 |
| Titel |
Seasonal changes of surface velocity and elevation of Columbia Glacier, Alaska using time-series TerraSAR-X/TanDEM-X data |
| VerfasserIn |
Saurabh Vijay, Matthias Braun |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250105445
|
| Publikation (Nr.) |
 EGU/EGU2015-4969.pdf |
|
|
|
|
|
| Zusammenfassung |
| Alaskan glaciers are a major contributor to global sea-level rise from
glaciers and ice caps outside the polar ice sheets. Columbia Glacier is a
large tidewater glacier located on the coast of south-central Alaska. The
glacier has retreated $\sim $ 21 km and lost half of its volume during
1957-2007, more rapidly after 1980. It is now split into two branches, known
as Main/East and West branch.
In this study, we used time series of high-resolution TerraSAR-X/TanDEM-X
stripmap satellite imagery during 2011-2014 to investigate the temporal
development of glacier surface velocities, elevation and mass changes. The
active SLC images of the bistatic TanDEM-X acquisitions, acquired over 11 or
22 days repeat intervals, are utilized to derive surface velocity fields
using SAR intensity offset tracking. We observed a very strong seasonal
variability in the surface velocities. Maximum values at the ice front reach
up to 14.43 m/day in May and reduced to 2 m/day in October in the year 2012.
However, at a distance of 17.5 km from the ice front, almost no seasonal
variability can be observed. A significant influence in the distance to the
terminus and elevation was detected. We attributed this temporal and spatial
variability of surface velocity to changes in the basal hydrology and
lubrification of the glacier bed. Similar fluctuations are observed in
consecutive years.
In a second step, we exploited TanDEM-X data by interferometrically
generating time series of digital elevation models (DEMs) . For quantitative
volume change estimates, we used DEMs of almost similar months of the
observational years in order to minimize errors resulting from variable
X-band radar penetration. The main branch gained a volume of
$\mbox{12.77}\pm \mbox{2.89}km^\mbox{3}$in 2011-12, but lost
$-\mbox{18.94}\pm \mbox{3.21}km^\mbox{3}$in 2012-13 . A slight gain was
observed with $\mbox{1.05}\pm \mbox{.88}km^\mbox{3}$in 2013-14. However, the
west branch gained volume only in 2011-12 and lost in the consecutive years.
Moreover, the west branch retreated by $\sim $ 3km and lost its area twice
faster than the main branch during 2011-14. |
|
|
|
|
|
|