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| Titel |
Modelling ice layer formation using a preferential flow formulation in the physics based multi-layer SNOWPACK model |
| VerfasserIn |
Nander Wever, Sebastian Würzer, Charles Fierz, Michael Lehning |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250129298
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| Publikation (Nr.) |
 EGU/EGU2016-9389.pdf |
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| Zusammenfassung |
| For physics based snow cover models, simulating the formation of dense ice layers inside the
snowpack has been a long time challenge. In spite of their small vertical extend, the presence
of ice lenses inside the snowpack can have a profound impact on vapor, heat and liquid water
flow. These effects may ultimately influence processes on larger scales when, for example,
looking at hydrological processes or wet snow avalanche formation. Also microwave
emission signals from the snowpack are strongly influenced by the presence of ice layers.
Recent laboratory experiments and modelling techniques of liquid water flow in
snow have advanced the understanding of liquid water flow in snow, in particular
the formation of preferential flow paths. We present a modelling approach in the
one-dimensional, multi-layer snow cover model SNOWPACK for preferential flow
that is based on a dual-domain approach (i.e., separation into a matrix flow and
a preferential flow domain) and solving Richards equation for both. In recently
published laboratory experiments, water ponding inside the snowpack has been
identified to initiate preferential flow. Those studies also quantified the part of the
snowpack involved in preferential flow as a function of grain size. By combining
these concepts with an empirical function to determine refreezing of preferential
flow water inside the snowpack, we are able to simulate preferential water flow in
the model. We found that preferential flow paths arriving at a layer transition in
the snowpack may lead to ponding conditions. Subsequent refreezing then may
form dense ice layers (>700 kg/m3). We compare the simulations to 14 years of
biweekly snow profiles made at the Weissfluhjoch study plot at 2540m altitude in the
Eastern Swiss Alps. We show that we are able to reproduce several ice lenses that
were observed in the field, whereas some profiles remain challenging to simulate. |
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