Alaska-COLD: Linking Surface Temperatures and Subsurface Thermal Dynamics in a Multi-Year Hourly Dataset From Interior and Northern Alaska

Abstract. We present the Alaska Coupled Observations of Land-atmosphere Dynamics (Alaska-COLD) dataset, comprising hourly air and soil temperature measurements from 12 sites across Alaska's north-central regions (64°–70°N). Each site measures air temperature and soil temperatures at four depths (0–0.7 m). Seven sites provide 714–726 days of continuous records (Summer 2023–2025) capturing multiple freeze-thaw (FT) cycles. We classify FT phenology into thawing, thawed, freezing, and frozen phases using surface temperature observations, enabling phase-specific analysis of thermal dynamics. We further derive FT metrics, including n-factors, degree-day totals, and damping ratios, to characterize surface energy exchange and subsurface thermal attenuation. The records reveal strong thermal damping with depth: surface-soil diurnal amplitudes range from 0.7–4.3°C, while the deepest sensors show only 0.004–0.047°C variation across the mean daily cycle. At the annual scale, ground-temperature ranges decrease from 11–25°C near the surface to 3–5°C at 45–75 cm depth, compared with air temperature ranges of 36–45°C. Thawed periods range from 39 to 92 days annually, and air-ground coupling vary strongly by FT phase, with R2 increasing from 0.02 during thawing to 0.69 during thawed conditions. A concise comparison with colocated ERA5-Land estimates shows stronger agreement for air temperature than for soil temperatures, highlighting the value of Alaska-COLD for resolving site-level ground thermal dynamics in permafrost environments. Alaska-COLD is accessible via: https://doi.org/10.5281/zenodo.17980271.