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| Titel |
Modelled sensitivity of the snow regime to topography, shrub fraction and shrub height |
| VerfasserIn |
C. B. Ménard, R. Essery, J. Pomeroy |
| 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. 6 ; Nr. 18, no. 6 (2014-06-26), S.2375-2392 |
| Datensatznummer |
250120395
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| Publikation (Nr.) |
 copernicus.org/hess-18-2375-2014.pdf |
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| Zusammenfassung |
| Recent studies show that shrubs are colonizing higher latitudes and altitudes
in the Arctic. Shrubs affect the wind transport, accumulation and melt of
snow, but there have been few sensitivity studies of how shrub expansion
might affect snowmelt rates and timing. Here, a three-source energy balance model
(3SOM), which calculates vertical and horizontal energy fluxes – thus
allowing within-cell advection – between the atmosphere, snow, snow-free
ground and vegetation, is introduced. The three-source structure was specifically
adopted to investigate shrub–tundra processes associated with patchy
snow cover that single- or two-source models fail to address. The ability of
the model to simulate the snow regime of an upland tundra valley is
evaluated; a blowing snow transport and sublimation model is used to simulate
premelt snow distributions and 3SOM is used to simulate melt. Some success at
simulating turbulent fluxes in point simulations and broad spatial pattern in
distributed runs is shown even if the lack of advection between cells causes
melt rates to be underestimated. The models are then used to investigate the
sensitivity of the snow regime in the valley to varying shrub cover and
topography. Results show that, for domain average shrub fractional cover
≤0.4, topography dominates the pre- and early melt energy budget but
has little influence for higher shrub cover. The increase in domain average
sensible heat fluxes and net radiation with increasing shrub cover is more
marked without topography where shrubs introduce wind-induced spatial
variability of snow and snow-free patches. As snowmelt evolves, differences
in the energy budget between simulations with and without topography remain
relatively constant and are independent of shrub cover. These results suggest
that, to avoid overestimating the effect of shrub expansion on the energy
budget of the Arctic, future large-scale investigations should consider wind
redistribution of snow, shrub bending and emergence, and sub-grid topography
as they affect the variability of snow cover. |
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