The COSMO-LEPS cloud problem over the Alpine region

Eidgenössisches Departement des Innern EDIBundesamt für Meteorologie und Klimatologie MeteoSchweiz

The COSMO-LEPS cloud problem over the Alpine region

André Walser

MeteoSwiss

COSMO General Meeting, Moscow, 6-10 September 2010

2 COSMO-LEPS cloud problem | COSMO GM 2010André Walser ([email protected])

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

00 UTC 00 UTC

ObservationsCOSMO-LEPS ensemble meanCOSMO-7

~1K

lead-time +(25-48)h


SYNOP verif T_2M CH JJA2010

~2K

ObservationsCOSMO-LEPS ensemble meanCOSMO-7

lead-time +(25-48)h

00 UTC 00 UTC


SYNOP verif CLCT CH JJA2010

20

-20

00 UTC 00 UTC

lead-time +(25-48)h

COSMO-LEPS ensemble meanCOSMO-7

0

Mea

n E

rro

r


SYNOP verif CLCT Europe JJA2010COSMO-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)

member 7

Low-level cloud cover (CLCL)

member 7


Low level clouds (CLCL)


Low level clouds (CLCL)


Member configurationitype_conv=1turlen=150pat_len=500crsmin=50rat_sea=40rlam_heat=0.1

itype_conv=1turlen=500pat_len=2000crsmin=50rat_sea=20rlam_heat=1

itype_conv=1turlen=1000pat_len=5000crsmin=50rat_sea=1rlam_heat=0.1















Member configurationitype_conv=1turlen=150pat_len=500crsmin=50rat_sea=40rlam_heat=0.1

















Tiedtke Kain-Fritsch

~10-15 % higher, but mainly for high cloud cover cases

V.Stauch

Impact on CLCT (4 weeks in summer 2010):

COSMO-7 Kain-Fritsch test-suite (1)


00 UTC 00 UTC

ObservationsTiedtkeKain-FritschIFS


SYNOP verif T_2M Switzerland (lead-time +(01-24)h):



• 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]

4

8

12

16

12:00 23.06. 00:00 24.06. 12:00 24.06. 00:00 25.06.

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

obsKain-Fritsch membersTiedtke members


SYNOP verif TD_2M CH JJA2010

00 UTC 00 UTC

Mea

n E

rro

r

0

3

-3

COSMO-LEPS ensemble meanCOSMO-7


SYNOP verif TD_2M Europe JJA2010

COSMO-LEPS ensemble mean of TD_2M: Mean error


Soil moisture: typical summer case

COSMO-LEPS memberinitial conditions

COSMO-7initial conditions

leve

l 1

(0-1

cm)

[mm]

wet Alpine region in COSMO-LEPS





leve

l 2

(1-3

cm)

[mm]






leve

l 3

(3-9

cm)

[mm]






leve

l 4

(9-2

7cm

)

[mm]



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

Documents

The COSMO-LEPS cloud problem over the Alpine region