Abstract
AbstractAutomatic feature tracking on two Landsat images (acquired inJanuary 2000 and December 2001) generates a complete and accurate velocity field of Mertz Glacier, East Antarctica. This velocity field shows two main tributaries to the ice stream. Between the tributaries, a likely obstruction feature in the bedrock results in a slow-down of the flow. A third Landsat image, acquired in 1989 and combined with the 2000 image, permits the determination of the glacier mean velocity during the 1990s. Although some parts of the Mertz Glacier system show evidence of slight speed increase, we conclude that the Mertz flow speed is constant within our uncertainty (35 m a−1). Using this complete velocity field, new estimates of the ice discharge flux, 17.8 km3 a−1 (16.4 Gt a−1), and of the basal melting of the tongue, 11 m a−1 of ice, are given. Our results lead to an apparent imbalance of the drainage basin (ice discharge 3.5 km3 a−1 lower than the accumulation). Considering previous studies in the Mertz Glacier area, we then discuss the uncertainty of this imbalance and the problems with accumulation mapping for this region.
Highlights
Ice streams are fast-flowing currents of ice feeding ice shelves or reaching the sea at their terminus (Hughes, 1977)
The Mertz ice stream may have experienced a slight increase in speed during the last decade, but we cannot prove it, so we conclude that the flow of Mertz Glacier is stationary within our uncertainty
From two Landsat images with a 30 m ground resolution, automatic feature tracking allows the determination of the velocity map of Mertz Glacier between February 2000 and December 2001, with an accuracy of 34 m a^1
Summary
Ice streams are fast-flowing currents of ice feeding ice shelves or reaching the sea at their terminus (Hughes, 1977). These ice streams and their complex extensions inland, detected by balance velocity mapping (Bamber and others, 2000), drain most of the accumulation of the Antarctic ice sheet and are critical for its mass balance: they control the output (or discharge fluxes) of the ice sheet. Fast-moving areas of the ice sheet are, with ice shelves, regions where rapid changes can occur. They are an important system to monitor for effects of climate change. Whillans Ice Stream has seen a number of changes in extent, thickness, speed and even direction of flow in its catchment (Bindschadler and Vornberger, 1998; Conway and others, 2002; Joughin and Tulaczyk, 2002)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
