Yellow River source region of the Qinghai-Tibet Plateau. Understanding soil temperature dynamics in frozen regions is crucial for investigating the thermal, hydrological, and ecological processes in cold regions. Using multi‑depth in‑situ observation data, this study investigates the variations of soil temperature and their responses to environmental factors in typical permafrost and seasonally frozen sites. Results show that the permafrost and seasonally frozen sites exhibit distinct temperature variations and freeze-thaw processes. Based on temperature amplitude and variability, a three-layer thermal structure at all sites is identified. For the active layer (0–200 cm), soil temperature gradient and thermal responses show pronounced diurnal variations, and each frozen site exhibits significantly distinct soil temperature dynamics. Seasonally frozen sites showed stronger diurnal variability than permafrost sites, particularly during cold periods. Additionally, cross-wavelet analysis reveals that air temperature is the dominant driver of soil temperature dynamics at multiple timescales (4–128 days), with strong coherence and stable positive phase relationships, whereas precipitation, evaporation, and soil moisture show weaker and more intermittent effects. These findings provide quantitative insights into soil thermal behavior under varying climatic conditions and offer a foundation for future modelling of soil hydrothermal processes and permafrost evolution in response to climate change. • Systematic thermal difference is quantified between permafrost and seasonal frost. • Seasonally frozen site shows stronger diurnal variability within the active layer. • Cross-wavelet analysis reveals depth-dependent frequency selectivity.
Wu et al. (Thu,) studied this question.