Comparison of Various Models of Supercooled Water-Loss Factor with Experimental Data in the Microwave Range

An improved formula for the supercooled water-loss factor at frequencies of 10–180 GHz in the temperature range –70 to 0°C is presented. The formula is based on the experimental data obtained by the authors on the measurements of attenuation in the pore water of silicate materials. The formula contains two terms describing the Debye dependence of the loss factor on frequency and temperature and non-Debye dependence determined by the influence of the second critical point of water. The proposed formula is compared with the model formulas of other authors. A significant discrepancy (by several times) between the calculation results of the loss factor at frequencies above 100 GHz and temperatures below –30°C is established. The model based on the measurements provides the most adequate representation of the behavior of the loss factor with an error of ~30% in the region of deeply supercooled water and in the upper part of the studied frequency range.