Corrections To "Radiometric Sensitivity Computation In Aperture Synthesis Interferometric Radiometry"

(a) (b) Fig. 3. (a) Observation of " 00 change of ice slab on duraluminum mold at 13. the other hand, quick freezing may produce a specific distribution of salt concentration in ice volume. However, the main result of the measurements, as it follows from Figs. 2 and 3, is the hysteresis of " 00 in the case of slow-cycle temperature change for many days. Our other experiments with different temperature conditions and with long-time measurements also indicated the effect of ambiguity of electromagnetic losses. The discussion on hysteresis of the real part of ice dielectric permittivity at 1 kHz was published earlier in [7]. It was observed for the ice that formed the 2% NaCl solution. This experiment lasted for about an hour. However, this observation was interpreted as the influence of the heat of phase transition. In our experiments, the analogous explanation is not true because there was a small amount of salt and a long period of keeping ice at a low-ambient temperature. We conclude that the hysteresis effect in our experiments may be connected with the existence of supercooling salt microscopic inclusions at temperatures lower than eutectic point, where they are in a liquid state. The possible supercooling temperature is determined by the shape and the size of liquid inclusions. It seems that their metamorphism determine the volume-liquid concentration and, consequently, the imaginary part of dielectric permittivity. The determination of the exact origin of electromagnetic-loss ambiguity requires a more detailed investigation of freshwater ice structure and physical and chemical peculiarities of inclusions. V. CONCLUSIONS There are significant time changes of the imaginary part of dielec-tric permittivity even for constant-value salt-impurity concentration in freshwater ice. Different values of electromagnetic loss were experimentally observed at the identical temperature. Thus, for the determination of ice dielectric loss, we must take into account the ice-time existence after water is frozen, the ice-temperature history, and the inclusions characteristics. Disregarding these conditions in previous papers led not so much to measurement errors, but to the description of ice with different structures. Therefore, the cryosphere remote sensing requires taking into account the time changeability of ice electromagnetic properties. REFERENCES [1] A. Stogryn, " A study of the microwave brightness temperature of snow from the point of strong fluctuation theory, " IEEE Trans. Influence of some salt components and its composition on ice electrical properties, " Proc. Arct. Antarct. Abstract— This paper is concerned …