New snow occurs in each time step is calculated using:
SNOWE = the solid water content of new snow, i.e. snow water equivalent (mm),
P = the precipitation in the time step (mm);
= the snow fall temperature which is usually assumed to be same as the snowmelt temperature.
The new snow is added to the solid water content in the snow pack.
SDEP = the snowpack depth (mm),
SWC = the solid (ice) water content (mm), the subscripts o and f denote the initial and final values of certain quantities (e.g. SWC) at the time of the calculation,
SNOW = the depth of new snowfall calculated using:
SNOW = SNOWE / NEWDEN
where NEWDEN is the relative density of new snow (vol/vol) with default value of 0.1 and range from 0.02 to 0.15.
As a result of any new snowfall, the relative dry density of the pack, RHO (vol/vol) is recalculated using:
RHO = SWC / SDEP
And the porosity, POR (vol/vol) is computed from:
POR = 1 – RHO / RHOICE
where RHOICE is the relative density of ice, usually taken as 0.92.