DIELECTRIC PROPERTIES OF ICE CONTAINING ACID AND SALT IMPURITIES AT MICROWAVE FREQUENCIES

• Main Authors: マツオカ タケシ, フジタ シュウジ, マエ シンジ, Takeshi MATSUOKA, Shuji FUJITA, Shinji MAE
• Format: Report
• Language: English
• Published: ABSTRACT 1997
• Subjects: Polar meteorology and glaciology; Proceedings of the NIPR Symposium on Polar Meteorology and Glaciology
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=3992; http://id.nii.ac.jp/1291/00003992/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=3992&item_no=1&attribute_id=18&file_no=1

To clarify the effects of ionic impurities on the dielectric properties of ice, the relative complex dielectric permittivities (ε^*=ε′-iε″) of ice containing acid and salt impurities were measured in a wide temperature range from -80 to -2℃ using the cavity resonator method at 5GHz. The dielectric properties of ice at microwave frequencies are necessary for understanding remote sensing signatures in polar regions, obtained by ice-radar and satellite-borne microwave radar and radiometer. Especially, the dielectric loss, ε″, of ice is an important parameter to understand the attenuation of electromagnetic waves in ice sheets. In the measurements, the ice samples contained the acids H_2SO_4 and HNO_3,and the salt NaCl. The impurity concentration was between (10)^<-5> and (10)^<-3>M (molarity). The results are as follows : The dielectric loss, ε″, of ice increased with the increases in temperature and contained impurity concentration. A sharp increase in ε″of ice containing (10)^<-4>M H_2SO_4,HNO_3 and NaCl was observed immediately above the eutectic points -73℃, -43℃ and -21℃, respectively. The sharp change shows that the aqueous solution of the contained impurity is formed in grain boundaries and triple junctions of the polycrystalline ice above the eutectic point. The penetration depths of microwaves at 5GHz into ice containing H_2SO_4,HNO_3 and NaCl were estimated from the temperature and concentration dependence of the dielectric permittivities.