Yanzhao Zhou , Heping Liu , Matthias Sühring , Xin Li
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引用次数: 0
Abstract
The non-closure of surface energy balance, often encountered in eddy covariance (EC) measurements, raises a critical query: does this non-closure lead to underestimated scalar fluxes, particularly CO2 flux (Fc), when using the same theoretical framework in EC? To address this question, we utilize high-resolution large-eddy simulations (LESs) to explore correlations between energy flux imbalances and Fc imbalances in convective boundary layers, considering both homogeneous and idealized heterogeneous surfaces. Our findings reveal that the unsteady CO2 or storage represents a leading factor influencing Fc imbalance, especially notable when the entrainment ratio for Fc is large. Even in scenarios with uniform surface Fcs, heterogeneous thermally-generated turbulence resulting from variable surface sensible heat flux (H) can induce substantial horizontal flux divergence, magnifying Fc imbalance. While a linear correlation between the energy flux imbalance and Fc imbalance arises under shared causative mechanisms (e.g., storage), complex correlations emerge if their influencing factors differ, contingent upon surface heterogeneity and site location. This complexity underscores the limitations in applying the closing methods for energy flux imbalance to the Fc imbalance.
在涡度协方差(EC)测量中经常遇到地表能量平衡不封闭的情况,这就提出了一个关键问题:当在 EC 中使用相同的理论框架时,这种不封闭是否会导致低估标量通量,特别是 CO 通量(Fc)?为了解决这个问题,我们利用高分辨率大涡流模拟(LES)来探索对流边界层中能量通量失衡与 Fc 失衡之间的相关性,同时考虑了同质表面和理想化异质表面。我们的研究结果表明,非稳态 CO 或存储是影响 Fc 不平衡的主要因素,当 Fc 的夹带率较大时尤其明显。即使在表面 Fcs 一致的情况下,由于表面显热通量(H)可变而产生的异质热湍流也会导致大量水平通量发散,从而放大 Fc 不平衡。虽然能量通量失衡和 Fc 失衡在共同的致因机制(如储存)下呈线性相关,但如果它们的影响因素不同,则会出现复杂的相关性,这取决于地表异质性和站点位置。这种复杂性凸显了将能量通量失衡的闭合方法应用于 Fc 失衡的局限性。
期刊介绍:
Agricultural and Forest Meteorology is an international journal for the publication of original articles and reviews on the inter-relationship between meteorology, agriculture, forestry, and natural ecosystems. Emphasis is on basic and applied scientific research relevant to practical problems in the field of plant and soil sciences, ecology and biogeochemistry as affected by weather as well as climate variability and change. Theoretical models should be tested against experimental data. Articles must appeal to an international audience. Special issues devoted to single topics are also published.
Typical topics include canopy micrometeorology (e.g. canopy radiation transfer, turbulence near the ground, evapotranspiration, energy balance, fluxes of trace gases), micrometeorological instrumentation (e.g., sensors for trace gases, flux measurement instruments, radiation measurement techniques), aerobiology (e.g. the dispersion of pollen, spores, insects and pesticides), biometeorology (e.g. the effect of weather and climate on plant distribution, crop yield, water-use efficiency, and plant phenology), forest-fire/weather interactions, and feedbacks from vegetation to weather and the climate system.