Nitrous acid (HONO) source and sink processes in a disturbed forest ecosystem - interactions of heterogeneous chemistry and turbulent transport

在这个项目中，将研究一个受干扰的森林生态系统中亚硝酸（HONO）源和汇过程的复杂相互作用。在以前的野外实验中，没有观察到大气中HONO和NO2（最可能的前驱物）的混合比之间存在紧密的相关性，而非均相化学（对湿度条件有很强的依赖性）和湍流输送的相互作用则发挥了重要作用。拟议的测量将之前在森林中对HONO的实地测量扩展到森林砍伐的第二个对比地点。新的近地表剖面测量将有助于对相关HONO源和汇的时间演变和空间分布进行更深入的评估。拟议的研究任务旨在填补从我们的森林生态系统研究地点分析HONO现场数据时明显出现的科学空白。特别是，我们的目标是在不同的大气耦合制度下解开非均相化学（受辐射和湿度条件的影响）和湍流输送的相互作用。该项目还将有助于对扰动森林生态系统湍流运移的基本认识，并为评价和加强林冠尺度上的反应性微量气体模拟提供基础观测数据。

Within this project, the complex interplay of source and sink processes of nitrous acid (HONO) will be studied in a disturbed forest ecosystem. In previous field experiments, a tight correlation of the atmospheric mixing ratios of HONO and NO2, the most probable precursor, was not observed, while the interaction of heterogeneous chemistry (with a strong dependence on humidity conditions) and turbulent transport was found to play a significant role. The proposed measurements extend the previous field measurements of HONO within the forest to a second contrasting site in a forest clear cut. New near-surface profile measurements of HONO, NO, NO2 and O3 within the lowest two meters above the ground both in the trunk space and the clear cut will contribute to an advanced assessment of the temporal evolution and spatial distribution of relevant HONO sources and sinks. The proposed research tasks are designed to fill the scientific gaps that became evident from analyzing HONO field data from our forest ecosystem research site. In particular, we aim at untangling interactions of heterogeneous chemistry (influenced by radiation and humidity conditions) and turbulent transport under different atmospheric coupling regimes. This project will also contribute to the fundamental understanding of turbulent transport in a disturbed forest ecosystem, and provide basic observational data to evaluate and enhance reactive trace gas modeling on the canopy scale.