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| Titel |
LiDAR measurement of seasonal snow accumulation along an elevation gradient in the southern Sierra Nevada, California |
| VerfasserIn |
P. B. Kirchner, R. C. Bales, N. P. Molotch, J. Flanagan, Q. Guo |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 18, no. 10 ; Nr. 18, no. 10 (2014-10-30), S.4261-4275 |
| Datensatznummer |
250120508
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| Publikation (Nr.) |
 copernicus.org/hess-18-4261-2014.pdf |
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| Zusammenfassung |
| We present results from snow-on and snow-off airborne-scanning LiDAR
measurements over a 53 km2 area in the southern Sierra Nevada. We found
that snow depth as a function of elevation increased approximately 15 cm per
100 m, until reaching an elevation of 3300 m, where depth sharply decreased
at a rate of 48 cm per 100 m. Departures from the 15 cm per 100 m trend,
based on 1 m elevation-band means of regression residuals, showed slightly
less steep increases below 2050 m; steeper increases between 2050 and
3300 m; and less steep increases above 3300 m. Although the study area is
partly forested, only measurements in open areas were used. Below
approximately 2050 m elevation, ablation and rainfall are the primary causes
of departure from the orographic trend. From 2050 to 3300 m, greater snow
depths than predicted were found on the steeper terrain of the northwest and
the less steep northeast-facing slopes, suggesting that ablation, aspect,
slope and wind redistribution all play a role in local snow-depth
variability. At elevations above 3300 m, orographic processes mask the
effect of wind deposition when averaging over large areas. Also, terrain in
this basin becomes less steep above 3300 m. This suggests a reduction in
precipitation from upslope lifting and/or the exhaustion of precipitable
water from ascending air masses. Our results suggest a cumulative
precipitation lapse rate for the 2100–3300 m range of about 6 cm per
100 m elevation for the accumulation period of
3 December 2009 to 23 March
2010. This is a higher gradient than the widely used PRISM
(Parameter-elevation Relationships on Independent Slopes Model) precipitation
products, but similar to that from reconstruction of snowmelt amounts from
satellite snow-cover data. Our findings provide a unique characterization of
the consistent, steep average increase in precipitation with elevation in
snow-dominated terrain, using high-resolution, highly accurate data and
highlighs the importance of solar radiation, wind redistribution and
mid-winter melt with regard to snow distribution. |
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