1. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 1 Status Report PP KENDA Christoph Schraff Deutscher Wetterdienst, Offenbach, Germany Contributions / input by: Hendrik Reich, Andreas Rhodin, Annika Schomburg, Ulrich Blahak, Yuefei Zeng, Roland Potthast Yuefei Zeng, Klaus Stephan, Africa Perianez, Michael Bender (DWD) Chiara Marsigli, Tiziana Paccagnella (ARPA-SIM) Lucio Torrisi (CNMCA) Daniel Leuenberger, Luca Weber (MeteoSwiss) Mikhail Tsyrulnikov, Igor Mamay (HMC) Amalia Iriza (NMA) general overview assimilation of SEVIRI-derived cloud top height in LETKF

2. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 2 LETKF: implementation experiment chain in NUMEX set up GME LETKF exp. (N ens = 40) June 2011 for lateral BC: somewhat too little spread particularly over Europe, but LBC spread at least as large as from COSMO-SREPS (N ens = 12) ana. spread ana. rmse for COSMO-LETKF:. lateral BC by direct interpolation from 60 km to 2.8 km (moderate noise at model top & surface, acceptable) MCH / ARPA-SIM: resolution gap IFS-EPS (32 km to 2.8 km) tested: ok

3. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 3 LETKF: implementation experiment chain in NUMEX set up lateral BC by direct interpolation from 60 km to 2.8 km KENDA: –1-hourly cycling, radiosonde, aircraft, wind profiler, synop; 40 ens. members –assimilation only, optimally takes ~ 1 real day for 1 day of assimilation, but in fact: ~ 1 – 4 real months for 1 week of assimilation ! (without forecasts !!)  only 3 experiments so far Hendrik: new flexible stand-alone scripts to run LETKF experiments without using NUMEX / archive  very limited disk space  1 real day for 1 day of LETKF assimilation to do: implement evaluation / verification tools in script suite may become very suitable tool for users outside DWD (academia) offline adaptive estimation of obs errors in observation space multi-step analysis approach (different localization radii for different sets of obs)

4. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 4 LETKF: ensemble forecasts (20 ens. members) KENDA / COSMO-DE-EPS max. 10-m wind gusts2-m temperature precipitation  results of LETKF (without explicit surface / soil perturbations) : 4 – 12 June 2011 larger rmse, initially larger spread larger rmse, equal spread larger rmse, larger spread RMSE spread

5. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 5 LETKF technically works comparison with surface observations suggest –generally: LETKF better than NO_OBS, but worse than nudging –assimilation of surface pressure appears to work particularly well LETKF_DET analysis very close to LETKF ensemble mean SPPT has only small but positive impact LETKF at MCH, compare det. LETKF analysis with nudging COSMO-2, N ens = 40, LETKF as at DWD lateral BC from IFS (det./EPS); soil moisture from COSMO-2

6. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 6 LETKF: implementation of verification production of ‘full’ NetCDF feedback files done:COSMO observation operators (conventional obs) integrated in 3DVAR package to be done (this autumn !) : extend flow control (read correct Grib files etc.) ensemble-related diagnostic + verification tool, using feedback files : (Iriza, NMA) – ensemble scores implemented, further testing required

7. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 7 accounting for model error stochastic perturbation of physics tendencies (SPPT) (Torrisi) –implemented in (private) V4_26 –tests at CNMCA / MCH / ARPA-SIM (WG7) Pattern Generator (for random fields with prescribed correlation scales) (Tsyrulnikov et al.) –based on a stochastic partial differential equation approach –basic version developed, being revised to make it efficient –being embedded in COSMO code –2-D version planned for next year

8. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 8 high-resolution obs radar –obs operators finished, assimilation works technically –radial winds v r in LETKF: Yuefei Zeng (DWD, until summer 2014)  need to test thinning / superobbing strategies  3-hour assimilation with 1-hrly cycle done (different localization radii) –v r + reflectivity Z in LETKF: Theresa Bick (HErZ-I Bonn, until end 2014 at least) GPS slant path delay –obs operator (incl. TL / adjoint) implemented in 3DVar, approximations tested –implementation in COSMO should start soon

9. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 9 high-resolution obs (SEVIRI-based, radiosonde-corrected) cloud top height : see next slides (Schomburg) new task: microwave radiometer & Raman lidar T-, q- profiles (Haefele, MCH) direct assimilation of SEVIRI radiances (window channels for cloud info) (Perianez) –technically implemented (obs operator (RTTOV), reading / writing) –work on monitoring / assimilation start in Nov.

10. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 10 avoid too strong penalizing of members with high humidity but no cloud avoid strong penalizing of members which are dry at CTH obs but have a cloud or even only high humidity close to CTH obs  search in a vertical range  h max around CTH obs for a ‘best fitting’ model level k, i.e. with minimum ‘distance’ d: Z [km] RH [%] CTH obs function of relative humidity height of model level k = 1 use f (RH obs =1) – f (RH k ) and CTH obs – h k as 2 separate obs increments in LETKF if cloud observed with cloud top height CTH obs, what is the appropriate type of obs increment ? (if above a layer with cloud fraction > 70 %, then choose top of that layer) use of (SEVIRI-based) cloud top height (CTH) ‘observations’ in LETKF: method k1k1 k2k2 k3k3 k4k4 k5k5 Cloud top model profile

11. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 11 3 6 9 Z [km] „no high cloud“ „no medium cloud“ „no low cloud“ CLC assimilate cloud fraction CLC obs = 0 separately for high, medium, low clouds model equivalent: maximum CLC within vertical range type of obs increment, if no cloud observed ? use of (SEVIRI-based) cloud top height (CTH) ‘observations’ in LETKF: method model profile

12. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 12 relative humidity cloud cover cloud water cloud ice observed cloud top 3 lines on one colour indicate ensemble mean and mean +/- spread 1 analysis step, 17 Nov. 2011, 6 UTC (wintertime low stratus) vertical profiles example: missed cloud event CTH single-observation experiments

13. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 13 observed cloud top observation location example: missed cloud event specific water content [g/kg] relative humidity [%] cross section of analysis increments for ensemble mean CTH single-observation experiments

14. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 14 CTH single-observation experiments temperature profile (mean +/- spread) example: missed cloud event first guess analysis 1000 m 2000 m 3000 m observed cloud top  LETKF introduces inversion due to RH(CTH)  T cross correlations in first guess ensemble perturbations 270 K280 K290 K270 K280 K290 K

15. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 15 relative humidity cloud cover cloud water cloud ice observed cloud top 3 lines on one colour indicate ensemble mean and mean +/- spread vertical profiles example: false alarm cloud  assimilated quantity: cloud fraction (= 0) CTH single-observation experiments

16. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 16 high cloud cover [octas] FG ANA  LETKF decreases erroneous cloud cover despite very non-Gaussian distributions mid-level cloud cover [octas] FG ANA example: false alarm cloud  assimilated quantity: cloud fraction (= 0) FG ANA low cloud cover [octas] cover CTH single-observation experiments observation increments - histogram over ensemble members

17. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 17 0:00 UTC 6:00 UTC 12:00 UTC 17:00 UTC cycled assimilation of dense CTH obs observed cloud top height (CTH) 1-hourly cycle over 21 hours, 13 Nov., 21 UTC – 14 Nov. 2011, 18 UTC (wintertime low stratus)

18. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 18 0:00 UTC 6:00 UTC 12:00 UTC 17:00 UTC cycled assimilation of dense CTH obs : LETKF setup thinning: use obs at every 5 th grid pt. adaptive covariance inflation, adaptive localisation scale (  ~ 35 km) Observation error variances : relative humidity = 10 % cloud cover = 3.2 octa cloud top height [m] : 

19. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 19 cycled assimilation of dense CTH obs RMSE spread time series of first guess errors of ensemble mean / spread of ensemble averaged over cloudy obs locations averaged over cloud-free obs locations  underdispersive, but no trend for reduction of spread

20. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 20 RMSE bias time series of first guess errors of RH at observed CTH (det. run), averaged over cloudy obs locations cycled assimilation of dense CTH obs no assimilation with cloud assimilation  CTH assimilation : reduces RH (1-hour forecast) errors

21. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 21 RMSE bias time series of first guess errors of RH at observed CTH (det. run), averaged over cloudy obs locations cycled assimilation of dense CTH obs no assimilation with cloud assimilation  CTH assimilation : reduces RH (1-hour forecast) errors assimilation of conventional obs only assimilation of conventional + cloud obs localization scale: adaptive / 20 km

22. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 22 cycled assimilation of dense CTH obs time series of first guess errors, averaged over cloud-free obs locations (errors are due to false alarm cloud) mean square error of cloud fraction [octas]  error reduced (almost) everywhere

23. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 23 No assim no assimilation cloud assimilation conventional onlyconventional + cloud total cloud cover of first guess fields after 20 hours of cycling CTH obs satellite obs cycled assimilation of dense CTH obs

24. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 24 Summary assimilation of CTH by LETKF reduces errors of first guess (1-h forecast) tends to introduce humidity / cloud where it should (+ temperature inversion) tends to reduce ‘false-alarm’ clouds despite non-Gaussian pdf’s no sign of filter collapse (decrease of spread) next: evaluate forecast impact use of (SEVIRI-based) cloud top height (CTH) ‘observations’ in LETKF

25. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 25 Thank you for your attention Questions ? Status of PP KENDA

26. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 26 LETKF: implementation GMECOSMO ensemble members40 + 1 (3DVar)40 + 1 (det. Run) horiz. resolution (ens.)~ 60 km (ni128)2.8 km horiz. resolution (det.)~ 30 km (ni256)2.8 km vertical localis. length scale (ln p)0.3 (fut.: 0.075 - 0.5)0.3 ; 0.075 – 0.5 horiz. localisation length scale300 km100 km adaptive horiz. localisation- (not used)used in latest exp. additive covariance inflation3DVar - B- adaptive multiplicative cov. infl.yes conventional obsyes satellite radiancesAMSU-A- GPS-ROnew exps- radar data-passive update frequency3 h1 h (  30 / 15 min)

27. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 27 LETKF: implementation multistep analysis (batch assimilation) implemented  motivation: local / nonlocal observations (e.g. radiances) different observation errors  better use different localization scales in view of adaptive localization: different obs densities (conventional / radar) (Perianez et al.: work on paper with theoretical concept + toy model/ idealised experiments) next step: test with radar / SEVIRI CTH data Hendrik: new flexible stand-alone scripts to run LETKF experiments without using NUMEX / archive  very limited disk space  1 real day for 1 day of LETKF assimilation to do: implement evaluation / verification tools in script suite may become very suitable tool for users outside DWD (academia)

28. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 28 low clouds mid-level clouds high clouds cycled assimilation of dense CTH obs ‘false alarm’ cloud cover (after 20 hrs cycling) conventional + cloud conventional obs only

29. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 29 Low cloud cover (COSMO) PBPV – 03/2013 29 17:00 UTC Cloud assim conv Cloud +conv No assim