Snowfall fraction is an optional forcing data. It is used for separation of precipitation into snow and rain if snowfallmodel is set in info.txt, otherwise air temperature is used to determine the snowfall fraction. The file is located in the forcingdir folder. Snowfall fraction (unitless value 0-1) is given for all time steps. The SFobs-file is read only if readsfobs is set in info.txt.

The file may have comment rows in the beginning of the file. These rows have to begin with !!. The first row read is column headings. It holds a text string (e.g. 'date', no spaces allowed) for the first column, and integers in the form of station or subbasin ID numbers for the rest of the columns.

The first column is date-time. The default format is yyyy-mm-dd [HH:MM], where hour and minutes are necessary if the timestep is shorter than one day. The date-time is the beginning of the timestep. It is possible to use another date-time format: yyyymmdd[HHMM]. It is expected for all forcing files, if readformat 1 is set in info.txt.

The second to last columns are snowfall fraction for all stations or subbasins. The ID number (first row) may be sfobsid or subid. If sfobsid is used, several subbasins may use the same snowfall fraction time series. subid is defined in GeoData.txt. The order of subbasins in SFobs.txt does not have to be same as in GeoData.txt. sfobsid may be defined in ForcKey.txt.

Example snippet of SFobs.txt file:

date         1234  1245 
1990-01-01   1     1  
1990-01-02   0.85  1 
... 

SFobs_nnn.txt holds snowfall fraction forcing data for sequence with seqnr nnn. For seqnr 0 SFobs.txt is used.