Department of Applied Physics,Faculty of Engineering, Hokkaido University
Abstract
Step frequency radar experiments have been carried out on sea ice near Syowa Station as part of the 27th Japanese Antarctic Research Expedition to develop an airborne sensor for measuring vertical sea ice structures. Step frequency radar has characteristics of high resolution and low frequency (UHF band), which is an advantage in measuring sea ice. The experiments are the first application of this radar for measuring sea ice thickness. The radar transmits 32 different frequencies in a stepwise fashion between 300 and 796 MHz and measures the amplitude and phase of reflected waves at each frequency. The discrete Fourier transform of the 32 complex values of signals indicates the distance of vertical sea ice structures. The range resolution is about 15cm in sea ice. The experimental results showed that the radar system could successfully measure vertical sea ice structures : (1) The distance between the surface and the snow/ice interface or between the surface and the sea ice bottom deduced by this method coincided with direct measurements in sample holes. (2) Snow depth was measured very clearly by the radar system
