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

Biosphere-Atmosphere Interaction Model (BAIM)

2. Name and address of model developer;

  Climate Research Department
  Meteorological Research Institute
  Nagamine 1-1, Tsukuba, Ibaraki 305, Japan
  phone: +81-298-53-8592
  fax  : +81-298-55-2552
  e-mail: kmabuchi@mri-jma.go.jp

3. Name and address of model user;

Meteorological Research Institute

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 (global or regional climate models)  
   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);

BAIM has two vegetation layers and three soil layers, and predicts the temperature of each layer and moisture stored for each layer. In the presence of snow on the ground, the snow layer is divided into a maximum of three layers, and the temperature and the amount of snow and water stored in each layer are predicted. BAIM can estimate not only the energy fluxes but also the carbon dioxide flux between the land surface ecosystem and the atmosphere. The photosynthesis processes for C3 plants and C4 plants are adopted in the model. BAIM can also predict the accumulation and melting of snow on the ground, and the freezing and melting of water in the soil.

7. Please specify any known application range or restrictions;

A model for use in physical climate models.

8. What are the development data needs;

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                  :   
   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 layer temperature,
      snow water equivalent,
      liquid water stored in the snow layer,
      snow density,
      surface snow albedo.

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?

     maximum and minimum of snow density,
     maximum and minimum of snow albedo,
     e-folding time of albedo and density change,
     specific heat of snow,
     maximum water saturation rate of snow layer,
     roughness of snow surface,
     density of ice,
     coefficient for estimation of heat conductivity of snow layer,
     depths of surface and bottom snow layers.

13. What are the output data?

     accumulation and melting rate of snow,
     sensible and latent heat fluxes between snow surface and atmosphere.

14. What computer language does your model use?


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

29 (total of all BAIM subroutines).

16. Number of lines of the snow code?

About 5000 lines (total of all BAIM subroutines).

17. What is the recommended hardware?

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

By air temperature.

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

One dimensional.

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

Divided into a maximum of three layers according to the amount of snow on the ground.

21. What is your snow model time step?

One hour (off-line) or less (in climate models).

22. Does your model snow albedo allow its

    spectral differences    (visible vs. near-IR)?   X
    directional differences (direct  vs. diffuse)? 

23. Is your model snow albedo a function of

      snow age                 X
      grain size                  
      solar zenith angle        
      snow depth?               

24. Does your snow model explicitly treat liquid water retention and percolation within the snowpack?

Liquid water retention is explicitly treated. Water in excess of the maximum value that snow layer can hold drains away and flows down to the soil surface without any time lag.

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?

Changing with time.

27. Is heat capacity and conductivity in your snow model changing with time or fixed?

Changing with time.

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),            X
 different vegetation heights   (short vs. tall),              X
 different vegetation densities (small vs. large LAI),         X
 different vegetation coverages (sparse vs. dense vegetation)? X

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?

According to LAI.

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)?

Drainage water generated by melting of snow in each snow layer flows down to the soil surface.

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

Melting water flows down to the soil surface infiltrate into soil. Flow down water in excess of the maximum hydraulic conductivity of soil treated as soil surface runoff.

42. How is frozen soil treated in your model?

Liquid water and ice in the soil layers are prognostic variables of BAIM.

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


If so, what data? (areas)

what are their temporal and spatial scales?

Snow data observed routinely at the observatory of Japan Meteorological Agency.

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?

Not yet.

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?

BAIM will be used in our new global and regional climate models.

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

Mabuchi,K.,Y.Sato,H.Kida,N.Saigusa and T.Oikawa,1997: A Biosphere-Atmosphere Interaction Model (BAIM) and its primary verifications using grassland data. Papers in Meteorology and Geophysics, Vol.47,No.3.

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