The difference between soil and air temperatures (ΔT) in a specified time is dependent on meteorological conditions, properties of soil and land covers. Understanding ΔT is critical in assessing land–atmosphere thermal interactions in changing environment. However, systematic knowledge of interannual variations and responses of ΔT to the environmental changes (e.g., snow cover and soil moisture) at decadal scales remain limited. Here, variations of the mean annual air and soil temperatures, and ΔT were investigated at 217 sites in northern Eurasia during 1981–2015. It is found that changes in the mean annual air and soil temperatures were inconsistent as the average increase in soil temperature was generally less than that of air. The relationships between trends in soil and air temperatures were significant in the upper ground (0.2 and 0.8 m) over the seasonal frost region but insignificant in the permafrost regions and deeper ground. During the period, widespread changes in ΔT occurred and closely responded to the environmental changes, but the relationships varied with soil depth. Among the tested factors, trends in snow cover thickness dominantly control trends in ΔT, followed by trends in snow cover duration and solar radiation. Both linear and nonlinear analyses indicate enhanced relationships between trends in snow depth and ΔT as depth increases. This study provides the first view of decadal trends in ΔT and conjunctions with the environmental changes during 1981–2015 over northern Eurasia. The findings are relevant to quantify land–atmosphere thermal interactions given impacts of future environmental changes.

中文翻译：

---

欧亚大陆北部土壤和大气温度差异的年代际变化与环境变化相关

在指定时间内土壤和空气温度（ΔT）之间的差异取决于气象条件，土壤和土地覆盖的性质。了解ΔT对于评估不断变化的环境中的土地-大气热相互作用至关重要。然而，在十年尺度上，年际变化和ΔT对环境变化（例如，积雪和土壤湿度）的响应的系统性知识仍然有限。这里，年平均气温和土壤温度以及ΔT的变化在1981-2015年期间对欧亚大陆北部的217个地点进行了调查。发现平均年气温和土壤温度的变化不一致，因为土壤温度的平均升高通常小于空气的平均升高。在季节性霜冻地区，上部地面（0.2和0.8 m）的土壤和气温趋势之间的关系很明显，而在多年冻土地区和更深的地区，土壤和气温的趋势无关紧要。在此期间，ΔT发生了广泛的变化，并与环境变化密切相关，但其关系随土壤深度而变化。在测试的因素中，积雪厚度的趋势主要控制着ΔT的趋势。，其次是积雪持续时间和太阳辐射的趋势。线性和非线性分析均表明，随着深度的增加，雪深趋势与ΔT之间的关系增强。这项研究提供了1981年至2015年欧亚大陆北部ΔT年代际趋势以及与环境变化相关的第一个观点。考虑到未来环境变化的影响，这些发现与量化土地-大气的热相互作用有关。