Variations in ice velocities of Pine Island Glacier Ice Shelf evaluated using multispectral image matching of Landsat time series data

Abstract

Pine Island Glacier (PIG) in West Antarctica drains out to the Amundsen Sea through Pine Island Glacier Ice Shelf (PIGIS). As changes in ice velocities on PIGIS are strongly linked to changes in ice mass discharge from the West Antarctic Ice Sheet, it is very important to evaluate the spatiotemporal variations in ice velocities on the ice shelf. This research estimated ice velocities of PIGIS from an ensemble of image matching of Landsat time series multispectral data obtained from 2000 to 2014. Orientation correlation was adopted for the image matching of blue, green, red, near infrared, panchromatic, and the first principal image of the Landsat multispectral data, from which the results were combined and averaged. The multispectral image matching proposed in this research produced ~35% more ice velocity vectors than the use of a single band (i.e., panchromatic band) image matching. The erroneous matches were filtered through simple but rigorous statistical evaluations. The ice velocity of PIGIS accelerated by ~55% during 2000-2010, and the acceleration of the image northing velocity component (~1.3 km a^-1) was higher than that of the image easting velocity component (~0.8 km a^-1). During 2010-2012, the ice velocity of PIGIS slowed down by ~10%. The ice velocity in 2014 increased by 5% from 2012, but was still lower than the peak values observed in 2010. The surface strain rate fields of PIGIS were derived from the ice velocity fields. The longitudinal ice compression was observed near the grounding line and the geographically northern part of the central ice shelf of PIGIS, while a fast-flowing band was observed near the southern margin of the ice shelf. The transverse strain rate showed that ice divergence in the hinge zone of the central ice shelf has increased since 2000. The width of the shear margins of the central ice shelf of PIGIS is ~25 km, which has been stable since 2000.