Abstract Knowledge of soil–vegetation–atmosphere energy exchange processes is essential for examining the response of agriculture to changes in climate in both the short and long term. However, there are relatively few sites where all the flux measurements necessary for evaluating these responses are available; where they exist, data are often incomplete and/or of limited duration. At the same time, there is often an extensive observation network available that has gathered key meteorological data (sunshine, wind, rainfall, etc.) over decades. Simulating the terms of the surface energy balance (SEB) using available meteorological, soil and vegetation data can improve our understanding of how agricultural systems respond to climate and how this response will vary spatially. Here, we employ a physically-based scheme to simulate the SEB fluxes over a mid-latitude, maritime temperate environment using routine weather observations. The latent heat flux is a critical SEB term as it incorporates the response of the plant to environmental conditions including available energy and soil water. This response is represented in modeling schemes through surface resistance (rs), which is usually expressed as a function of near-surface water vapor alone. In this study, we simulate the SEB over two grassland sites, where eddy flux observations are available, representing imperfectly- and poorly- drained soils. We employ three different formulations of rs, representing varying degrees of sophistication, to estimate the surface fluxes. Due to differences in soil moisture characteristics between the sites, we ultimately focused our attention on an rs formulation that accounted for soil water retention capacity, based on the Jarvis conductance model; the results at both hourly and daily intervals are in good agreement, with RMSE values of ≈ 40 W m−2 for sensible and latent heat fluxes at both sites. The findings show the potential value of using routine weather observations to generate the SEB where flux observations are not available and the importance of soil properties in estimating surface fluxes. These findings could contribute to the assessment of past and future climate change on grassland ecosystems.

中文翻译：

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改进土地表面方案，以估算具有对比土壤湿度区的草地上方的感热和潜热通量

摘要 土壤-植被-大气能量交换过程的知识对于研究农业对短期和长期气候变化的响应至关重要。然而，能够获得评估这些响应所需的所有通量测量值的站点相对较少；如果存在，数据往往不完整和/或持续时间有限。与此同时，通常有一个广泛的观测网络，可以收集几十年来的关键气象数据（阳光、风力、降雨等）。使用可用的气象、土壤和植被数据模拟地表能量平衡 (SEB) 项可以提高我们对农业系统如何响应气候以及这种响应如何在空间上变化的理解。这里，我们采用基于物理的方案，使用常规天气观测模拟中纬度海洋温带环境中的 SEB 通量。潜热通量是一个关键的 SEB 术语，因为它包含了植物对环境条件（包括可用能量和土壤水分）的响应。这种响应在建模方案中通过表面电阻 (rs) 表示，通常仅表示为近地表水蒸气的函数。在这项研究中，我们模拟了两个草地站点的 SEB，在这些站点上可以获得涡流观测，代表不完全排水和排水不良的土壤。我们采用三种不同的 rs 公式，代表不同程度的复杂性，来估计表面通量。由于站点之间土壤水分特征的差异，我们最终将注意力集中在基于 Jarvis 电导模型的考虑土壤保水能力的 rs 公式上；每小时和每天的结果都非常一致，两个站点的感热和潜热通量的 RMSE 值都为 ≈ 40 W m-2。研究结果显示了在无法进行通量观测的情况下使用常规天气观测生成 SEB 的潜在价值，以及土壤特性在估算地表通量中的重要性。这些发现可能有助于评估草原生态系统过去和未来的气候变化。对于两个站点的感热和潜热通量，RMSE 值 ≈ 40 W m-2。研究结果显示了在无法进行通量观测的情况下使用常规天气观测生成 SEB 的潜在价值，以及土壤特性在估算地表通量中的重要性。这些发现可能有助于评估草原生态系统过去和未来的气候变化。对于两个站点的感热和潜热通量，RMSE 值 ≈ 40 W m-2。研究结果显示了在无法进行通量观测的情况下使用常规天气观测生成 SEB 的潜在价值，以及土壤特性在估算地表通量中的重要性。这些发现可能有助于评估草原生态系统过去和未来的气候变化。