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

MRI-CGCM ground hydrology model

2. Name and address of model developer;

 Y. Nikaidou
Present affiliation: Japan Meteorologial Agency
1-3-4, Ohtemachi, Chiyoda-ku, Tokyo 100, JAPAN

Response by
*   Dr. Akira Noda                        *
*   Climate Research Department           *
*   Meteorological Research Institute     *
*   Nagamine 1-1, Tsukuba, Ibaraki 305    *
*   JAPAN                                 *
*   e-mail: noda@mri-jma.go.jp            *
*   FAX:   +81-298-55-2552                *
*   phone: +81-298-53-8608                *

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),     X
   or other (please specify)?           X      
Developed for use in global climate research and global warming

5. The first year when the model was used;


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

Snow mass(snow water equivalent) on the ground is a prognostic variable. The model predicts the surface temperature of sea ice, glacier ice ( ice sheet), land or snow. Also, ground temperature, ground wetness, ground ice are predicted in the model.

7. Please specify any known application range or restrictions;


8. What are the development data needs;

Global data of snow depth and density

9. What are the operational data needs?

No 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                  :  
   humidity                        : X
   downwelling shortwave radiation : X
   downwelling longwave  radiation : X
   cloud cover                     : 
   surface pressure                : X

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

Snow surface temperature, snow mass, soil temperature, soil moisture and
soil ices.

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?

Surface roughness and mean albedo of (dry or wet) snow

13. What are the output data?

Same as #11

14. What computer language does your model use?

Fortran 77

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


16. Number of lines of the snow code?


17. What is the recommended hardware?

(super computer; Hitachi s-3800)

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

(Ts: surface air temperature,  Ti: freezing poinit temperature,)

 When Ts>Ti, rainfall occures.  The other case, snow falls

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.

Snow cover has one layer, and soil has 4 layers.

21. What is your snow model time step?

1 hour

22. Does your model snow albedo allow its

    spectral differences    (visible vs. near-IR)?  
    directional differences (direct  vs. diffuse)? 
No, it does not allow spectral differences but it does directional differences 
for the direct component.

23. Is your model snow albedo a function of

      snow age                 
      grain size                  
      solar zenith angle      
      snow depth?           
Dry snow albedo is calculated as Min(0.85,  0.7+0.15h), where h is height
in km. When snow melting occures, snow albedo is changed to 0.5.

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?

They are fixed in snow layer. But in soil layers, they are changed

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?

Do not consider areal distribution. Snow coverage fraction in a grid area is 1 or 0.

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

No, sub-grid effects are not accounted.

        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?

No canopy interception is considered.

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

No change

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

No change

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)?

Melt water percolates into the uppermost soil layer.

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

When soil is saturated, melting water becomes runoff

42. How is frozen soil treated in your model?

If soil temperature in a soil layer becomes lower than freezing point, phase change of soil wetness in the layer is calculated in consideration of thermodynamics.

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

If so, what data? (areas)

what are their temporal and spatial scales?

NESDIS snow cover data. Weekly and monthly

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. NESDIS snow cover 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?

More realistic snow model, including time evolution of snow density, particle diameter, albedo, viscosity, permeability, conductivity, and heat capacity

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

Phillips, T.J., 1994: A summary documentation of the AMIP models. PCMDI Report No.18, 180-189.

Kitoh, A., A. Noda, Y. Nikaidou, T. Ose and T. Tokioka, 1995: AMIP simulations of the MRI GCM. Pap. Meteor. Geophys., 45, 121-148.

Tokioka, T., A. Noda, A. Kitoh, Y. Nikaidou, S. Nakagawa, T. Motoi, S. Yukimoto and K. Takata, 1995: A transient CO2 experiment with the MRI CGCM --Quick Report--. J. Meteorl. Soc. Japan, 73, 817-826.

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