碳或活性痕量气体(一氧化氮、氮氧化物、氧化氮、氢氧化氮、氢氧化氮)的垂直净输送之间存在着明显的差异。因此，该分项目的目的是测量和模拟水通量和双向示踪气体交换，以及所涉过程的相互耦合；长期和运动方面的实地测量得到实验室研究的补充。土壤中生物来源的NO排放将通过实验室实验来确定。在S的密集观测期间，进出土壤的通量将通过测量土壤空气剖面和土壤小室来量化。为了研究冠层内的储存、冠层循环和整个生态系统中非反应性和反应性痕量气体的交换，将测量浓度的垂直剖面以及冠层内和冠层以上的反应性痕量气体的通量(用涡旋协方差和改进的鲍文比技术)。在该模型中，冠层结构用单个植物的三维(非均匀)分布来表示，从而得到了详细的(m尺度)冠层内和冠层下标量和通量的概率密度函数。将通过将水蒸气的去耦合方法(Penman-Monteith方程的重新表述)扩展到其他通量(例如，CO？、NO、NO？等)来处理树冠内物质的再循环。通过(A)求解Eger P3反应示踪气体和植物生态Meixner/Falge各自的方程来解析参数分布或使用Taylor展开，以及(B)基于详细的概率密度函数构造有效的一维模式参数，将包括地表异质性和去耦合对放大尺度过程中净通量的影响。

The ability of vegetation canopies to absorb trace gases, which are biogenically emitted by the plants and/or by the soil below, became recently known to be an important aspect of atmospheric budgets of trace gases. The amount of absorbed/escaping trace gases is controlled by (a) physiological and/or surface characteristics of vegetation and soils and (b) interaction of turbulent transport with processes of trace gas exchange, and (c) interaction of turbulent transport with atmospheric chemical transformations. In this respect, a better understanding of de-coupling of in-canopy layers, and coupling between vegetation and atmospheric boundary layer is of crucial importance. Distinct differences between the net vertical transport of H²O and that of CO² or reactive trace gases (NO, NO², O³, NH³, HONO, HNO³) are expected. Therefore, the sub-project aims at measuring and modeling of water fluxes and bi-directional trace gas exchange, as well as interactive coupling of the processes involved; long-term and campaign-wise field measurements are complemented by laboratory studies. Biogenic NO emission from soils will be determined by laboratory experiments. During EGER s Intensive Observation Periods, fluxes from and to soils will be quantified by measurements of the soil air profile and by soil chambers. For the investigation of in-canopy storage, canopy cycling, and whole ecosystem exchange of non-reactive and reactive trace gases vertical profiles of concentrations will be measured as well as in-canopy and above canopy fluxes of reactive trace gases (by eddy covariance and modified Bowen-ratio techniques). In the model, canopy structure is represented by 3D (inhomogeneous) distribution of individual plants, resulting in detailed (m-scale) probability density functions for in- and below canopy scalars and fluxes. In-canopy recycling of matter will be treated by extending the decoupling approach for water vapor (¿-reformulation of the Penman-Monteith equation) to other fluxes (e.g., CO², NO, NO², etc.). Effects of surface heterogeneities and de-coupling on net fluxes during the up-scaling process will be included by (a) solving the EGER P3 Reactive trace gases and plant ecology Meixner/Falge respective equations either analytically for the parameter distributions or using Taylor expansions, and (b) constructing effective 1D model parameterizations based on detailed probability density functions.