Recent developments at DWD

1. Recent developments at DWD christoph.schraff@dwd.deDeutscherWetterdienst, D-63067 Offenbach, Germany based on experiments / plots by Klaus Stephan • Direct Nudging of Radar Radial Velocity Data • Status of OPERA • Latent Heat Nudging for COSMO-EU

2. nudging of radar radial velocity:methodology pre-processing , done twice (first use time, obs time) for each radar scan • at each observation point: • correct observed radial wind for sedimentation speed of the hydrometeors • calculate observation increment of radial wind component (at obs point) (requires: - bi-linear interpolation of model horizontal wind to obs point - project model horizontal wind to radial direction ) • re-folding aliased measurements (according to quality flags of the obs) • exclude all increments > ± 5 m/s

3. get obs increments at model levels as weighted average of increments at obs points (weights depends on height differences) range (i,j) (i,j) 2° model g. pts. 20 km nudging of radar radial velocity:methodology • at certain model grid points (i,j) (e.g. every 20 km lat / lon) : create vertical profiles of pseudo obs (of radial velocity, as a kind of superobbing) • assign all obs increments (at obs points) within ±1° (azimuth) and ±10 km (range) horizontally to this model grid point vertical cross section • pseudo obs (of radial velocity) = radial comp. of model wind + obs increment (at model level)

4. project current model wind to radial direction • current observation increment = pseudo observation of radial velocity - model radial velocity nudging of radar radial velocity:methodology processing in nudging at each time step : azimuth horizontal plain vpseudo • increment : - physically: radial velocity - formally: wind vector, always in radial direction !  treat like radiosonde wind increment in nudging scheme vmod model grid pt. upseudo umod pseudo observation in radial wind current model horizontal wind current model radial wind current increment in radial wind current target wind Radar

5. FF-10m bias, all sta. sta. < 100 m 100m < sta < 300m sta. > 800 m 300m < sta < 800m nudging of radar radial velocity:results shown last year 0-UTC runs TSS control nudge vr FF-10m RMSE These differences were due to different external parameters !

6. nudging of radar radial velocity:verification against radar precipitation 1 – 27 May 2012 assimilation threshold: 0.1 mm / h control (COSMO-DE setup, with LHN) use of radial velocity added ETS FBI

7. nudging of radar radial velocity:verif. vs. radar precipitation (1 – 27 May 2012) ETS FSS, 11 g.pts. (30 km) threshold: 0.1 mm / h control (C-DE setup, with LHN) use of radial velocity added 00-UTC forecast runs 12-UTC forecast runs

8. nudging of radar radial velocity:verif. vs. radar precipitation (1 – 27 May 2012) ETS FSS, 11 g.pts. (30 km) threshold: 5.0 mm / h control (C-DE setup, with LHN) use of radial velocity added 00-UTC forecast runs 12-UTC forecast runs

9. nudging of radar radial velocity:summary • nudging of radar radial velocity implemented • still code problems with reproducibility (some error rel. to MPI communication) • experiment May 2012 with additional use of vr (control with LHN !) : • small positive impact on (mainly strong) precipitation • otherwise neutral • no show cases with strong positive impact • next: • fix reproducibility problem, clean up code, • check and improve efficiency • include in official COSMO version, • add few more tests, • make it operational

10. Status of OPERA • currently 27 member states with about 160 radar stations • OPERA Phase 4 : spring 2013 – 2018 • Programme manager Elena Saltikoff (FMI) • User Group established (total 11 p. from NWP, hydrology, biology) • three 2-D composites are available every 15 minutes: • current rain rate, sum over last hour, current maximum reflectivity • Phillipe Lopez (ECMWF) found out: • quality has increased in 2013 (with Baltrad QC) but is still not sufficient everywhere • best quality over UK, France, Poland and Germany • underestimation over southern Europe • underestimation in snow cases • lots of spurious ground echoes • software transforming it to COSMO grids available (Stephan)

11. Status of OPERA ODC composite 12 Aug 2013, 15 UTC

12. Status of OPERA OPERA DC composite (C-DE domain): 1 Z-R relationship ‘EY composite: Input for LHN at DWD, 4 different storm-dep. Z-R relationships 12 Aug. 2013 15 UTC differences particularly for low precip rates; (erroneous spaital alignment ?)

13. Status of OPERA • 3-D reflectivity and radial wind: • reflectivity sent by almost all member states, • radial wind only by few • (but increasing) • (Courtesy HiddeLeijnse, * indicates max. number) • HIRLAM already gets access to volume data, but possible also for other consortia • dissemination of volume data to member states planned for end of 2014 • (to be decided: with or without quality information ?) • discussion about meta data / quality issues are ongoing • (e.g. to distinguish ‘zero echo’ – ‘no data’ (compare with raw data))

14. Latent Heat Nudging for COSMO-EU • Motivation • Reanalysis Project of HErZ would like to use LHN also on its larger domainconfiguration (COSMO-CORDEX, x = 7km) • Does it work ? • Is there a negative interaction between LHN and the deep convection scheme ? • Experiments • 2 periods: Summer: August 2012 (incl. convective cases) • Winter: 1 Nov. – 15 Dec. 2012 (incl. snow cases) • operational COSMO-EU setup (Cosmo V4_27, tk?min=0.4) • operational LHN setup except: • no blacklist information used • no bright band detection • LHN within first 25 minutes of forecast (will be ~ 2.5h in operational run)

15. LHN for COSMO-EU: radar data coverage • same data as for COSMO-DE, currently • 17 German Doppler radar stations quality controlled • 2 Dutch stations • 2 Belgian stations • 9 France stations • 3 Swiss stations • 2 Czech stations soon extended by 2 Polish stations • every 5 minutes • future: can be extended by OPERA composite outside COSMO-DE domain

16. LHN for COSMO-EU: case study hourly precipitation at 2 Aug. 2012, 00 UTC + 4h Radar Control (rout) LHN Experiment

17. LHN for COSMO-EU: SYNOP verification, summer: positive 12 UTC LHN ROUT

18. LHN for COSMO-EU: SYNOP verification, winter: slightly positive 00 UTC LHN ROUT

19. LHN for COSMO-EU: TEMP verification, summer / winter: neutral Experiment Control BIAS RMSE

20. LHN for COSMO-EU: Verification against radar precip (summer) Assimilation 0.1 mm/h Assimilation 0.1 mm/h LHN ROUT

21. 00 UTC 0.1 mm/h 00 UTC 2.0 mm/h 12 UTC 0.1 mm/h 12 UTC 2.0 mm/h

22. LHN for COSMO-EU: Summary • LHN in COSMO-EU is beneficial; forecast impact: • Summer: • precipitation improved (esp. convective cases) • most surface parameters improved • Winter: • most surface parameter slightly improved • impact on precipitation and low stratus neutral • Work started to extend data coverage using OPERA radar composite

24. nudging of radar radial velocity:verification against radar precipitation 1 – 27 May 2012 precipitation against radar FSS , 11 g.pts. (30 km) threshold : 2 mm / h assimilation control (COSMO-DE setup, with LHN) use of radial velocity added 00-UTC forecast runs 12-UTC forecast runs

25. nudging of radar radial velocity:example model (COSMO-DE) observation Range (in m) Azimuth Azimuth observation increment radial velocity at lowest elevation (0.5°) of radar site Feldberg (30 Jan. 2012, 21 UTC). Range (in m) southwesterly wind above 2500 m a.s.l.