Sea Ice Thickness Measurements By Ultrawideband Penetrating Radar: First Results

摘要

This study evaluates the potential of ultrawideband penetrating radar for the measurement of sea ice thickness. Electromagnetic modeling and system simulations were first performed to determine the appropriate radar frequencies needed to simultaneously detect both the top ice surface (snow-ice interface) and to penetrate through the lossy sea ice medium to identify the bottom ice surface (ice-ocean interface). Based on the simulation results, an ultrawideband radar system was built that operated in two modes to capture a broad range of sea ice thickness. The system includes a low-frequency mode that operates from 50-250 MHz for measuring sea ice thickness in the range of 1 to 7 m (both first-year and multiyear ice types) and a high-frequency mode that operates from 300-1300 MHz to capture a thinner range of thickness between 0.3 and 1 m (primarily first-year ice type). Two field tests of the radar were conducted in 2003, the first off Barrow, Alaska, in May and the second off East Antarctica in October. Overall the radar measurements showed a mean difference of 14 cm and standard deviation of 30 cm compared with in situ measurements over first-year ice that ranged from 0.5 to 4 m in thickness. Based on these initial results, we conclude that ultrawideband penetrating radar is feasible for first-year sea ice thickness measurements. We discuss approaches for further system improvements and implementation of such a system on an airborne platform capable of providing regional sea ice thickness measurements for both first-year and multiyear ice from 0.3 to 10 m thick.