1. Kain-Fritsch convection scheme: an update Marco Arpagaus MeteoSwiss

2. Marco.Arpagaus@MeteoSwiss.ch COSMO General Meeting, 24-26 Sep 2003, Langen 1 Outline Good News and Bad News Some test-case results Improvements needed More sensitivity tests More output Conclusion and Outlook

3. Marco.Arpagaus@MeteoSwiss.ch COSMO General Meeting, 24-26 Sep 2003, Langen 2 Good News and Bad News Cleaned and reasonably well tested version available with LM version 3.6. However, still a lot to be tested and improved (see below). Poor performance on vector machines, but ok for MPPs; can not be optimized without substantial recoding. Alternative implementations of Tiedtke and Kain-Fritsch schemes available (from Peter Bechtold, ECMWF); will be added to the LM as alternative CPSs as soon as possible. Kain-Fritsch is already being experimentally used for the COSMO LEPS.

4. Marco.Arpagaus@MeteoSwiss.ch COSMO General Meeting, 24-26 Sep 2003, Langen 3 Some test-case results: 12.06.2003 00UTC Synoptic situation: High-pressure system over large parts of central Europe; convection over Switzerland in second half of the day. Poor forecast (complaints by forecasters) by aLMo: Can the Kain-Fritsch scheme provide a better forecast?

5. Marco.Arpagaus@MeteoSwiss.ch COSMO General Meeting, 24-26 Sep 2003, Langen 4 Some test-case results: 12.06.2003 00UTC Kain-Fritsch (nudging, GME)Tiedtke (nudging, GME) 09-12 UTC Kain-Fritsch (nudging, IFS)

6. Marco.Arpagaus@MeteoSwiss.ch COSMO General Meeting, 24-26 Sep 2003, Langen 5 Some test-case results: 12.06.2003 00UTC Kain-Fritsch (nudging, GME)Tiedtke (nudging, GME) 12-15 UTC Kain-Fritsch (nudging, IFS)

7. Marco.Arpagaus@MeteoSwiss.ch COSMO General Meeting, 24-26 Sep 2003, Langen 6 Some test-case results: 12.06.2003 00UTC Kain-Fritsch (nudging, GME)Tiedtke (nudging, GME) 15-18 UTC Kain-Fritsch (nudging, IFS)

8. Marco.Arpagaus@MeteoSwiss.ch COSMO General Meeting, 24-26 Sep 2003, Langen 7 Some test-case results: 12.06.2003 00UTC Kain-Fritsch (nudging, GME)Tiedtke (nudging, GME) 18-21 UTC Kain-Fritsch (nudging, IFS)

9. Marco.Arpagaus@MeteoSwiss.ch COSMO General Meeting, 24-26 Sep 2003, Langen 8 Some test-case results: 12.06.2003 00UTC Kain-Fritsch (nudging, GME)Tiedtke (nudging, GME) 21-24 UTC Kain-Fritsch (nudging, IFS)

10. Marco.Arpagaus@MeteoSwiss.ch COSMO General Meeting, 24-26 Sep 2003, Langen 9 Some test-case results: 24.07.2003 00UTC Synoptic situation: Retreat of a high-pressure ridge over southern Europe and passage of an upper-level trough; short- wave disturbance with associated cold front crosses Germany in the evening; pre-frontal convection in the afternoon. Poor forecast (complaints by forecasters) by LM at DWD: Can the Kain-Fritsch scheme provide a better forecast?

11. Marco.Arpagaus@MeteoSwiss.ch COSMO General Meeting, 24-26 Sep 2003, Langen 10 Some test-case results: 24.07.2003 00UTC Kain-Fritsch (nudging, GME)Tiedtke (nudging, GME) Kain-Fritsch (interpolation, GME) 12-18 UTC

12. Marco.Arpagaus@MeteoSwiss.ch COSMO General Meeting, 24-26 Sep 2003, Langen 11 Improvements needed Stripes of low precipitation amounts in the grid-scale precipitation output fields: insufficient removal of vertical instabilities? Related question: what are reasonable vertical velocities at the grid-scale? Did you observe any obvious shortcomings of the scheme?

13. Marco.Arpagaus@MeteoSwiss.ch COSMO General Meeting, 24-26 Sep 2003, Langen 12 More sensitivity tests Feedbacks provided by the Kain-Fritsch scheme temperature and water vapour only (same as Tiedtke scheme) temperature and all hydrometeors the host model ‘knows’ Trigger amount of temperature perturbation at the LCL dependence of temperature perturbation on vertical velocity and/or relative humidity sensitivity to averaging (of vertical velocity, forcing fields) Closure time scale Interplay of deep, shallow, and midlevel convection Dependence of scheme on calling frequency

14. Marco.Arpagaus@MeteoSwiss.ch COSMO General Meeting, 24-26 Sep 2003, Langen 13 More output cloud cover (for radiation scheme!) --- do it analogous to Tiedtke scheme? cloud base & cloud top CAPE, CIN massflux at cloud base …

15. Marco.Arpagaus@MeteoSwiss.ch COSMO General Meeting, 24-26 Sep 2003, Langen 14 Conclusion and Outlook Code available for extensive testing; experimental usage encouraged (feedback, please!). Missing output fields will be added within the next few weeks. Detailed case and sensitivity studies pending; anyone willing to do parallel runs (on MPPs …)? Implementation of alternative implementations of Tiedtke (IFS) and Kain-Fritsch (Meso-NH, Bechtold) schemes as soon as possible.

16. Marco.Arpagaus@MeteoSwiss.ch COSMO General Meeting, 24-26 Sep 2003, Langen 15 Some test-case results: 24.07.2003 00UTC Kain-Fritsch (nudging, GME)Tiedtke (nudging, GME) 12-18 UTC Kain-Fritsch (interpolation, GME)

17. Marco.Arpagaus@MeteoSwiss.ch COSMO General Meeting, 24-26 Sep 2003, Langen 16 Some test-case results: 24.07.2003 00UTC

18. Marco.Arpagaus@MeteoSwiss.ch COSMO General Meeting, 24-26 Sep 2003, Langen 17 Some test-case results: 24.07.2003 00UTC Kain-Fritsch (nudging, GME)Tiedtke (nudging, GME) 18-24 UTC Kain-Fritsch (interpolation, GME)