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 experiment for June 2011 lateral BC by direct interpolation from 60 km to 2.8 km KENDA: –1-hourly cycling, radiosonde, aircraft, wind profiler, synop –40 ensemble members, basic set-up (only adaptive cov. infl.) –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

3. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 3 LETKF: implementation other work: adaptive estimation of observation errors in observation space multi-step analysis implemented compare KENDA ensemble forecasts with COSMO-DE-EPS (8 days) at MCH / ARPA-SIM : studies on influence of different lateral BC (resolution gap) at MCH: compare determinstic LETKF analysis with nudging ana. (7 days) 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)

4. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 4 Impact of lateral BC resolution Marsigli, Paccagnella, Montani: Test impact of lateral BC resolution for convection-permitting EPS 8 cases from Hymex SOP: 6 Sept. – 5 Nov. 2012 COSMO-H2-EPS set-up (‘H2-CLEPS’): 2.8 km, 50 levels 10 members IC + BC COSMO-LEPS, res. 7 km run at 12 UTC 36h forecast range exp. ‘H2-IFS’: direct nesting IC and BC from IFS-EPS res: 0.25 °

5. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 5 mean difference between pairs of ensemble members < spread < rmse (i.e. e.g. betw. Member 1 of H2-CLEPS and Member 1 of H2-IFS) 1 exceptional case spin-up noise dies within 30 min impact on precip scores negligible 500 hPa geopotential Impact of lateral BC resolution

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:make clean interfaces to observation operators in COSMO … … integrate them into 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 testing KENDA at MCH, ARPA-SIM OSSE –temperature inversion in Po Valley: assimilate synthetic TEMP –(semi-)idealised: horizontally homogeneous case; daily cycle of Alpine pumping  develop OSSE capability  COSMO reading feedback files implemented no PhD project on idealised OSSE to investigate convective-scale issues

8. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 8 accounting for model error stochastic perturbation of physics tendencies (SPPT) (Torrisi) –perturbation of moist turbulence tendencies implemented –implemented in (private) V4_26 –tests (LETKF for COSMO-ME): drying effect on precip –further tests in MCH / ARPA-SIM Pattern Generator (for random fields with prescribed correlation scales) (Tsyrulnikov et al.)

9. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 9 high-resolution obs radar –obs operators finished –radial winds v r in LETKF: Yuefei Zeng (DWD, until summer 2014)  monitoring of 3d volumn data (statistics of observation increments) : large scatter, data quality problems  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

10. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 10 high-resolution obs (SEVIRI-based, radiosonde-corrected) cloud top height : see next slides (Schomburg) new task: Raman lidar and microwave radiometer 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.

11. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 11 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] Cloud top 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

12. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 12 3 6 9 Z [km] „no cloud“ CLC assimilate cloud fraction CLC = 0 separately for high, medium, low clouds model equivalent: maximum CLC within vertical range type of obs increment, if no cloud observed ? 3 6 9 12 Z [km] - no data - „no cloud“ Cloud top model profile use of (SEVIRI-based) cloud top height (CTH) ‘observations’ in LETKF: method

13. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 13 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

14. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 14 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

15. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 15 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

16. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 16 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

17. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 17 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

18. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 18 example: false alarm cloud  assimilated quantity: cloud fraction (= 0) FG ANA low cloud cover [octas]mid-level cloud cover [octas]high cloud cover [octas] cover CTH single-observation experiments observation increments - histogram over ensemble members FG ANA FG ANA  LETKF decreases erroneous cloud cover despite very non-Gaussian distributions

19. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 19 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)

20. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 20 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] : 

21. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 21 cycled assimilation of dense CTH obs FG ANA RMSE bias  analysis error smaller than first guess (FG) errors time series of errors for deterministic run, averaged over cloudy obs locations ‘CTH’  CTH obs  height k ‘RH’  1 - RH k (k : ‘best fitting model level’) ‘RH at obslev’ (i.e. at observed CTH)

22. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 22 cycled assimilation of dense CTH obs RMSE spread time series of 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

23. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 23 RMSE bias time series of first guess errors (det. run), averaged over cloudy obs locations cycled assimilation of dense CTH obs no assimilation with cloud assimilation  CTH assimilation : hardly reduces height error of selected level k reduces RH (1-hour forecast) errors ‘RH at obslev’

24. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 24 cycled assimilation of dense CTH obs RH at obslev RMSE bias no assimilation with cloud assimilation  CTH assimilation : reduces RH errors related to low + mid-level cloud time series of first guess errors, averaged over cloudy obs locations

25. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 25 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]

26. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 26 low clouds mid-level clouds high clouds cycled assimilation of dense CTH obs ‘false alarm’ cloud cover (after 6 hrs cycling) with cloud assimilation no assimilation

27. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 27 time series of first guess errors, averaged over cloudy obs locations cycled assimilation of dense CTH obs assimilation of conventional obs only assimilation of conventional + cloud obs localization scale: adaptive / 20 km RMSE bias  CTH assimilation : reduces RH (1-hour forecast) errors even slightly reduces height error of selected level k

28. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 28 no assimilation RH at obslev cycled assimilation of dense CTH obs first guess fields after 20 hours of cycling (cloudy obs locations) CTH obs cloud assimilation conventional onlyconventional + cloud

29. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 29 PBPV – 03/2013 29 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

30. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 30 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

31. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 31 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

32. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 32 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

33. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 33

34. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 34 with cloud assimilation no assimilation ‘ CTH‘ OBS-FG RH RH at obslev cycled assimilation of dense CTH obs first guess fields after 20 hours of cycling (cloudy obs locations) CTH obs

35. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 35 Low cloud cover (COSMO) PBPV – 03/2013 35 17:00 UTC Cloud assim conv Cloud +conv No assim

36. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 36 RMSE and bias for different heights separately: Cloud assim. vs. no assim. RH@oblse v

37. christoph.schraff@dwd.de Status of PP KENDA COSMO General Meeting, Sibiu, 2 – 5 Sept. 2013 37 LETKF: validation of forecasts from KENDA COSMO-DE EPS EPS on KENDA intermediate combined