Mapping ice-shelf flow with interferometric synthetic aperture radar stacking

Eero Rinne,Amber Leeson,Jeong-Won Park,Andrew Shepherd,Malcolm Mcmillan,Peter Nienow,Noel Gourmelen

doi:10.3189/2012jog11j072

Abstract

AbstractInterferometric synthetic aperture radar (InSAR) observations of ice-shelf flow contain ocean-tide and atmospheric-pressure signals. A model-based correction can be applied, but this method is limited by its dependency upon model accuracy, which in remote regions can be uncertain. Here we describe a method to determine two-dimensional ice-shelf flow vectors independently of model predictions of tide and atmospheric pressure, by stacking conventional and multiple aperture InSAR (MAI) observations of the Dotson Ice Shelf, West Antarctica. In this way we synthesize a longer observation period, which enhances long-period (flow) displacement signals, relative to rapidly varying (tide and atmospheric pressure) signals and noise. We estimate the error associated with each component of the velocity field to be ~22 ma-1, which could be further reduced if more images were available to stack. With the upcoming launch of several satellite missions, offering the prospect of regular short-repeat SAR acquisitions, this study demonstrates that stacking can improve estimates of ice-shelf flow velocity.

Highlights

Around the coastline of Antarctica, ice shelves provide an interface through which ice is melted by the ocean and the relatively warm coastal air
We have demonstrated that 2-D ice-shelf velocity can be estimated by combining multiple aperture InSAR (MAI) and Interferometric synthetic aperture radar (InSAR) data acquired from a single viewing direction, with comparable errors pertaining to both the velocity vector components
Because the InSAR solutions are tied down using all grounded locations, and not just at point P, this convergence confirms that errors arising from unmodelled topography and baseline effects are small, and that flow remains steady over the period of data acquisition

Summary

Introduction

Around the coastline of Antarctica, ice shelves provide an interface through which ice is melted by the ocean and the relatively warm coastal air Through this connection, changes in atmospheric (Vaughan and Doake, 1996) and oceanic (Rignot and Jacobs, 2002; Shepherd and others, 2004) conditions can trigger an ice-shelf response which, over decadal timescales, can propagate a dynamic instability hundreds of kilometres inland (Payne and others, 2004). Several studies have documented ice-shelf acceleration prior to collapse (Rignot and others, 2004; Vieli and others, 2007) These highlight the importance of monitoring ice-shelf flow velocities, both as an indicator of the stability of the glaciological catchment, and in providing details of the processes through which ice shelves interact with the atmosphere, the ocean and grounded ice upstream (Joughin and Padman, 2003; Payne and others, 2007; Vieli and others, 2007). Until such mechanisms are well understood, the AIS contribution to future sea-level rise remains uncertain

Methods

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Discussion

Conclusion