Amount of soil ice predicted from weather observations

Abstract

An equation has been developed that gives the net daily heat flux across the soil surface in the winter. The equation is based on the Fourier heat flow relation using the thermal gradients and conductivity at the soil surface. Input requires the daily maximum/minimum air temperatures, solar radiation and snow depth. The cumulative daily soil heat flux was used to estimate the amount of ice in the soil. Several years of data from weather stations near Lafayette, Indiana, and Twin Falls, Idaho, were used to test this approach. Given a site constant that accounts for soil type and cover conditions, it appears that the presence or absence of soil ice can generally be correctly predicted at least 70% of the time over a period of years that includes both warm and cold extremes.