Radio-echo layering in polar ice sheets ...

• Main Author: Millar, David H M
• Format: Thesis
• Language: English
• Published: Apollo - University of Cambridge Repository 1981
• Subjects: Antarc*; Antarctic; Greenland; Ice Sheet
• Online Access: https://dx.doi.org/10.17863/cam.14157; https://www.repository.cam.ac.uk/handle/1810/268045

This thesis is concerned with layered reflections observed in the Antarctic and Greenland ice sheets during radio-echo sounding. It describes in detail layering seen with 60 and 300 MHz equipment _in the Antarctic ice sheet during three field seasons betwe~n 1974 and 1979, and discusses the effects of glaciological and equipment factors, particularly radio pulse length. The effects of changing pulse length and accumulation rate on layer echo separation are analysed, and the importance of closely spaced groups of reflectors assessed. Reflection coefficient vs depth profiles are presented for layering observed at nearly twenty sites in the Antarctic and Greenland, and are used to demonstrate the existence of two separate reflection mechanisms: changes in (a) ice density, and (b) loss tangent. Supporting density and conductivity data from ice cores are summarised. It is concluded that most layer echoes arise from layers of ice containing acidic impurities of volcanic origin~ Layer reflectivity variations_are ...