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Experiments on COSMO snow parameterization. J. Helmert, E. Machulskaya, B. Ritter with support of H. Ruppert, J. Förstner, Th. Hanisch. Background. COSMO experiments motivated from GME changes on - snow albedo - snow cover fraction - snow albedo evolution

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Experiments on cosmo snow parameterization
Experiments on COSMOsnow parameterization

J. Helmert, E. Machulskaya, B. Ritter

with support of

H. Ruppert, J. Förstner, Th. Hanisch


Experiments on cosmo snow parameterization

Background

COSMO experiments motivated from GME changes on

- snow albedo

- snow cover fraction

- snow albedo evolution

Aim: consistent physics in NWP models

decrease of cold bias in T_2M during winter

COSMO experiments:

8050: 18.12.2010 – 02.03.2011 snow fraction

8232: 18.02.2011 – 17.04.2011 snow albedo evolution

8233: 18.02.2011 – 17.04.2011 snow albedo evolution +

snow fraction


Experiments on cosmo snow parameterization

Snow albedo

Csalb_snow_min = 0.4000.500 ! snow for forest free surfaces

Csalb_snow_max = 0.7000.850 ! snow for forest free surfaces

Csalb_snow_fe = 0.2000.270 ! snow with evergreen forest

Csalb_snow_fd = 0.2000.320 ! snow with deciduous forest

Dutra et al., 2010


Snow aging
Snow aging

Temporal evolution ofsnow albedo

New approach

Aging function S


Experiments on cosmo snow parameterization

Snow fraction

Wcr = 15mm

ROUTI

Hcr = 0.1m

EXP

Dutra et al., 2010






Experiments on cosmo snow parameterization

SYNOP VERIF EXP 8050 vs ROUTI

18.12.10-30.01.11, 00 UTC

BIAS

T2M

TD2MD

TMIN

TMAX

PS

DD

FF

VW

RMSE

T2M

TD2MD

TMIN

TMAX

PS

DD

FF

VW


Experiments on cosmo snow parameterization

SYNOP VERIF EXP 8050 vs ROUTI

31.01.11-28.02.11, 00 UTC

BIAS

T2M

TD2MD

TMIN

TMAX

PS

DD

FF

VW

RMSE

T2M

TD2MD

TMIN

TMAX

PS

DD

FF

VW







Experiments on cosmo snow parameterization

SYNOP VERIF EXP 8032 vs ROUTI

18.03.11-17.04.11, 00 UTC

BIAS

T2M

TD2MD

TMIN

TMAX

PS

DD

FF

VW

RMSE

T2M

TD2MD

TMIN

TMAX

PS

DD

FF

VW


Experiments on cosmo snow parameterization

SYNOP VERIF EXP 8033 vs ROUTI

18.03.11-17.04.11, 00 UTC

BIAS

T2M

TD2MD

TMIN

TMAX

PS

DD

FF

VW

RMSE

T2M

TD2MD

TMIN

TMAX

PS

DD

FF

VW


Experiments on cosmo snow parameterization

Summary

  • COSMO experiments showed the expected impact of snow

  • parameterization changes on total albedo and T_2M

  • Parameterization changes are independent of used snow

  • model (single layer, multilayer)

  • Results should be used also in future COSMO with TILE

  • Further routine accompanying experiments (single layer,

  • multi layer) intended for autum 2011

  • Aim: Routine change in Spring 2012


Experiments on cosmo snow parameterization

SYNOP VERIF EXP 8050 vs ROUTI

RANGE 1, 12 UTC, BIAS


Experiments on cosmo snow parameterization

SYNOP VERIF EXP 8050 vs ROUTI

RANGE 1, 12 UTC, RMSE


Experiments on cosmo snow parameterization

SYNOP VERIF EXP 8050 vs ROUTI

RANGE 2, 12 UTC, BIAS


Experiments on cosmo snow parameterization

SYNOP VERIF EXP 8050 vs ROUTI

RANGE 2, 12 UTC, RMSE