Abstract
We present in this paper a polynomial fitting method applicable to segments of footprints measured by the Geoscience Laser Altimeter System (GLAS) to estimate glacier thickness change. Our modification makes the method applicable to complex topography, such as a large mountain glacier. After a full analysis of the planar fitting method to characterize errors of estimates due to complex topography, we developed an improved fitting method by adjusting a binary polynomial surface to local topography. The improved method and the planar fitting method were tested on the accumulation areas of the Naimona’nyi glacier and Yanong glacier on along-track facets with lengths of 1000 m, 1500 m, 2000 m, and 2500 m, respectively. The results show that the improved method gives more reliable estimates of changes in elevation than planar fitting. The improved method was also tested on Guliya glacier with a large and relatively flat area and the Chasku Muba glacier with very complex topography. The results in these test sites demonstrate that the improved method can give estimates of glacier thickness change on glaciers with a large area and a complex topography. Additionally, the improved method based on GLAS Data and Shuttle Radar Topography Mission-Digital Elevation Model (SRTM-DEM) can give estimates of glacier thickness change from 2000 to 2008/2009, since it takes the 2000 SRTM-DEM as a reference, which is a longer period than 2004 to 2008/2009, when using the GLAS data only and the planar fitting method.
Highlights
Glacier thickness change is one of the most important observations to estimate glacier mass balance
In order to demonstrate the capability of the improved method to give more accurate estimates of glacier thickness change, the method of fitting a linear trend was used to calculate glacier thickness changes for Guliya and Chasku
For better measurement of the actual change in glacier surface elevation, and to reduce the influences of low Geoscience Laser Altimeter System (GLAS) data density, Shuttle Radar Topography Mission (SRTM) Digital Elevation Models (DEM) grid values were used as measurements in the year 2000 and each grid was taken as one footprint
Summary
Glacier thickness change is one of the most important observations to estimate glacier mass balance. Several methods have been applied to measure glacier thickness change: (1) in situ measurements; (2) difference of multi-temporal Digital Elevation Models (DEM) [2,3,4]; and (3) satellite radar altimetry [5]. Positioning System) or stakes to monitor glacier surface elevation changes, which is labor- and time-consuming. Differencing multi-temporal DEMs [3,4] have the advantage of capturing the spatial distribution of glacier thickness change. Background images images are are from Google Earth. 7. Glacier thickness change trends on glacier surface extremely complex topography. 7. Glacier thickness change trends on glacier surface withwith extremely complex topography as as shown in q: probability value.
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.
