Abstract

Global climate change in recent decades is accompanied by rising temperatures and increasing cyclonic activity with strong air flows. How do they affect soil respiration? Is it possible to expect an increase in CO₂ emissions and, consequently, a positive feedback of climate change through the greenhouse effect? These questions cannot be answered without the insight into the effect of wind speed on the gas exchange between soil and atmosphere in different landscapes. The paper summarizes the long-term measurements of CO₂ efflux from forest-steppe chernozems (Kursk oblast, Russia) in natural and anthropogenic landscapes with forest or herbaceous vegetation depending on wind speed; it presents a physically grounded approach to its quantitative first-approximation (linear) description. The approach assumes an impact of wind through increased forced convection and turbulent diffusivity along with a potential reduction in diffusion mass transfer due to a decrease in the gradient of CO₂ concentration between the atmosphere and soil. The constructed inverse parabolic dependence adequately describes the empirical data and assumes a twofold increase in the emission with the wind speed increase to the critical value of 3 m/s and its decreases to the initial level with the further wind speed increase to 6–7 m/s. The intensity of forced convection of soil air turns out to be by five–six orders of magnitude lower than the wind speed in the atmosphere but not inferior to the intensity of conventional isothermal CO₂ diffusion, which suggests that this mechanism is to be taken into account in the models of soil–atmosphere gas exchange.

中文翻译：

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风对土壤-大气气体交换的影响

摘要

近几十年来，全球气候变化伴随着温度升高和强气流导致的旋风活动增加。它们如何影响土壤呼吸？是否有可能期望增加CO ₂排放量，并因此通过温室效应获得积极的气候变化反馈？如果不了解风速对不同景观中土壤与大气之间气体交换的影响，就无法回答这些问题。本文总结了CO ₂的长期测量在自然和人为景观中，森林草原黑钙土（俄罗斯库尔斯克州）的外流，取决于风速；它为定量的第一近似（线性）描述提供了一种基于物理的方法。该方法假设通过增加强制对流和湍流扩散率对风的影响，以及由于CO ₂梯度降低而导致的扩散传质的潜在减少。大气和土壤之间的浓度。构造的抛物线逆相关性充分描述了经验数据，并假设排放随风速增加到临界值3 m / s而增加了两倍，并随着风速进一步增加到6-7 m而减少到了初始水平。 / s。事实证明，土壤空气的强制对流强度比大气中的风速低五到六个数量级，但不低于常规等温CO ₂扩散的强度，这表明应将此机理考虑在内在土壤-大气气体交换模型中有解释。