experiments on cosmo snow parameterization
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
Experiments on COSMOsnow 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
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 fraction8232: 18.02.2011 – 17.04.2011 snow albedo evolution8233: 18.02.2011 – 17.04.2011 snow albedo evolution + snow fraction
Csalb_snow_min = 0.400 0.500 ! snow for forest free surfaces Csalb_snow_max = 0.700 0.850 ! snow for forest free surfaces Csalb_snow_fe = 0.200 0.270 ! snow with evergreen forest Csalb_snow_fd = 0.200 0.320 ! snow with deciduous forest
Dutra et al., 2010
Snow albedo
Snow aging
)1(min,max, agesagess SS
dmm
tPS
PCTe
d
t
S
snownewage
rainsnowd
t
oldage
/20
02)1(
5.12
4
dmm
tPS
d
tS
snownewage
oldage
/5
28
Temporal evolution ofsnow albedo
Aging function S
New approach
1,
cr
snsn W
WMINf
1,
1.0
/ snsnsn
WMINf
Dutra et al., 2010
Wcr = 15mm
Hcr = 0.1m
1,
cr
snsn H
HMINf
Snow fraction
ROUTI
EXP
Snow Fraction ROUTI GME
Snow Fraction EXP GME
Snow Fraction ROUTI COSMO
Snow Fraction EXP COSMO
SYNOP VERIF EXP 8050 vs ROUTI18.12.10-30.01.11, 00 UTC
BIAS
RMSE
T2M TD2MD TMIN TMAX
PS DD FF VW
T2M TD2MD TMIN TMAX
PS DD FF VW
BIAS
T2M TD2MD TMIN TMAX
PS DD FF VW
RMSE
T2M TD2MD TMIN TMAX
PS DD FF VW
SYNOP VERIF EXP 8050 vs ROUTI31.01.11-28.02.11, 00 UTC
Snow melting 2011032112
Snow melting 2011032112
Snow melting 2011032112
Snow melting 2011032112
Snow melting 2011032112
BIAS
T2M TD2MD TMIN TMAX
PS DD FF VW
RMSE
T2M TD2MD TMIN TMAX
PS DD FF VW
SYNOP VERIF EXP 8032 vs ROUTI18.03.11-17.04.11, 00 UTC
SYNOP VERIF EXP 8033 vs ROUTI18.03.11-17.04.11, 00 UTC
BIAS
T2M TD2MD TMIN TMAX
PS DD FF VW
RMSE
T2M TD2MD TMIN TMAX
PS DD FF VW
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
SYNOP VERIF EXP 8050 vs ROUTIRANGE 1, 12 UTC, BIAS
SYNOP VERIF EXP 8050 vs ROUTIRANGE 1, 12 UTC, RMSE
SYNOP VERIF EXP 8050 vs ROUTIRANGE 2, 12 UTC, BIAS
SYNOP VERIF EXP 8050 vs ROUTIRANGE 2, 12 UTC, RMSE
