Mesoscale model experience with UM at met.no

1. Mesoscale model experience with UM at met.no HIRLAM-ALADIN-MF miniworkshop 12/12/05 Dag Bjørge

2. NWP collaboration in Europe

3. Short version of UM history at met.no • 2002: Met Office–met.no NWP collaboration • 2003: UM 3km, S-Norway grid, forced by Met Office 20km and Hirlam 10km • 2004: UM 4km, Norway grid, forced by HL 10km • 2005: ”UM4XL”, Norway/Sweden grid • Nov2005: UM 1km, 3 small grids nested into UM4XL

4. How does it perform ?

5. Temperature

8. How is the UM model set up ? • Climate and parameter files from Met Office ”ancil generation” software • LBC’s from Hirlam 10km, interpolation with ”hl2um” ( a met.no mixture of subroutines from UM and Hirlam ) • Some surface fields from Hirlam … • Some fields from previous +12h forecast …

9. 300 * 500 * 38 gridpoints, • 4km resolution, 100s timestep • Hourly postprocessing of surface fields, 3 hourly pressure levels, 6 hourly model levels • Boundary fields written out every 20 minutes for +8h to +21h, for nesting of 3 UM 1km grids • Runs on 280 CPUs, at 00UTC and 12UTC • 48h forecast in ~1h45min • SGI Origin 3800 ( to be replaced next year )

10. What does it look like ? • Quasi operational runs • Different experiments • Temperature problem solved (last week)

11. The model chain at met.no • The ”turbulence project” is used to describe the different models we now have available for forecasting at global to local ( airport ) scale.

12. Why a turbulence project ? ”På grunn av variable og vanskelige vindforhold bestemte kapteinen seg for å avbryte landinga. Da kom det et kraftig vindkast, og flyet smalt i bakken.”

13. Orography and resolution ( ”Seven sisters” )

14. LBCs (~50km) for Hirlam20 and Hirlam10 at 3 hour intervals ( usually 6 hours old )

15. Hirlam10 • Starts from interpolated Hirlam20-analysis • Boundaries ( frames ) from ECMWF • Writes ”model dumps” / ”history files” every hour for nesting of Met Office Unified Model ( UM4 )

16. Hirlam10 and UM4

17. UM 4km with three UM 1km grids

18. The ”lifetime” of LBCs in a small grid 30min intervals

19. UM1 • Starts for all airports as soon as UM4 has reached it’s +21 hour forecast • UM1 starts at UM4 +8h forecast, spins up for one hour • Writes full model dumps at +9, +12, +15, +18 and +21 • The turbulence model called ”Simra” is then run for each of these instances

20. Operational cycles • The model system as described is run twice a day at 00UTC and 12UTC • Results are continously updated through the run, and can be studied as the forecast is produced

21. UM1, Sandnessjøen

22. Example of product, inflight cone

23. Example of product, inflight turbulence in cross section

24. Some examples of different treatment of precipitation in the different models

25. ”Precipitation shaddow”, Hirlam / UM

26. Tromsø-area, Hirlam10 and UM4

27. Structure of precipitation, HL20/10, UM4, radar

28. Ad hoc setup of UM for the Barents sea • Example showing a ”polar low”

29. Polar low in UM 4km

30. Hirlam10 og UM4

31. UM4 +23h, mslp and wind

32. Temperature problem ( solved last week ) • um505_thetamono_no.mf77 • A fix for the valley cooling problem. It is an active area of investigation and we may come up with alternative/better solutions, but this will hopefully work in the short term.

36. Comparing Hirlam and UM • Hirlam has been set up on exactly the same ( horizontal ) grid as UM4XL • Hirlam version 6.4.1+ • H04 runs started in November on the met.no Linux cluster • Some technical difficulties … • Computer resources (SGI) : UM = 3 * HL

37. Heavy precipitation and flooding at the western coast of Norway in November

39. Hirlam 4km UM 4km

40. Hirlam 4km, 12h accumulated precip

41. UM 4km, 12h accumulated precip