1. Please write down the name (and abbreviation) of your snow model or land-surface model with snow component?
2. Name and address of model developer;
Simon Hewitt Telephone(w): +61 3 9344 6339 Ph.D Student _--_|\ Telephone(h): +61 3 9877 2070 Department of Geography / \ Fax : +61 3 9344 4972 University of Melbourne \_.--._/ Parkville v Victoria 3052 AUSTRALIA E-mail: firstname.lastname@example.org
3. Name and address of model user;
4. Please indicate whether your model is developed for application
in understanding snow processes,
in a runoff forecasting model,
in a weather forecasting model,
in a global climate model (GCM),
or other (please specify)? X
Model developed to downscale GCM output to the local scale, with
further applications for climate change sensitvity evaluations.
Model is used for assessing snowpack fluctuations in the Australian Alps.
5. The first year when the model was used;
6. One paragraph description of your model (e.g. abstract from report or paper);
The model uses daily-scale synoptic data to estimate the daily fluctuations (accumulation/ablation) at the Falls Creek site in the Australian Alps (elev. 1649 m). The model consists of a statistical reegression relationship between daily snowpack changes and a set of predictor variables. These include the 500 hPa temperature, water vapour mixing ratio at 1000 hPa, airstream speed at 100 hPa and 500 hPa and the wind direction at 500 hPa. These variables are sampled along a transect south of the model site, in the Bass Strait between Victoria and Tasmania.
7. Please specify any known application range or restrictions;
Large-scale driving atmospheric inputs (e.g. GCM) needs to replicate the observed climate with reasonable precision. Model has difficulty simulating the very high daily variability evident in observed data.
8. What are the development data needs;
High quality obs for both daily snow data and atmospheric data over study region.
9. What are the operational data needs?
10. Please indicate with an "x" for those meteorological variables used to
DRIVE your snow model?
air temperature : X
wind speed : X
wind direction : X
downwelling shortwave radiation : X
downwelling longwave radiation :
cloud cover :
surface pressure :
11. List the state variables (e.g., snow temperature, snow water equivalent, etc) your snow model uses?
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?
Daily changes in snowpack depth (not water equiv.) at model site (in cm)
14. What computer language does your model use?
Statistical regression model run on Excel spreadsheet
15. How many subroutines (or functions) does your snow model have?
Three regression equations to account for seasonailty.
16. Number of lines of the snow code?
17. What is the recommended hardware?
Any system with reasonable processing speed for dearchiving obs data, and deriving regression equations
18. How does your model determine the form of precipitation (i.e., snowfall and rainfall)? Please give the formulation.
Determined with regression equations.
19. Is your snow model one dimensional or multi-dimensional? Please specify.
20. If one dimensional, how many layers are there in your snow model? Please specify layering structure.
21. What is your snow model time step?
22. Does your model snow albedo allow its
spectral differences (visible vs. near-IR)?
directional differences (direct vs. diffuse)?
23. Is your model snow albedo a function of
solar zenith angle
24. Does your snow model explicitly treat liquid water retention and percolation within the snowpack?
25. Does your snow model account for changes in the hydraulic and thermal properties of snow due to meltwater refreezing?
26. Is snow density in your snow model changing with time or fixed?
27. Is heat capacity and conductivity in your snow model changing with time or fixed?
28. Does your snow model simulate vapor transfer in the snowpack?
29. Does your snow model account for the heat transfer between the bottom of the snowpack and the underlying soil?
30. In snow energy balance, does your model consider heat convected by rain or falling snow?
31. Does your snow model include snow drifting and redistribution by wind (or avalanche)? If so, how?
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?
34. Does your snow model consider snow-vegetation interaction?
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)?
(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?
If so, what data? (areas)
what are their temporal and spatial scales?
Yes - calbrated using around 1000 days of observed data, and then validated using a further 300 days of obs not used in the calibration process. Fixed spatial scale, daily temporal scale.
44. Has your snow model been used together with remote sensing data as input?
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?
No - difficulty with satellite remote sensing of Australian snow due to relatively small spatial coverage (<11 000 square km)
46. Please list any other previous applications.
Some use in assessing runoff volume and seasonality for hydr-electricity and irrigation purposes.
47. Please specify verification criteria, if any?
Validation simulation, as noted above.
48. What are the model fitting procedures, if any?
49. What are future plans for using/improving the model?
Smaller scale atmospheric data will improve model performance, and possible use with NWP and higher resolution GCM data for both operational forecasting and climate studies.
50. Please provide references relevant to the model description and use.
Hewitt, S. D., Finlayson, B. L., McMahon, T. A and Simmonds, I. 1997. Assessing the sensitivity of Australian alpine snow cover to enhanced- greenhouse climate change (in preparation).