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| Titel |
Recent changes in spring snowmelt timing in the Yukon River basin detected by passive microwave satellite data |
| VerfasserIn |
K. A. Semmens, J. M. Ramage |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 7, no. 3 ; Nr. 7, no. 3 (2013-06-05), S.905-916 |
| Datensatznummer |
250017974
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| Publikation (Nr.) |
 copernicus.org/tc-7-905-2013.pdf |
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| Zusammenfassung |
| Spring melt is a significant feature of high latitude snowmelt dominated
drainage basins influencing hydrological and ecological processes such as
snowmelt runoff and green-up. Melt duration, defined as the transition period
from snowmelt onset until the end of the melt refreeze, is characterized by
high diurnal amplitude variations (DAV) where the snowpack is melting during
the day and refreezing at night, after which the snowpack melts constantly
until depletion. Determining trends for this critical period is necessary for
understanding how the Arctic is changing with rising temperatures and
provides a baseline from which to assess future change. To study this dynamic
period, brightness temperature (Tb) data from the Special Sensor
Microwave Imager (SSM/I) 37 V-GHz frequency from 1988 to 2010 were used to
assess snowmelt timing trends for the Yukon River basin, Alaska/Canada.
Annual Tb and DAV for 1434 Equal-Area Scalable Earth (EASE)-Grid
pixels (25 km resolution) were processed to determine melt onset and melt
refreeze dates from Tb and DAV thresholds previously established
in the region. Temporal and spatial trends in the timing of melt onset and
melt refreeze, and the duration of melt were analyzed for the 13 sub-basins
of the Yukon River basin with three different time interval approaches.
Results show a lengthening of the melt period for the majority of the
sub-basins with a significant trend toward later end of melt refreeze after
which the snowpack melts day and night leading to snow clearance, peak
discharge, and green-up. Earlier melt onset trends were also found in the
higher elevations and northernmost sub-basins (Porcupine, Chandalar, and
Koyukuk rivers). Latitude and elevation displayed the dominant controls on
melt timing variability and spring solar flux was highly correlated with melt
timing in middle (∼600–1600 m) elevations. |
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