Abstract
Abstract. As part of the Greenland Ice Mapping Project (GIMP) we have produced three geospatial data sets for the entire ice sheet and periphery. These are (1) a complete, 15 m resolution image mosaic, (2) ice-covered and ice-free terrain classification masks, also posted to 15 m resolution, and (3) a complete, altimeter-registered digital elevation model posted at 30 m. The image mosaic was created from a combination of Landsat-7 and RADARSAT-1 imagery acquired between 1999 and 2002. Each pixel in the image is stamped with the acquisition date and geo-registration error to facilitate change detection. This mosaic was then used to manually produce complete ice-covered and ice-free land classification masks. Finally, we used satellite altimetry and stereo-photogrammetric digital elevation models (DEMs) to enhance an existing DEM for Greenland, substantially improving resolution and accuracy over the ice margin and periphery.
Highlights
The objective of the Greenland Ice sheet Mapping Project (GIMP) is to establish benchmark data sets for observing ice sheet change
We focus on generating a continuous surface and we ignore temporal changes in ice elevation, which are over 100 m near the fronts of some rapidly retreating glaciers, and produce a digital elevation models (DEMs) that approximates the mean elevation over the ICESat era (2003–2009)
We have presented three novel and complete high-resolution geographic data sets for the Greenland Ice Sheet designed to serve as benchmarks for change detection, control for image orthorectification and other topography or surface classification-dependent processing and constraints for ice sheet models
Summary
The objective of the Greenland Ice sheet Mapping Project (GIMP) is to establish benchmark data sets for observing ice sheet change. The drawbacks of automated, multispectral classification methods are that (1) they cannot differentiate between seasonal/ephemeral snow cover and glacial ice, (2) they fail at marine margins when dense packs of icebergs and sea ice are present, (3) much of the marginal ice of the Greenland Ice Sheet and surrounding glaciers is debris-covered and (4) Landsat does not cover the most northern regions of the ice sheet For these reasons, we abandoned multispectral mapping methods in favor of manual digitization of the panchromatic and pan-sharpened multispectral image mosaic presented in Sect. Rastner et al (2012) compared the version 1.1 GIMP classification to their own, semiautomated delineation of peripheral glaciers and ice caps, which utilized Landsat 7 data They found an overall difference in classified area of 6 %. Set and describe the procedure for merging them, followed by a description of errors and artifacts in the resulting DEM
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