Improving Estimates of Horizontal Crustal Motions in Polar Environments

Abstract:

The POLENET/ANET project provides a network of continuously operating GNSS instruments that span the margin of the East Antarctic craton in the Transantarctic Mountains and across the West Antarctic rift system and its component crustal blocks. The network also spans the drainage basin system of the West Antarctic Ice Sheet. GNSS time series of sufficient length are now available to define the horizontal and vertical velocity fields at mm level. However, GNSS signals in Antarctica are commonly affected by polar environmental conditions that result in growth of rime ice on the antenna radome and mast, and intrusion of blowing spindrift snow and accumulation of ice inside chokering antennas even when covered by radomes. In this study we explore the method proposed by Larson (2013) which uses signal to noise ratio (SNR) to flag and remove daily positions impacted by snow or ice on the GNSS antenna/radome. The ‘cleaned’ daily position time series yield velocity solutions with lower RMS. However, at some sites strongly affected by internal antenna ice, the time series is decimated by removal of a significant proportion of daily positions. Improved horizontal velocity estimates better define crustal deformation patterns due to glacial isostatic adjustment and help assess potential displacements related to tectonic motions across the West Antarctic Rift System.