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
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
复制标题
DOI：
10.1029/2023gl106649
复制
发表时间：
2023-12
影响因子：
5.2
通讯作者：
Heping Liu;Cheng Liu;Jianping Huang;Ankur R. Desai;Qianyu Zhang;K. Ghannam;G. Katul
中科院分区：
文献类型：
--
作者：
Heping Liu;Cheng Liu;Jianping Huang;Ankur R. Desai;Qianyu Zhang;K. Ghannam;G. Katul
对流边界层（CBL）过程如何改变大气近地层（ASL）中感热和潜热（LH）以及CO2（Fc）的通量仍然是一个悬而未决的问题。在这里，大涡模拟的CBL表明，虽然SH在ASL随高度线性下降，无论土壤水分条件下，LH和Fc随高度线性下降，在潮湿的土壤，但随着高度增加，在干燥的土壤。这种变化的通量发散/收敛是由自上而下和自下而上过程之间的不对称通量输送的变化来调节的。这种通量的发散和收敛表明，在ASL测得的湍流通量低估和高估的“真正的”表面界面通量，分别。虽然在所有土壤水分状态下，表面能量平衡的非闭合性持续存在，但由于高估了LH，它在干燥土壤上有所改善。非闭合并不意味着Fc总是被低估;尽管存在非闭合问题，但在干燥土壤上Fc可能被高估。
How convective boundary‐layer (CBL) processes modify fluxes of sensible (SH) and latent (LH) heat and CO2 (Fc) 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 Fc 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 Fc is always underestimated; Fc can be overestimated over dry soils despite the non‐closure issue.