Physical Simulation of Maximum Seasonal Soil Freezing Depth in the United States Using Routine Weather Observations

Abstract

An existing, physically based soil freezing model applicable to humid climates is modified for use in the central and western United States. Simulations using the state-of-the-art Simultaneous Heat and Water (SHAW) model indicated that the original model required the addition of a water budgeting scheme and alteration of the equation for soil thermal conductivity. Using only daily temperature, liquid precipitation, snowfall, and snow cover, this new model allows the simulation of maximum seasonal frost depths at several thousand U.S. stations. Comparison of the model-derived maximum frost depths with observed and soil temperature?inferred soil freezing maxima at 32 arid and semiarid locations indicates excellent agreement. Observed maximum soil freezing depths, ranging from 0 to over 100 cm, are simulated, with an average absolute error of 5.4 cm. At individual stations, the seasonal penetration and thawing of soil freezing tracks that of the observations very closely, regardless of ambient soil moisture conditions.