1. Please write down the name (and abbreviation) of your snow model or land-surface model with snow component?
SNOWPACK
2. Name and address of model developer;
Michael Lehning and Perry Bartelt, Swiss Federal Institute for Snow and Avalanche Research, Flueelastr. 11 Tel.: ++ 41 81 417 01 58 CH - 7260 Davos-Dorf Fax : ++ 41 81 417 01 10 mail: lehning@slf.ch
3. Name and address of model user;
As above
4. Please indicate whether your model is developed for application
in understanding snow processes, X
in a runoff forecasting model, (X)
in a weather forecasting model,
in a global climate model (GCM),
or other (please specify)? X
avalanche warning
5. The first year when the model was used;
1998
6. One paragraph description of your model (e.g. abstract from report or paper);
SNOWPACK is a one-dimensional snowcover model that is based on finite-element numerics and is used operationally by the Swiss Federal Insititute for Snow and Avalanche Research. It runs on the input data from approximately 50 automatic weather and snow stations in the Swiss Alps. One important characteristics is that the amount of new snow is determined from the measured total snow depth and the model-calculated settling rate together with an estimation of the new snow density. For the energy balance, Dirichlet and Neumann boundary conditions can be used. Using an improved formulation for snow metamorphism and linking the snow metamorphic rate to the viscosity and thermal conductivity, the mass and energy balance of the model compares well with independent measurements. It is shown that the model can be used to determine high Alpine snow precipitation rates. These estimations are more accurate than standard precipitation gauge measurements. Since in addition the ablation period in spring is modeled correctly, the model appears to be an appropriate tool for hydrologic applications in high Alpine environments. [from Lehning, M., P. Bartelt and R.L. Brown, 1998: The mass and energy balance of the SNOWPACK model, EOS, Transactions, American Geophysical Union, Fall Meeting, Supplement, Vol. 79, No. 45, page F272.]
7. Please specify any known application range or restrictions;
8. What are the development data needs;
9. What are the operational data needs?
Shortwave Radiation Air Temperature Snow depth or precipitation rates Rel. humidity Wind speed Surface temperature, longwave radiation or cloudiness Ground heat flux or ground temperature
10. Please indicate with an "x" for those meteorological variables used to
DRIVE your snow model?
precipitation : X
air temperature : X
wind speed : X
wind direction :
humidity : X
downwelling shortwave radiation : X
downwelling longwave radiation : X
cloud cover :
surface pressure :
11. List the state variables (e.g., snow temperature, snow water equivalent, etc) your snow model uses?
temperature, volume fractions of ice, water and air (density), grain radius, bond radius, sphericity, dendricity
12. List the measurable/adjustable parameters (e.g., snow surface aerodynamic roughness, maximum albedo at visible wavelength, etc, excluding initial conditions) your snow model uses?
13. What are the output data?
Variable, but all state parameters, a grain type code, amounts of new snow, meltwater production, albedo, surface hoar index
14. What computer language does your model use?
C
15. How many subroutines (or functions) does your snow model have?
Many
16. Number of lines of the snow code?
approx. 20000 including comments
17. What is the recommended hardware?
UNIX/PC
18. How does your model determine the form of precipitation (i.e., snowfall and rainfall)? Please give the formulation.
All precipitation is as snow at present, rain will be implemented
19. Is your snow model one dimensional or multi-dimensional? Please specify.
Operational 1D version and research 2D Version
20. If one dimensional, how many layers are there in your snow model? Please specify layering structure.
Finite Element layers, with each snowfall new layers/elements are added
21. What is your snow model time step?
Typically 15 minutes
22. Does your model snow albedo allow its
spectral differences (visible vs. near-IR)? No
directional differences (direct vs. diffuse)? No
23. Is your model snow albedo a function of
snow age X
grain size X
solar zenith angle
pollution
snow depth?
shortwave out X
snow surface temperature X
24. Does your snow model explicitly treat liquid water retention and percolation within the snowpack?
Yes, using a simple threshold approach
25. Does your snow model account for changes in the hydraulic and thermal properties of snow due to meltwater refreezing?
Yes
26. Is snow density in your snow model changing with time or fixed?
Changing
27. Is heat capacity and conductivity in your snow model changing with time or fixed?
Changing
28. Does your snow model simulate vapor transfer in the snowpack?
Not explicitely, but implicitely using ET and TG metamorphism
29. Does your snow model account for the heat transfer between the bottom of the snowpack and the underlying soil?
Yes
30. In snow energy balance, does your model consider heat convected by rain or falling snow?
Implicitely using an initial snow temperature, No rain at present
31. Does your snow model include snow drifting and redistribution by wind (or avalanche)? If so, how?
Will be implemented later
32. How is areal snow distribution treated?
-
33. Does your snow model account for sub-grid (or sub-watershed) effects of topography? If so, how is temperature distributed?
how is precipitation (spatial, elevation and corrections) distributed?
how is solar radiation distributed?
how is wind distributed?
how are other meteorological variables distributed?
Model uses point input parameters from measurements or external models
34. Does your snow model consider snow-vegetation interaction?
Not at present.
35. Does the snow-vegetation interaction account for
different vegetation types (grass vs. forest),
different vegetation heights (short vs. tall),
different vegetation densities (small vs. large LAI),
different vegetation coverages (sparse vs. dense vegetation)?
36. Are snow interception, drip and melt on canopy surface allowed in your model?
37. How is the upper limit of the canopy interception determined?
38. In the presence of vegetation, how is snow surface albedo altered?
39. In the presence of vegetation, how is snow surface roughness altered?
40. In the presence of forest, does your snow model allow spatial variability of snow depth and water equivalent on forest floor?
41(a). How does your model deliver snowmelt to the soil system (e.g. affecting soil moisture)?
Assumes that meltwater is taken up by the soil, no treatment of the soil
(b). Once snowmelt is generated, how does your model relate it to runoff?
42. How is frozen soil treated in your model?
43. Has your snow model been tested with the field data?
Yes.
If so, what data? (areas) Weissfluhjoch, Swizerland
what are their temporal and spatial scales?
Hourly, One point
44. Has your snow model been used together with remote sensing data as input?
No.
If so, how?
45. If your snow model is coupled with a numerical weather forecasting model or climate model, has the model snow product been compared with satellite data? If so, what satellite data were used?
46. Please list any other previous applications.
47. Please specify verification criteria, if any?
48. What are the model fitting procedures, if any?
49. What are future plans for using/improving the model?
Development and improvement of metamorphism, rain, coupling to weather forecast model, wind transport
50. Please provide references relevant to the model description and use.
Lehning et al., 1998: A network of automatic weather and snow stations and supplementary model calculations providing SNOWPACK information for avalanche warning, ISSW 98 International Snow Science Workshop, Sunriver, Oregon.
Lehning, M., P. Bartelt and R.L. Brown, 1998: The mass and energy balance of the SNOWPACK model, EOS, Transactions, American Geophysical Union, Fall Meeting, Supplement, Vol. 79, No. 45, page F272.