Snow modelling using Surfex with the Crocus snow

Snow modelling using Surfex with the Crocus snow scheme for Norway Dagrun Vikhamar-Schuler 1 and Karsten Müller 2 1 MET. NO , 2 NVE

Weather forecasts Data sources Weather stations se. Norge. no Physical snow models Gridded 1 km maps: snow depth, temp, prec. Snow observations

CROCUS snow scheme: - Up to 50 layers - Temp - Grain size, type - Liquid Water cont. - Density -. . Snow depth SURFEX: land-surface model from HARMONIE atm. model. Snow temperature Date Ref: Eric Brun and Samuel Morin, Meteo. France

1 D model run for weather stations in Norway

Driving data? Short- and longwave radiation Precipitation (+prec. phase) Air temperature Wind dir. + speed Surface pressure Air humidity Too few parameters are observed at the weather stations to drive SURFEX. Can forecasts replace observations without reducing the quality of the modeled snow depth?

Grotli (872 masl): 2009 -2010 - forcing data: observations except …: UM: Radiation, Surface pressure UM: Radiation, Air humidity UM: Radiation, Temperature Observed Snow Depth Modelled Snow Depth UM: Radiation, Wind UM: Radiation, Precipitation

Sensitivity study Ø For all Stations (Grotli, Filefjell, Beitostølen, Mannen, NGIfonnbu): Ø BEST results using OBSERVATIONS precipitation and temperature. of Ø Other parameters seems ok to derive from Met. UM (NWP) forecasts.

We have evaluated the snow depth. What about the snow pack layers?

Filefjell winter 2011 -2012 Snow density(kg/m 3) 1 Sept 2011 17 April 2012 Liquid water content (%

Snow Temperatures FILEFJELL Weather Station Ø Snow temperatures are measured hourly Ø 0, 5, 15, 30 og 55 cm snow height ºC Ground surface temperature 2010 2011

Summary CROCUS reproduces well the observed snow depth using observations. Ø Results are most sensitive to precipitation and temperature Ø l Ø Ongoing work: comparing driving data: l l Ø Other parameters ok to derive from NWP data NWP models (Harmonie 2. 5 km) Observations Future: 2 D simulations