Simulated Spatial and Temporal Distribution of Freezing and Thawing Fronts in CAS-FGOALS-g3

Abstract

In this study, we implement a new frozen-soil parameterization scheme into the climate system model CAS-FGOALS-g3 to investigate the dynamic changes of freezing and thawing fronts and the effects arising from thermal processes and climate. Simulations are conducted using the developed model to validate its performance relative to multi-source observations. It is shown that the model could reasonably reproduce soil freezing and thawing processes, including dynamic changes in freezing and thawing fronts. The historical simulation shows that the maximum freeze depth increases with an increase of latitude in seasonally frozen ground, and the active layer thickness decreases with an increase of latitude in permafrost regions. The active layer thickness shows increasing trends while the maximum freeze depth shows decreasing trends, which is consistent with change in the 2-m air temperature. In conclusion, these results have the potential to further deepen our understanding of the freeze-thaw cycle process and the historical response of permafrost to climate change.