1. Please write down the name (and abbreviation) of your snow model or land-surface model with snow component?

Melbourne University Snow Model (MU-SNW)

2. Name and address of model developer;

Associate Professor Ian Simmonds
Dr. David Walland
School of Earth Sciences
University of Melbourne
Parkville, Victoria
Australia, 3052

3. Name and address of model user;

Associate Professor Ian Simmonds
School of Earth Sciences
University of Melbourne
Parkville, Victoria
Australia, 3052

4. Please indicate whether your model is developed for application

   in understanding snow processes,     
   in a runoff forecasting model,       
   in a weather forecasting model,      X
   in a global climate model (GCM),     X
   or other (please specify)?                 

5. The first year when the model was used;


6. One paragraph description of your model (e.g. abstract from report or paper);

An interactive snow hydrology scheme suitable for incorporating into a general circulation model (GCM). The algorithm accounts for a prognostic calculation of snow depth and snow fraction and models the hydrological budget and energy balance over the snow surface. In addition, the scheme incorporates the effect of sub-grid-scale variations in topography with a novel statistical approach.

7. Please specify any known application range or restrictions;

8. What are the development data needs;

None at present.

9. What are the operational data needs?


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                  : X
   downwelling shortwave radiation : X
   downwelling longwave  radiation : X
   cloud cover                     : X
   surface pressure                : X

11. List the state variables (e.g., snow temperature, snow water equivalent, etc) your snow model uses?

Snow depth, snow fraction, snow temperature (single value)

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?

Roughness, albedo, heat capacity

13. What are the output data?

As 11.

14. What computer language does your model use?


15. How many subroutines (or functions) does your snow model have?

About 5

16. Number of lines of the snow code?

About 300

17. What is the recommended hardware?

Is very portable

18. How does your model determine the form of precipitation (i.e., snowfall and rainfall)? Please give the formulation.

Temperature at second bottom sigma level (0.929) greater or less than 0C.

19. Is your snow model one dimensional or multi-dimensional? Please specify.

One dimensional, but includes information about the sub grid scale topography.

20. If one dimensional, how many layers are there in your snow model? Please specify layering structure.

One layer

21. What is your snow model time step?

About 20 mins.

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

      snow age                 
      grain size                  
      solar zenith angle      
      snow depth?           
Albedo solely a function of latitude.

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?

Implicitly, yes. See treatment of ablating and non-ablating parts of the pack within each grid box. (P. 965 1996IJC, 961-982)

32. How is areal snow distribution treated?

See 31.

33. Does your snow model account for sub-grid (or sub-watershed) effects of topography? If so, how is temperature distributed?

Yes. Specified variables are considered as uniform across grid box. However, topographic variations are represented and allow seeding.

        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)? 
Snow fraction (for a given mean depth) is dependent on the
height of the (prescribed) 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?

Net albedo depends on snow fraction,(and hence see 35.)

39. In the presence of vegetation, how is snow surface roughness altered?

Wilson and Henderson-Sellers data.

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?

No runoff.

42. How is frozen soil treated in your model?

Not treated

43. Has your snow model been tested with the field data?

If so, what data? (areas)

what are their temporal and spatial scales?

NOAA/NESDIS satellite data

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?

Yes. NOAA/NESDIS satellite data.

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?

Plans are to parameterise the subgrid scale structure of precipitation, wind and possibly cloud.

50. Please provide references relevant to the model description and use.

Walland, D.J., and I. Simmonds, 1996: Sub-grid-scale topography and the simulation of Northern Hemisphere snow cover. International Journal of Climatology, 16, 961-982.

Walland, D.J., 1996: Snow and its role in climate and climate variability. Ph.D. thesis, School of Earth Sciences, The University of Melbourne, 293 pp.

Walland, D.J., and I. Simmonds, 1994: An interactive snow scheme for a General Circulation Model. Research Activities in Atmospheric and Oceanic Modelling, Report No. 19, WMO/TD-No. 592. G. J. Boer, Ed., World Meteorological Organization, 4.63-4.64.

Walland, D.J., and I. Simmonds, 1997: North American and Eurasian snow cover co-variability. Tellus, 49A, 503-512.

Walland, D.J., and I. Simmonds, 1997: Association between modes of variability of January Northern Hemisphere snow cover and circulation. Theoretical and Applied Climatology, 58, 197-210.

Walland, D.J., and I. Simmonds, 1997: Modelled atmospheric response to changes in Northern Hemisphere snow cover. Climate Dynamics, 13, 25-34.

-- Last updated Fri Oct 8 12:47:54 MST 1999 by Zong-Liang Yang.
For questions and comments, please contact Zong-Liang Yang