Title: Impact of Heterogeneity on Scalar Flux Variance Relations Across Diverse Ecosystems Show Chinese title

Title: 异质性对不同生态系统中标量通量方差关系的影响

Abstract: Traditional surface layer theory to understand the behavior, scaling and exchange of heat, water vapor and carbon dioxide between the land surface and atmosphere relies on a number of commonly broken assumptions. In particular, traditional theory breaks down under three different forms of heterogeneity highlighted in this work: spatial heterogeneity in the sources of the scalars, heterogeneity in the Reynolds stress tensor (turbulence anisotropy), and temporal heterogeneity (non-stationarity). The work explores the relationship between the idealized flux-variance relations and these three forms of heterogeneity across a diverse network of 47 flux towers representing a broad range of ecosystems including forests, agricultural land, grasslands, tundra, tropical and arid: the National Ecological Observation Network (NEON). Results use high resolution spatial data (1 meter resolution) to show a direct relationship between spatial heterogeneity and deviation from traditional scaling relations. Prior work indicates a close relationship between turbulence anisotropy and velocity scaling. A similar result shows weaker, albeit significant differences in the surface layer scaling for all three variables under both stable and unstable stratification based on turbulence anisotropy. The study also indicates an interplay between stationarity and anisotropy, with the non-dimensionalized scalar variance scaling more strongly with anisotropy under more non-stationary turbulence. Updated flux-variance relations that leverage turbulence anisotropy for the scaling of temperature are introduced, as are novel anisotropy-generalized scalings for water vapor and carbon dioxide. The novel scalings show significant improvement over traditional relations. The work also explores in detail how the scaling relations, and their relationship with heterogeneity, vary across the diverse sites in the NEON network. Show Chinese abstract

Abstract: 传统的地表层理论用于理解地表与大气之间热量、水汽和二氧化碳的行为、尺度和交换，依赖于一些通常被打破的假设。 特别是，传统理论在本文强调的三种异质性形式下失效：标量源的空间异质性、雷诺应力张量（湍流各向异性）的异质性以及时间异质性（非平稳性）。 这项研究探讨了理想化的通量方差关系与这三种异质性之间的关系，覆盖了一个由47个通量塔组成的多样化网络，代表了包括森林、农田、草地、苔原、热带和干旱地区在内的广泛生态系统：国家生态观测网络（NEON）。 结果使用高分辨率空间数据（1米分辨率）显示了空间异质性与传统尺度关系偏差之间的直接关系。 先前的研究表明湍流各向异性与速度尺度之间存在密切关系。 类似的结果显示，在稳定和不稳定分层条件下，基于湍流各向异性的所有三个变量的地表层尺度存在较弱但显著的差异。 该研究还表明平稳性和各向异性之间存在相互作用，在更不平稳的湍流下，无量纲标量方差与各向异性的尺度关系更强。 引入了利用湍流各向异性进行温度尺度化的更新后的通量方差关系，同时还提出了水汽和二氧化碳的新型各向异性广义尺度。 这些新型尺度相对于传统关系有显著改进。 这项工作还详细探讨了尺度关系及其与异质性的关系如何在NEON网络中的不同站点之间变化。