In order to mitigate spring frost damage to wheat in the Huanghuaihai region, this paper developed a combined frost index (CFI) based on daily meteorological observations collected from 46 stations between 2000 and 2020, along with wheat yield data. Grounded in the Soil-Plant-Atmosphere Continuum (SPAC) theory, which encompasses meteorological, soil, and crop factors, the study employed a combination assignment method based on ideal points to allocate indicators. Subsequently, this study delves into the spatial and temporal distribution characteristics of frost events in the Huanghuaihai region and carefully assesses the risk of frost damage in the region. The findings indicate that: (1) CFI was a significant predictor of relative meteorological yield in wheat across various growth stages, with a highly significant negative correlation observed, thus verifying the index's validity. (2) The results of our analysis indicated significant inter-annual variations in the wheat frost index (Tz), with particularly abrupt changes observed during the early and late spring frost events of 1997 and 2009. (3) The spatial distribution of wheat frost damage during the two growth stages exhibited distinct regional disparities, with a consistent northward increase in severity, predominantly concentrated in the northern part of the Huanghuaihai region.

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.