Recent developments at DWD christoph schraffdwd de Deutscher

Recent developments at DWD christoph. schraff@dwd. de Deutscher Wetterdienst, 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 Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de 1

nudging of radar radial velocity: methodology pre-processing , done twice (first use time, obs time) for each radar scan 1. 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 Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de 2

nudging of radar radial velocity: methodology 2. 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 get obs increments at model levels as weighted average of increments at obs points vertical cross section (weights depends on height differences) • pseudo obs (of radial velocity) = radial comp. of model wind + obs increment (at model level) (i, j) 20 km Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 2° christoph. schraff@dwd. de range model g. pts. 3

nudging of radar radial velocity: methodology horizontal plain processing in nudging at each time step : azimuth vpseudo vmod model grid pt. Radar upseudo umod • project current model wind to radial direction • current observation increment = pseudo observation of radial velocity - model radial velocity • increment : - physically: radial velocity - formally: wind vector, always in radial direction ! treat like radiosonde wind increment in nudging scheme pseudo observation in radial wind current model horizontal wind current model radial wind current increment in radial wind current target wind Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de 4

nudging of radar radial velocity: results shown last year 0 -UTC runs TSS control nudge vr FF-10 m RMSE s ter ! e x te te FF-10 m bias, all sta. n e r e l a n r m ara p sta. < 100 m f if d o t e u ed r ce n ere e w s 100 m < sta iff < 300 m e es d Th 300 m < sta < 800 m Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 sta. > 800 m christoph. schraff@dwd. de 5

nudging of radar radial velocity: verification against radar precipitation 1 – 27 May 2012 assimilation threshold: 0. 1 mm / h ETS control (COSMO-DE setup, with LHN) use of radial velocity added FBI Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de 6

nudging of radar radial velocity: verif. vs. radar precipitation (1 – 27 May 2012) threshold: 0. 1 mm / h ETS FSS, 11 g. pts. (30 km) control (C-DE setup, with LHN) use of radial velocity added 00 -UTC forecast runs 12 -UTC forecast runs Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de 7

nudging of radar radial velocity: verif. vs. radar precipitation (1 – 27 May 2012) threshold: 5. 0 mm / h ETS FSS, 11 g. pts. (30 km) control (C-DE setup, with LHN) use of radial velocity added 00 -UTC forecast runs 12 -UTC forecast runs Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de 8

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 !) : Ø small positive impact on (mainly strong) precipitation Ø otherwise neutral Ø 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 Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de 9

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 Germany • underestimation over southern Europe • underestimation in snow cases • lots of spurious ground echoes • software transforming it to COSMO grids available (Stephan) Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de 10

Status of OPERA ODC composite 12 Aug 2013, 15 UTC Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de

Status of 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 ? ) Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de Ref-Talk 19. 09. 2012 Radial Wind Assimilation

Status of OPERA • 3 -D reflectivity and radial wind: • reflectivity sent by almost all member states, radial wind only by few (but increasing) (Courtesy Hidde Leijnse, * 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)) Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de 13

Latent Heat Nudging for COSMO-EU Motivation • Reanalysis Project of HEr. Z would like to use LHN also on its larger domain configuration (COSMO-CORDEX, x = 7 km) • 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 V 4_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. 5 h in operational run) Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de 14

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 Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de

LHN for COSMO-EU: case study hourly precipitation at 2 Aug. 2012, 00 UTC + 4 h Radar Control (rout) Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 LHN Experiment christoph. schraff@dwd. de

LHN for COSMO-EU: SYNOP verification, summer: positive 12 UTC LHN ROUT Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de

LHN for COSMO-EU: SYNOP verification, winter: slightly positive 00 UTC LHN ROUT Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de

LHN for COSMO-EU: TEMP verification, summer / winter: neutral Experiment Control BIAS Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 RMSE christoph. schraff@dwd. de

LHN for COSMO-EU: Verification against radar precip (summer) Assimilation 0. 1 mm/h Assimilation LHN ROUT Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de

00 UTC 0. 1 mm/h 12 UTC 0. 1 mm/h Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 00 UTC 2. 0 mm/h 12 UTC 2. 0 mm/h christoph. schraff@dwd. de

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 Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de

Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de 23

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 Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de 24

nudging of radar radial velocity: example model (COSMO-DE) Azimuth Range (in m) observation southwesterly wind above 2500 m a. s. l. observation increment Range (in m) radial velocity at lowest elevation (0. 5°) of radar site Feldberg (30 Jan. 2012, 21 UTC). Nudging Radial Velocity, OPERA, LHN for COSMO-EU COSMO GM, Sibiu, 2 September 2013 christoph. schraff@dwd. de 25