1. Federal Department of Home Affairs FDHA Federal Office of Meteorology and Climatology MeteoSwiss Sensitivity studies for the Swiss test cases LM User Seminar, 8 March 2007, Langen S. Dierer MeteoSwiss

2. 2 Swiss cases S. Dierer Selection of test cases Based on operational forecasts for Switzerland 2005 Selection of 24h area mean of precipitation less than 50% or more than 200% of the measured area mean precipitation (ANETZ verification) about 52 days, more or less the same number per season Excluding days with very light or localized precipitation resulting in 21 days (7 winter, 4 spring, 6 summer and 4 autumn) Selection based on weather situation and kind of error, excluding cases with the „same error“ on different days List of 8 days Simulation with the reference version change of model version (LM 3.19) change of boundary values (IFS/GME) 4 cases change significantly, 4 remain similar Final list: 2.2.; 22.3.; 12.7.; 17.12.

3. 3 Swiss cases S. Dierer Description of test case 02.02.2005 Northerly flow at 500 hPa occluded front in the northern part Mainly stratiform Overestimation of mean and maximum precipitation Overestimation at northern slopes of the mountains Typical for situations with northerly flow

4. 4 Swiss cases S. Dierer 24h area mean precipitation for 02.02.2005 11 micro1 12 micro2 13 micro3 14 conmod 15 conkfb 16 conoff 17 rlam01 18 rlam50 19 sto050 20 sto250 21 sea01 22 sea40 O ctrl 1 wso80 2 Wso120 3 Qv090 4 Qv110 5 dt20 6 lfsl3 7 Rksl3 8 rkbott 9 rktp 10 oro

5. 5 Swiss cases S. Dierer 24h maximum precipitation for 02.02.2005 11 micro1 12 micro2 13 micro3 14 conmod 15 conkfb 16 conoff 17 rlam01 18 rlam50 19 sto050 20 sto250 21 sea01 22 sea40 O ctrl 1 wso80 2 Wso120 3 Qv090 4 Qv110 5 dt20 6 lfsl3 7 Rksl3 8 rkbott 9 rktp 10 oro

6. 6 Swiss cases S. Dierer Description of test case 22.03.2005 southwesterly flow at 500 hPa warm front in the northern part Stratiform Overestimation of mean precipitation (region too large) Overestimation in the eastern part of CH

7. 7 Swiss cases S. Dierer 24h area mean precipitation for 22.03.2005 11 micro1 12 micro2 13 micro3 14 conmod 15 conkfb 16 conoff 17 rlam01 18 rlam50 19 sto050 20 sto250 21 sea01 22 sea40 O ctrl 1 wso80 2 Wso120 3 Qv090 4 Qv110 5 dt20 6 lfsl3 7 Rksl3 8 rkbott 9 rktp 10 oro

8. 8 Swiss cases S. Dierer 24h maximum precipitation for 22.03.2005 11 micro1 12 micro2 13 micro3 14 conmod 15 conkfb 16 conoff 17 rlam01 18 rlam50 19 sto050 20 sto250 21 sea01 22 sea40 O ctrl 1 wso80 2 Wso120 3 Qv090 4 Qv110 5 dt20 6 lfsl3 7 Rksl3 8 rkbott 9 rktp 10 oro

9. 9 Swiss cases S. Dierer Description of test case 12.07.2005 Northeasterly flow at 500 hPa convective Error in mean and maximum precipitation, maximum too low Observed: strong thunderstorms in the southern part of CH, simulated less intense convective precipitation in the eastern part of CH

10. 10 Swiss cases S. Dierer 24h mean precipitation for 12.07.2005 11 micro1 12 micro2 13 micro3 14 conmod 15 conkfb 16 conoff 17 rlam01 18 rlam50 19 sto050 20 sto250 21 sea01 22 sea40 O ctrl 1 wso80 2 Wso120 3 Qv090 4 Qv110 5 dt20 6 lfsl3 7 Rksl3 8 rkbott 9 rktp 10 oro

11. 11 Swiss cases S. Dierer 24h maximum precipitation for 12.07.2005 11 micro1 12 micro2 13 micro3 14 conmod 15 conkfb 16 conoff 17 rlam01 18 rlam50 19 sto050 20 sto250 21 sea01 22 sea40 O ctrl 1 wso80 2 Wso120 3 Qv090 4 Qv110 5 dt20 6 lfsl3 7 Rksl3 8 rkbott 9 rktp 10 oro

12. 12 Swiss cases S. Dierer Description of test case 17.12.2005 Northwesterly flow at 500 hPa Mainly stratiform with convective part Overestimation of mean and maximum precipitation Overestimation at the northern slopes of the mountains Typical for situations with northwesterly flow Similar to 02.02.2005

13. 13 Swiss cases S. Dierer 24h area mean precipitation for 17.12.2005 11 micro1 12 micro2 13 micro3 14 conmod 15 conkfb 16 conoff 17 rlam01 18 rlam50 19 sto050 20 sto250 21 sea01 22 sea40 O ctrl 1 wso80 2 Wso120 3 Qv090 4 Qv110 5 dt20 6 lfsl3 7 Rksl3 8 rkbott 9 rktp 10 oro

14. 14 Swiss cases S. Dierer 24h maximum precipitation for 17.12.2005 11 micro1 12 micro2 13 micro3 14 conmod 15 conkfb 16 conoff 17 rlam01 18 rlam50 19 sto050 20 sto250 21 sea01 22 sea40 O ctrl 1 wso80 2 Wso120 3 Qv090 4 Qv110 5 dt20 6 lfsl3 7 Rksl3 8 rkbott 9 rktp 10 oro

15. 15 Swiss cases S. Dierer CTRL versus QV90 (Exp. 3), 02.02.2005

16. 16 Swiss cases S. Dierer CTRL versus QV90 (Exp. 3), 22.03.2005

17. 17 Swiss cases S. Dierer CTRL versus QV90 (Exp. 3), 12.07.2005

18. 18 Swiss cases S. Dierer CTRL versus RKsl3 (Exp. 7), 02.02.2005

19. 19 Swiss cases S. Dierer CTRL versus RKsl3 (Exp. 7), 17.12.2005

20. 20 Swiss cases S. Dierer Summary 1 Stratiform and mainly stratiform cases Reduction of initial humidity causes strong reduction of precipitation except for the case of 17.12.2005 02.02.2005: about 13%, homogeneous 22.03.2005: about 33%, homogeneous (most important) Change from Leapfrog to Runge-Kutta most important change for 02.02.2005 and 17.12.2005 (about 20% reduction), small reduction (about 8%) for 22.03.2005 Reduction seems to act quite homogeneous Micro2 reduces mean precipitation in case 17.12.2005 (about 20%), micro3 no effect for 17.12.2005 Changes of 02.02.2005 and 17.12.2005 not as similar as expected 02.02.2005: QV90 and RKs 17.12.2005: RKs, micro2, KFB and conoff

21. 21 Swiss cases S. Dierer Summary 2 Convective case Reduction of initial humidity causes strong reduction of precipitation 12.07.2005: about 45%, also changing structure (most important) Change from Leapfrog to Runge-Kutta has no effect for 12.07.2005 Micro2 reduces mean precipitation in case 12.07.2005 (about 20%), micro3 similar effect

22. 22 Swiss cases S. Dierer Summary 3 Smaller effects Reduced time step causes smaller effects (5-10% - 3 reductions, 1 increase) Reduced vertical exchange reduces precipitation amount by about 5-10% In two of the cases Runge-Kutta with semi-Lagrange tricubic advection gives unrealistic high maximum values Next steps: ANETZ verification for cases with changes Check against radio soundings if humidity is O.K. understand changes (e.g. reduction of mean precipitation due to Runge-Kutta or decreased vertical exchange and changes due to decreased time step)

23. 23 Swiss cases S. Dierer CTRL versus RKbott (Exp. 8), 02.02.2005

24. 24 Swiss cases S. Dierer CTRL versus RKtp (Exp. 9), 02.02.2005

25. 25 Swiss cases S. Dierer CTRL versus micro2 (Exp. 12), 02.02.2005

26. 26 Swiss cases S. Dierer CTRL versus RLAM50 (Exp. 18), 02.02.2005

27. 27 Swiss cases S. Dierer CTRL versus DT20 (Exp. 5), 22.03.2005

28. 28 Swiss cases S. Dierer CTRL versus RLAM50 (Exp. 18), 22.03.2005

29. 29 Swiss cases S. Dierer CTRL versus RKtp (Exp. 9), 21.07.2005

30. 30 Swiss cases S. Dierer CTRL versus micro1 (Exp. 11), 12.07.2005

31. 31 Swiss cases S. Dierer CTRL versus micro2 (Exp. 12), 12.07.2005

32. 32 Swiss cases S. Dierer CTRL versus micro3 (Exp. 13), 12.07.2005

33. 33 Swiss cases S. Dierer CTRL versus conmod (Exp. 14), 12.07.2005

34. 34 Swiss cases S. Dierer CTRL versus KFB (Exp. 15), 12.07.2005

35. 35 Swiss cases S. Dierer CTRL versus RKbott (Exp. 8), 17.12.2005

36. 36 Swiss cases S. Dierer CTRL versus RKtp (Exp. 9), 17.12.2005

37. 37 Swiss cases S. Dierer CTRL versus micro2 (Exp. 12), 17.12.2005

38. 38 Swiss cases S. Dierer CTRL versus KFB (Exp. 15), 17.12.2005