Snow accumulation and snow melt

Solid precipitation accumulates in the interception storage and at the land surface if air temperatures are below 0 °C. Snow melt occurs for air temperatures above 0 °C and is based on degree-day approach. Snow melt runoff is initiated if liquid storage of the snow cover (\(S_{snow-l}`\)) exceeds the retention capacity of the snow cover \(S_{snow-ret}\) (mm):

\[S_{snow-ret}=\frac{10000}{\frac{100-r_{max}}{100}} \cdot swe\]

where \(r_{max}\) is the retention factor of the snow cover (%) and \(swe\) is the snow water equivalent of the snow cover (mm).

Snow melt \(q_{snow}\) (mm) is calculated as:

\[q_{snow}=s_f \cdot (TA-TA_m) \cdot \Delta t\]

where \(s_f\) is the degree-day factor (mm °:math:C^{-1} \(h^{-1}\)), \(TA\) is the air temperature (°C), \(TA_m\) is equal to 0 °C and \(\Delta t\) is time step (h).