The COSMO-LEPS cloud problem over the Alpine region André Walser MeteoSwiss COSMO General Meeting, Moscow, 6-10 September 2010

Typical summer case… COSMO-LEPS median COSMO-7 Observations  many members with a too small diurnal cycle in 2m temperature  COSMO-LEPS predicts clearly more clouds than COSMO-7  large spread in deterministic case

SYNOP verif T_2M Europe JJA2010 lead-time +(25-48)h ~1K Observations COSMO-LEPS ensemble mean COSMO-7 00 UTC 00 UTC

SYNOP verif T_2M CH JJA2010 ~2K Observations COSMO-LEPS ensemble mean lead-time +(25-48)h ~2K Observations COSMO-LEPS ensemble mean COSMO-7 00 UTC 00 UTC

SYNOP verif CLCT CH JJA2010 20 Mean Error COSMO-LEPS ensemble mean lead-time +(25-48)h Mean Error COSMO-LEPS ensemble mean COSMO-7 -20 00 UTC 00 UTC

SYNOP verif CLCT Europe JJA2010 COSMO-LEPS ensemble mean of CLCT: Mean error

June 24 case COSMO-LEPS median COSMO-7 Observations

June 24 15 UTC: A sunny day...

June 24 15 UTC:COSMO-LEPS Total cloud cover (CLCT) Low-level cloud cover (CLCL) member 7 member 7

Low level clouds (CLCL)

Low level clouds (CLCL)

Member configuration itype_conv=1 turlen=150 pat_len=500 crsmin=50 rat_sea=40 rlam_heat=0.1 turlen=500 pat_len=2000 rat_sea=20 rlam_heat=1 turlen=1000 pat_len=5000 rat_sea=1 rlam_heat=5 itype_conv=0 crsmin=150 crsmin=200

Member configuration itype_conv=1 turlen=150 pat_len=500 crsmin=50 rat_sea=40 rlam_heat=0.1 turlen=500 pat_len=2000 rat_sea=20 rlam_heat=1 turlen=1000 pat_len=5000 rat_sea=1 rlam_heat=5 itype_conv=0 crsmin=150 crsmin=200

COSMO-7 Kain-Fritsch test-suite (1) Impact on CLCT (4 weeks in summer 2010): Tiedtke Kain-Fritsch ~10-15 % higher, but mainly for high cloud cover cases V.Stauch

COSMO-7 Kain-Fritsch test-suite (2) SYNOP verif T_2M Switzerland (lead-time +(01-24)h): 00 UTC Observations Tiedtke Kain-Fritsch IFS

COSMO-7 Kain-Fritsch test-suite (3) Overestimation of cloud cover for northern Europe (but not for Switzerland) Impact on diurnal cycle of 2m temperature for Switzerland very small  For entire results see talk about comparison of Tiedtke, Kain-Fritsch and IFS convection schemes in WG3  Results suggest that Kain-Fritsch alone cannot explain the COSMO-LEPS cloud problem

June case: Too moist boundary layer COSMO-LEPS TD_2M and OBS @ Zurich SYNOP station [oC] Kain-Fritsch members Tiedtke members

SYNOP verif TD_2M CH JJA2010 3 Mean Error COSMO-LEPS ensemble mean COSMO-LEPS ensemble mean COSMO-7 -3 00 UTC 00 UTC

SYNOP verif TD_2M Europe JJA2010 COSMO-LEPS ensemble mean of TD_2M: Mean error

Soil moisture: typical summer case COSMO-LEPS member initial conditions COSMO-7 initial conditions [mm] level 1 (0-1cm)  wet Alpine region in COSMO-LEPS

COSMO-LEPS member initial conditions COSMO-7 initial conditions Soil moisture: typical summer case COSMO-LEPS member initial conditions COSMO-7 initial conditions [mm] level 2 (1-3cm)  wet Alpine region in COSMO-LEPS

COSMO-LEPS member initial conditions COSMO-7 initial conditions Soil moisture: typical summer case COSMO-LEPS member initial conditions COSMO-7 initial conditions [mm] level 3 (3-9cm)  wet Alpine region in COSMO-LEPS

COSMO-LEPS member initial conditions COSMO-7 initial conditions Soil moisture: typical summer case COSMO-LEPS member initial conditions COSMO-7 initial conditions [mm] level 4 (9-27cm)  wet Alpine region in COSMO-LEPS

Conclusions Cloud problem in COSMO-LEPS seems to be caused by Kain-Fritsch together with a too moist boundary layer Has dramatic impact on 2m temperature Too moist boundary layer is caused by a too moist soil  Soil merge (COSMO-EU or assimilation cycle) should be introduced as soon as possible If not possible before spring 2011, skip Kain-Fritsch When problems with IFS convection scheme are solved ( WG3 talk) consider to use it  Soil moisture should be added to COSMO-LEPS output