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

SPONSOR (land-surface model)

2. Name and address of model developer;

Andrey B.Shmakin,
Institute of Geography,
Russian Academy of Sciences,
Staromonetny St., 29,
Moscow 109017, Russia
E-mail: climat@ipcom.ru

3. Name and address of model user;

as above

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)?           X (regional climate model)

5. The first year when the model was used;

1997 (the snow block of the model).

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

The model deals with all main processes which occur in the snow cover and freezing soil. In the beginning of the cold season these processes include accumulation of snow at the surface; coverage of vegetation by snow with corresponding changes of albedo and aerodynamic roughness; cooling of thin upper soil layer below 0^C due to the energy exchange at the surface; moving of the frosen zone into the soil considering the external cooling and heat flux from the deeper layers; freezing of the soil water keeping the zero temperature near the freezing front; upward flux of liquid water to the front with its freezing.

The main processes of the melting period are: snow melting (due to heat income with rain or warm fog, or excess of energy income at upper or lower boundary) with secondary refreezing of melt water in the snow cover; melting of the upper soil layer due to the excess of available heat; melt water infiltration into the frozen layers with partial refreezing.

Except for meteorological parameters need for the model as forcing, one needs the ground temperature at a depth lower than the soil layer (for example, 3 m) once a week or a month. If the water table is located closely enough to the lower soil boundary, its depth must be specified too. In this case the water table provides additional water influx to the soil where the water can freeze.

7. Please specify any known application range or restrictions;

The model can be used for rather large spatial scale evaluations, as within an atmospheric model as an independent tool. The size of the grid cells must be no less than several dozens of kilometers as some local mechanisms are not considered in the model. The temporal resolution is about 0.5 - 1 hour, while for the snow block it can be taken as several minutes. The time step cannot be larger than 1 day because of typical time scale of the processes within snow cover and frozen soil. The scheme doesn't account for some specific cases (for example, snow on the ice covering a waterbody or on a glacier), while it can be used for wide range of landscapes in any geographical zone, including highlands and mountains.

8. What are the development data needs;

The model needs several parameters describing land cover type. They must be defined either directly or from typical values for the given land cover type if the latter is known. The necessary data set includes LAI, SAI (the same as LAI for non-green parts of vegetation), vegetation height, vegetation albedo, fraction of the landscape covered by vegetation, relative fraction of roots in each soil layer, depth of the root zone, minimum aerodynamic roughness length and zero plane displacement of the landscape, thermal emissivity of the landscape, soil hydraulic conductivity at saturation, soil porosity, soil field capacity, wilting point, soil matrix potential at saturation, Clapp-Hornberger "b" parameter, bare soil albedo, dry soil thermal conductivity and heat capacity, ground temperature at a depth lower than modeled soil layer and water table depth (if less than soil bottom plus 2 meters) with monthly or less temporal resolution, dry soil density, ice heat capacity and thermal conductivity, fresh snow density, fresh snow thermal conductivity, 3 parameters of relief dissection at the scale of elementary streams, height of meteorological measurements (may be different for wind velocity and air temperature). If the radiation fluxes will be calculated within the model, the latitude and air transmissivity are necessary.

Initial data includes snow water equivalent, snow density, snow surface temperature, liquid water content within the snow cover, soil surface temperature, soil temperature at all calculation levels, soil water content (both liquid and frozen) for each layer, amount of intercepted precipitation.

9. What are the operational data needs?

see 10).

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                     : 
    (may be used for parameterization of both
     radiation fluxes if they are unavailable)
    (this variant is less accurate)
   surface pressure                : X 

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

snow surface temperature, 
snow temperature at the soil surface, 
snow water equivalent, 
liquid water content within the snow cover, 
snow density, 
snow intercepted by vegetation.

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?

Snow surface aerodynamic roughness, 
maximum albedo at visible wavelength,
density of fresh snow, 
speed of snow density growth according to its age,
snow heat capacity at 273.16K, 
snow thermal conductivity at 273.16K.

13. What are the output data?

Snow water equivalent, 
snow depth, 
sensible and latent heat fluxes, 
snow melting intensity, 
liquid water content within snow cover, 
absorbed solar radiation, 
snow intercepted by vegetation.

14. What computer language does your model use?


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

4 subroutines for the snow block only and 3 subroutines dealing with the snow characteristics.

16. Number of lines of the snow code?

About 400-450 (some operators deal not only with snow)

17. What is the recommended hardware?

No specific recommendations.

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

Snowfall if the air temperature is less than 273.16K, otherwise rainfall.

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.

2 (at both boundaries of snow cover)

21. What is your snow model time step?

30 to 60 minutes.

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?              X

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?

Thermal properties are changing according to the snow density transformations.

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?

The heat convected by liquid rain is considered; the heat brought by snowfall is not accounted.

31. Does your snow model include snow drifting and redistribution by wind (or avalanche)? If so, how?


32. How is areal snow distribution treated?

Not considered.

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?

The extent of coverage of vegetation by snow, with corresponding changes of aerodynamic parameters and albedo is considered.

35. Does the snow-vegetation interaction account for

 different vegetation types     (grass vs. forest), 
 different vegetation heights   (short vs. tall),          X
 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?

Yes, except for melting (snow is suggested to fall down from the vegetation if the air temperature is higher than 273.16K).

37. How is the upper limit of the canopy interception determined?

The same as for rain - 0.1(LAI+SAI).

38. In the presence of vegetation, how is snow surface albedo altered?

If the height of vegetation is larger than snow depth, surface albedo accounts for the snow amount, albedo of fresh snow and albedo of landscape without snow.

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

In spite of vegetation presence, the roughness length is taken as for the snow cover without vegetation; zero plane displacement is set to zero.

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)?

Affecting soil moisture and/or ice layer depth at the soil surface.

(b). Once snowmelt is generated, how does your model relate it to runoff?

In dependance on content of frozen and liquid soil water and/or ice layer depth at the soil surface.

42. How is frozen soil treated in your model?

According to the heat balance at each soil level; some amount of soil water cannot freeze at any negative temperature. Thermal properties of the soil are considered according to its humidity, porosity, etc. Lower boundary condition is the climatic soil temperature deeper than 3 m (varying by months if necessary).

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


If so, what data? (areas)

The data of Russian water balance stations located in different geographical zones, from steppes to permafrost areas.

what are their temporal and spatial scales?

Snow and frozen soil characteristics are given for each day (in some periods for each 3 hours) during several years (up to decades), for several points within the station watershed (usually several km^2).

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?

46. Please list any other previous applications.

there were no previous applications since the scheme is just created.

47. Please specify verification criteria, if any?

Accuracy of the estimation of periods of snow cover existence and of frozen soil must be within 1-2 days. The accuracy of intensity of snow melting and snow evaporation must be within 0.1 mm per day. The heat and water balances are checked according to usual PILPS requirements.

48. What are the model fitting procedures, if any?

Some adjustable parameters (soil and snow heat conductivities, maximum snow albedo, etc.) as well as some coefficients in equations can be changed in some extent.

49. What are future plans for using/improving the model?

Some particular blocks will be improved (influence of intercepted snow onto surface albedo, snow interception capacity according to the type of vegetation, turbulent fluxes at snow surface in the presence of vegetation above snow, snow albedo as function of snow age, etc.). The scheme is planned to be used in several GCMs and one regional climate model nested to GCM.

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

Shmakin, A.B., 1998: The updated version of SPONSOR land surface scheme: PILPS-influenced improvements. Global and Planetary Change, 19(1-4), 49-62.

Shmakin, A.B., 1999: Testing of cryologic landsurface parameterization scheme for seasonally frozen ground and seasonally melt permafrost. Preprints, 14th Conference on Hydrology, 10-15 January 1999, Dallas, TX, pp., 425-426.

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