Investigation of permafrost in Chandratal lake area

Abstract

This study evaluated the presence of permafrost in the Chandratal Lake region using the GEOtop model. The model was simulated using field soil temperature (10cm depth) data collected from 11 T-Loggers around the lake from September 2020 to June 2024. Furthermore, bias-corrected hourly soil temperature (Level 1 and Level 2) ERA5 data from 1991 to 2024 were used for model simulation to understand the temporal variation of soil thermal profile along the depth over three decades. The model was run using high and low thermal diffusivity for soil to get an envelope of thermal profiles of soil along the depth. The field data was used to determine the snow melt-out date for the locations of T-Loggers over three years (2021 to 2023). The study revealed an absence of permafrost in the lakes surrounding as the soil temperature stabilizes above 3.35oC in both high and low thermal diffusivity cases. This is in contrast to the previous remote sensing and air temperature-based studies that hinted at permafrost's presence in the region. These results raise the potential question of whether we are overestimating the presence of permafrost by using indirect parameters for the soil thermal profile instead of actual ground temperature.