Estimation of Soil Freezing Date Using Air Temperature Remotely Measured.

Soil freezes in the winter of Iitate Village in Fukushima Prefecture. When soil freezes with an appropreate deoth, it seems to be a perfect timing for removing the soil surface layer that contains most of radiocaesium fallout. We monitored air- and soil-temperatures at 20 differnt places all over Iitate Village so that we may estimate soil freezing date to start radiocaesium-contaminated-soil removal operation. Cummulative air temperature below zero was calculated for a reference site. At the reference site, soil freezing was detected using a soil moisture sensor installed at 5cm deep because the dielectric constant of ice was similar to that of soil particle.