In situ measured and simulated seasonal freeze–thaw cycle: A 2-year comparative study between layered and homogeneous field soil profiles

Abstract

Summary Annual freeze–thaw cycles of soil significantly impact agricultural and ecosystem services in cold regions. For advancing our understanding of freeze–thaw process, both improved measurements and simulations of coupled-heat-water-transfer (CHWT) phenomenon are needed under different field conditions. This paper focused on a comparative study between a CHWT-model simulation versus in situ measurements of liquid soil water content (LSWC) and soil temperature (ST) at two agricultural field sites. The first site consisted of a layered soil profile with sandy silt loam (0–60 cm) and clay loam (60–130 cm) layers, and the other site was a uniform sand profile (0–110 cm). Measurements were made over two winters between 2011 and 2013, i.e. the first winter is 2011–2012 (year 1) and the second winter is 2012–2013 (year 2), in the northeast of China employing an access-tube dielectric sensor combined with a temperature measurement array. During the freezing period of the year 1 winter, the soil freezing characteristic curves (SFCCs) were determined in situ in relation to the site-specific data of LSWC and ST and subsequently used for the model calibration. For the thawing process of year 1 and the freeze–thaw process of year 2, the resulting ST simulation time series were well-correlated with field measurements. In terms of the resulting LSWC, the numerical simulations also correlated well (R2 > 0.895, RMSE 0.702, RMSE