1. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 Recents Improvements in LMZ Code Lucio TORRISI CNMCA – Pratica di Mare (Rome) l.torrisi@meteoam.it

2. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 Introduction A z-coordinate version of LM (LMZ) has been developed at DWD using the cut cell approach (Steppeler et al., 2002: MWR). LMZ should provide more accurate precipitation and wind forecasts in mountainous regions than the terrain following coordinate version of LM (LMTF). LMZ core needs to be intensively tested and evaluated, before other development effort is done. A number of real forecast tests with LMZ/LMTF was performed (Steppeler and Torrisi, 2006: Adv. Num. Sem. presentation). An improvement in total precipitation forecast associated with small amount of convective precipitation was found for LMZ.

3. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 Overview LM/LMZ configuration. Problem: underestimation of convection Problems in parallel machines Case study: precipitation plots for LMZ, LMTF and LMTF op. Summary Proposal for future developments

4. Lucio Torrisi WG2-COSMO GM, Bucharest 2006

5. EXPERIMENTAL RUN ON FUJITSU (ECMWF) LM CONFIGURATION (version 2.10) Domain size465 x 385 (previous EuroLM domain) Grid spacing0.0625 (7 km) Number of layers35 Time step10 sec Forecast range30 hrs Initial time of model run00 UTC Lateral boundary conditions and initial stateOp. IFS (preproc. with CNMCA-IFS2LM) L.B.C. update frequency3 hrs OrographyFiltered (eps = 0.1) + Extra Filtering Prognostic precipitationOff Turbulence parameterizationExplicit Prognostic TKE (imode_turb=2) Interval between two calls of turbulence1 time step Turbulence parameterization R.damping: filter iteration number10 R. damping: filter length1 LM (3.20+) and LMZ (1.5+) configuration Domain size234 x 272 Grid spacing0.0625 (7 km) Number of layers35 Time step and integration scheme40 sec, 3 timelevel split-explicit Forecast range48 hrs Initial time of model run00/12 UTC Lateral boundary conditionsGME L.B.C. update frequency1 hrs Initial stateGME InitializationD. F. External analysisNone StatusOperational HardwareIBM SP3 (Bologna) N° of processors used64

6. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Acc.Total Precipitation: LMZ Old code: spline interpolation of phys./dyn. tendencies and imode_turb=2

7. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Convective Rain: LMZ Old code: spline interpolation of phys./dyn. tendencies and imode_turb=2

8. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 Underestimation of Convective Precipitation in LMZ Error in the trigger of convection, since dqvdt (qv advection + qv vertical turbulent flux) and qvsflx (qv surface flux) not computed –qv vertical turbulent flux for imode_turb=2 (qvtens in turbdiff) added to dqvdt (for imode_turb=1 explicit correction not added; fixed also in LM official code) –qv advection interpolated to physics grid (in swap_tendencies) and added to dqvdt –qvsflx computed (in z_slow_tendencies) Error in the computation of physical tendencies, since radiation and convection tendencies not added to the other ones (in src_z_leapfrog).

9. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 LMZ on Parallel Machines Other bugs were found running LMZ on parallel machines: –boundary exchange of wind tendencies in TKE prognostic turbulence scheme missing (only for imode_turb=2 in turbdiff) –uncorrect final index in computation of flux limiters (in fluxlim) –extension of subdomain size for a correct setting of horizontal boundary conditions in cut cells missing (in z_horizontal_advection) LMZ 1.5 upgrade to LM 3.20 (CIRA performed that one to 3.17) including also the option of the spline interpolation of phys./dyn. tendencies present in LMZ 1.4.

10. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Acc.Total Precipitation: LMZ Spline interpolation of physical tendencies and imode_turb=2

11. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Acc.Total Precipitation: LMZ Linear interpolation of phys./dyn. tendencies and imode_turb=2

12. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Acc. Rain: Sp./Lin. Int. Tend. LMZ LMZ (Lin.Int.Tend.) Convective Grid-scale LMZ (Spl.Int.Tend.)

13. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 Old LMZ LMZ 6h Accumulated Rain: Old/New LMZ Convective Grid-scale

14. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Acc.Total Precipitation: LMTF imode_turb=2

15. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Acc.Total Precipitation: LMTF/LMZ LMTF LMZ FC 00-06 h FC 06-12 h

16. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Acc.Total Precipitation: LMTF/LMZ FC 12-18 h FC 18-24 h LMTF LMZ

17. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Acc.Total Precipitation: LMTF/LMZ LMTF LMZ FC 24-30 h

18. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Accumulated Rain: LMTF/LMZ LMZ LMTF Convective Grid-scale

19. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Acc.Total Precipitation: LMTF (op.) Implicit prognostic TKE turbulence scheme (imode_turb=1) + bug correction

20. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Acc. Tot. Precipit.: LMTF (op.)/LMZ LMTF (op.) LMZ FC 00-06 h FC 06-12 h

21. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Acc. Tot. Precipit.: LMTF (op.)/LMZ FC 12-18 h FC 18-24 h LMTF (op.) LMZ

22. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Acc. Tot. Precipit.: LMTF (op.)/LMZ LMTF (op.) LMZ FC 24-30 h

23. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Accum. Rain: LMTF (op.) / LMZ LMZ Convective Grid-scale LMTF (op.)

24. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Acc. Tot. Precipit.: LMTF (op.)/LMTF LMTF (op.) LMTF FC 00-06 h FC 06-12 h

25. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Acc. Tot. Precipit.: LMTF (op.)/LMTF FC 12-18 h FC 18-24 h LMTF (op.) LMTF

26. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Acc. Tot. Precipit.: LMTF (op.)/LMTF LMTF (op.) LMTF FC 24-30 h

27. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 6h Accum. Rain: LMTF (op.) / LMTF Convective Grid-scale LMTF (op.)LMTF

28. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 Accumul. Precipitation Comparison Domain mean (max) 30 hr total precipitation 1.667 (177.1)2.933 (177.5)1.863 (110.4) Domain mean (max) 30 hr grid-scale rain.7413 (51.4)1.004 (140.2).9212 (96.5) Domain mean (max) 30 hr convective rain.9138 (176.9)1.889 (110.1).9075 (62.3) LMZ LMTF LMTF op.

29. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 Objective verification results

30. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 Objective verification results ~ 100 events LMTF op. for this case study seems to be better than LMZ. LMTF produces a larger amount of precipitation than LMZ and LMTF. Does the explicit TKE prognostic turbulence scheme work correctly?

31. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 Objective verification results ~ 850 fc-obs

32. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 Some bugs were fixed in LMZ code for solving the underestimation of convection precipitation and the problems with parallel machines. The spline interpolation of the dynamical / physical tendencies does not seem to work correctly (spots of very large precipitation). The linear one seems to give satisfying results. For a case study, LMZ forecasts less and slightly smoother precipitation than LMTF. The amount of accumulated total precipitation of LMTF op. (imode_turb=1) and LMZ are pretty similar. LMTF op. forecasts less convective precipitation than LMTF. Comparison of surface variable forecasts with observations shows that LMTF op. performs better than LMZ and LMTF. Summary

33. Lucio Torrisi WG2-COSMO GM, Bucharest 2006 Wait for new LM 3.21, upgrade LMZ to this version and release new LMZ (1.6?) Include recent improvements in z-dynamics on the new version Improve computational efficiency of z- coordinate code Other: implicit vertical advection, use of implicit turbulence parameterization, microphysics, etc. Proposal for Future Developments