Energy balance with very shallow snowpacks (<20cm)
The energy balance improved significantly with commit 571, 572 and 573. However, problems are still present in shallow snow covers (< ca. 20cm). I leave it here now, but as a hint for future development:
The problem is likely related with determining the soil heat flux in combination with penetrating short wave radiation which is absorbed in the top node of the soil. The latter might be considered an energy loss of the snowpack, as it is incoming energy at the surface which is transferred directly to the soil. However, it also influences the gradient in the upper soil layer and thereby the soil energy flux. It's not clear what is the best way to deal with this.