Scalar Flux Profiles in the Unstable Atmospheric Surface Layer Under the Influence of Large Eddies: Implications for Eddy Covariance Flux Measurements and the Non‐Closure Problem

作者：Heping Liu, Cheng Liu, Jianping Huang, Ankur R. Desai, Qianyu Zhang, Khaled Ghannam, Gabriel G. Katul · 发表于：Geophysical Research Letters · 年份：2023 · DOI：10.1029/2023gl106649 · 被引用次数：15 · 研究领域：Plant Water Relations and Carbon Dynamics、Fluid Dynamics and Turbulent Flows、Meteorological Phenomena and Simulations

Abstract How convective boundary‐layer (CBL) processes modify fluxes of sensible ( SH ) and latent ( LH ) heat and CO 2 ( F c ) in the atmospheric surface layer (ASL) remains a recalcitrant problem. Here, large eddy simulations for the CBL show that while SH in the ASL decreases linearly with height regardless of soil moisture conditions, LH and F c decrease linearly with height over wet soils but increase with height over dry soils. This varying flux divergence/convergence is regulated by changes in asymmetric flux transport between top‐down and bottom‐up processes. Such flux divergence and convergence indicate that turbulent fluxes measured in the ASL underestimate and overestimate the “true” surface interfacial fluxes, respectively. While the non‐closure of the surface energy balance persists across all soil moisture states, it improves over drier soils due to overestimated LH . The non‐closure does not imply that F c is always underestimated; F c can be overestimated over dry soils despite the non‐closure issue.