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Status Report for KENDA-O

Status Report for KENDA-O. Christoph Schraff Deutscher Wetterdienst, Offenbach, Germany. Contributions / input by: Hendrik Reich, Andreas Rhodin, Roland Potthast, Klaus Stephan, Ulrich Blahak, Michael Bender, Elisabeth Bauernschubert, Axel Hutt, … (DWD)

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Status Report for KENDA-O

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  1. Status Report for KENDA-O Christoph SchraffDeutscher Wetterdienst, Offenbach, Germany Contributions / input by: Hendrik Reich, Andreas Rhodin, Roland Potthast, Klaus Stephan, Ulrich Blahak, Michael Bender, Elisabeth Bauernschubert, Axel Hutt, … (DWD) Daniel Leuenberger, Alexander Haefele (MeteoSwiss); Sylvain Robert (ETH) Chiara Marsigli, Virginia Poli, Tiziana Paccagnella, Thomas Gastaldo (ARPA-SIM) Lucio Torrisi, Francesca Marcucci, Valerio Cardinali (COMET) Mikhail Tsyrulnikov, Dmitri Gayfulin (HMC) KENDA: Km-scale ENsemble Data Assimilation • Introduction / motivation • Status / progress / results on operationalization • Status of other tasks, incl. high-resolution observations

  2. KENDA, Motivation : Why develop Ensemble Data Assimilation (EnDA) ? COSMO-DE (x = 2.8 km, ~ 1200 x 1300 km) deep convection simulated explicitly convection-permitting NWP: stochastic nature of (air-mass) convection • deliver probabilistic (pdf) rather than deterministic forecast • focus on ensemble prediction system (EPS) current EPS (COSMO-DE EPS) without DA cycle • develop ensemble DA • to provide suitable perturbed IC for EPS

  3. Whitaker et al., 2005 Motivation : Why develop Ensemble Kalman Filter (EnKF) ? analysis increments given a single observation • EnDA / EnKF : uses first guess (1h forecast) ensemble to estimate current, flow-dependent first guess errors + use  ensemble spread mainly localised over frontal area, + fcst. errors assumed in EnKF  observation causes analysis increments over frontal area • advantage esp. in convective scale, where error covariancesstrongly flow dependent

  4. Motivation : Why develop EnKF / LETKF ? • provide perturbed IC for EPS • improved analysis / forecast quality by use of • multi-variate, flow-dependent error covariances • better suitable than current/previous operational nudging scheme for use of • indirect observations (satellite, radar, etc.): • nudging requires retrievals (e.g. T-, q- profiles from satellite radiances) • EnKF: apply forward observation operator ( simulated radiances)  Local Ensemble Transform Kalman Filter (LETKF, Hunt et al. 2007) , (because of its relatively low computational costs) developed in COSMO priority project: Km-scale ENsemble DA (KENDA)

  5. KENDA-LETKF: (pre-) operational setup, incl. deterministic analysis / forecast  KENDA: 4D-LETKF + LHN (latent heat nudging for assimilation of radar precip) benchmark: operational EPS (40 mem.)  K: Kalman Gain for ensemble mean benchmark: oper. Nudging (unperturbed) (pre-) operational settings: • conventional obs types only (radiosonde, aircraft, wind profiler, synop) • adaptive horizontal localisation(keep # obs constant, 50 km ≤ s ≈ std dev ≤ 100 km) • adaptive mutliplicative covariance inflation (obs-f.g. statistics) + RTPP (p = 0.75) • explicit soil moisture perturbations (only DWD), … 1 hour 1 hour

  6. KENDA-O overview • PP KENDA-O : Km-Scale Ensemble-Based Data Assimilation • for the use of High-Resolution Observations • (Sept. 2015 – Aug. 2020) • Task 1: further development of LETKF scheme • mainly with conventional obs only • includes work towards operationalization • Task 2: extended use of observations • high-resolution, moisture-related: radar, satellite all-sky (cloud), GPS • other: screen-level, Mode-S aircraft, ground-based remote sensing, etc. • Task 3: lower boundary: soil moisture analysis using satellite soil moisture data • Task 4: adaptation to ICON-LAM, hybrid methods (also particle filters)

  7. (pre-)operational use of KENDA • MeteoSwiss: KENDAoperational for EPS • (COSMO-E : x = 2.2km) • since 19 May 2016 • (KENDA for det. COSMO-1: 2017 • (T,qv in PBL still worse, lack of spread)) • DWD: KENDA run in pre-operational suite • for deterministic + EPS forecasts • with COSMO-DE (x = 2.8 km) • since May 2016 • ARPAE-SIMC: pre-operationalsuite with (Italy) KENDA-IC for 2.2 km EPS since Oct.(?) • COMET: KENDA code adapted to include • (Italy) required capabilities of COMET system • and run in a parallel suite (x = 10 km)

  8. Task 1: Further development of KENDA, operationalisation MeteoSwiss • tests with stochastic physics (SPPT) + soil moisture perturbations (SMP) to increase ensemble spread (too low in PBL, mainly T + qv) • summer: consistent positive impact • winter: smaller positive impact on temperature, but mixed impact on humidity (to be further evaluated: 1 month statistics) • fog + low stratus: mixed feedback by forecasters, sometimes very good, sometimes very bad • operational KENDA draws the analysis (clearly) less close to the observations compared to nudging (for COSMO-1 and COSMO-7) (without SPPT, SMP)

  9. Task 1: Further development of KENDA, operationalisation : DWD DWD : summary of results from pre-operational suite in summer • deterministic (vs. nudging) • (convective) precipitation improved • surface pressure degraded, balance issue, partly due to bias in lateral BC • otherwise neutral; biases less corrected • EPS (vs. nudging + multi-model perturbations) • all variables, in particular (convective) precipitation, except surface pressure, clearly improved (errors and in particular spread, ensemble scores)  surface pressure problem: • not solved by incremental analysis update etc. • hydrostatic temperature correction greatly improves (geostrophic adjustment + ) surface pressure forecast, but degrades upper-air temperature • yet unsolved, but not critical for operationalization

  10. Task 1: pre-operational parallel suite DWD in summer: soil moisture perturbations (24 August 2016) T2m at noon, diff. betw. 2 mem. (1,8) 10 5 0 -5 -10 standard soil moisture perturb.:  T2m deviations of individual ensemble members unrealistically large in some situations 10 5 0 -5 -10 test: soil moisture perturbations reduced by 50 % :  T2m deviations realistic  to be done before summer: limit amplitude of soil moisture perturbations, possibly add soil temperature perturbations

  11. Task 1: operationalisation at DWD wintertest winter test (22 Jan. – 24 Feb. 2016) with pre-operational setup, determ. + (20-member) EPS forecasts • operational benchmark EPS: IC: nudging + multi-model, lateral BC: BCEPS • “KENDA + BCEPS”: IC: KENDA, lateral BC: BCEPS • “KENDA + ICON-EPS”: IC: KENDA, lateral BC: ICON-EPS  will become operational

  12. status KENDA: summary from winter test • deterministic: upper-air verif. neutral, precip neutral (low threshold slightly worse: pos. bias) • precipitation, EPS • KENDA: otherwise slightly positive (particularly resolution), (less spin-up  pos. bias early) • ICON-EPS BC: clear improvement (reliability / spread) • 1-hrly wind gusts, EPS (mainly 14m/s + 18m/s) • KENDA: reduces errors in first 10 hours, improved resolution • ICON-EPS BC: improved spread + reliability

  13. pre-operational KENDA (setup) vs. operational nudging: winter test (22 Jan. – 24 Feb. 2016), EPS 1-h wind gusts , 0-UTC runs RMSE KENDA + ICON-EPS operational KENDA + ICON-EPS KENDA + BCEPS spread 12 UTC similar

  14. pre-operational KENDA (setup) vs. operational nudging: winter test (22 Jan. – 24 Feb. 2016) , det. T2M RH2M PS bias KENDA nudging std.dev. rmse

  15. status KENDA: summary from winter test • precipitation, EPS • KENDA: otherwise slightly positive (particularly resolution), (less spin-up  pos. bias early) • ICON-EPS BC: clear improvement (resolution / spread) • 1-hrly wind gusts, EPS (mainly 14m/s + 18m/s) • KENDA: reduces errors in first 10 hours, improved resolution • ICON-EPS BC: improved spread + reliability • T2M(det + EPS) • KENDA: increased cold bias (by 0.4K) and increased rmse (by 0.2K) • ICON-EPS BC: improved spread + reliability • low stratus (2 cases, deterministic forecast with KENDA IC) • too little low cloud (much less than nudging) • moist layer too shallow, slightly too dry, no mixed layer below inversion  KENDA (+ ICON-EPS) not made operational end Nov. 2016

  16. status KENDA: summary from winter test • T2M • increased cold bias (by 0.3K) in KENDA • impact on soil: less ice melted in soil layer 4 (6 – 18 cm) during warm period (2 weeks) • Grib accuracy for T_SO: • when melting of soil ice, very small T_SO increase only • Grib accuracy for T_SO too small  T_SO same as in previous analysis • soil ice diagnosed from T_SO, W_SO  same as in previous analysis • melting of soil ice underestimated, more in 1-h cycling (KENDA) than 3-h cycling (nudging)

  17. pre-operational KENDA (setup) vs. operational nudging: winter test (23 Jan. – 24 Feb. 2016) , det. T2M std.dev. bias rmse Nudgingw. T_SO-corr KENDA w. T_SO-corr nudging w. T_SO (+ soilice) bug KENDA w. T_SO (+ soil ice) bug

  18. status KENDA: summary from winter test • increased Grib accuracy for T_SO, in COSMO V5.04 • additive covariance inflation • by sampling of climatological (coarse-scale) 3DVar B-matrix from global DA • amplitude as for additive inflation for global LETKF (0.25 * Bclim), doubled for humidity  Exp.: Dec. 2016 (with low stratus periods: 3. – 9., 15. – 21., 29. – 02.01.) (statistical) results: • increased spread • small effect on random errors (in upper-air verif.) • decreased bias of low-level temperature + T2M

  19. Exp 1001 (additive inflation, initial soil cond.) vs. pre-oper. KENDA surface verif. 1 – 31 Dec. 2016 additive infl. opr. nudging std. KENDA

  20. KENDA with additive inflation vs. operational nudging surface verif. 1 – 31 Dec 2016 T2M RH2M PS bias additive inflation nudging std.dev. rmse

  21. KENDA winter experiments: low cloud, 5 Dec. 2016, 12 UTC exp. 1001: additive infl. operational nudging pre-oper. KENDA 5 Dec 2016, 0 UTC + 12 h 5 Dec 2016, 12 UTC+ 0 h

  22. KENDA winter experiments: Vert. profiles, 50°/10°, 5 Dec. 2016, 12 UTC exp. 1001: additive infl. operational nudging pre-oper. KENDA T QV QC 5 Dec 2016, 12 UTC+ 0 h

  23. KENDA winter experiments: low cloud, 5 Dec. 2016, 12 UTC 5 Dec 2016, 0 UTC + 12 h operational nudging pre-oper. KENDA exp. 1001: additive infl. hits / false alarms / missed events / no data

  24. KENDA winter experiments: low cloud, 5 Dec. 2016, 0 UTC 4 Dec 2016, 12 UTC + 12 h operational nudging pre-oper. KENDA exp. 1001: additive infl. hits / false alarms / missed events / no data

  25. KENDA winter experiments: low cloud, 6 Dec. 2016, 0 UTC 5 Dec 2016, 12 UTC + 12 h operational nudging pre-oper. KENDA exp. 1001: additive infl. hits / false alarms / missed events / no data

  26. KENDA winter experiments: low cloud, 4 Dec. 2016, 12 UTC 4 Dec 2016, 0 UTC + 12 h operational nudging pre-oper. KENDA exp. 1001: additive infl. hits / false alarms / missed events / no data

  27. KENDA winter experiments: low cloud, 8 Dec. 2016, 12 UTC 31 Dec 2016, 0 UTC + 12 h operational nudging pre-oper. KENDA exp. 1001: additive infl. hits / false alarms / missed events / no data

  28. Task 1: Further development of KENDA, operationalisation : DWD low stratus: 2 periods at least as good as nudging, 1 period worse  good enough for KENDA operational in spring, but (later) try to further improve on low stratus (impact of humidity QC bug found recently?) required for operationalisation in March 2017:  test additive covariance inflation in (convective) summer period  to be done before summer: limit amplitude of soil moisture perturbations, possibly add soil temperature perturbations

  29. Progress in KENDA-O: Task 2: Extended use of observations: ongoing 3-D radar (radial velocity Vr , reflectivity Z) • Vr: Elisabeth Bauernschubert since 10/15 (IAFE-IVS) : • sensitivity tests (localisation; quality controlled data: more data used, less positive impact, not understood) • convective 2-week exp.: - TEMP/upper-air + surface verif neutral - against radar Vr: positive up to +4h - precip (0-UTC runs) improved • Uli Blahak: started fix position IVS/radar at DWD • Z: Axel Seifert: tests with LETKF at 1.1 km resolution (context IVS) • Z: Virginia Poli, Thomas Gastaldo (ARPAE-SIMC): DA with  1 Italian radars: • Mie scalttering in EMVORADO • RTPS in LETKF • next: sub-hourly DA cycle

  30. Progress in KENDA-O: Task 2: Extended use of observations GNSS slant total delay (STD, Michael Bender) • experiments: positive impact on precip so far, mixed otherwise (negative at low levels) • STD observation operator in COSMO V5.04d plans: • Q1 2017: passive monitoring of ZTD in (pre-)operational suite • Q2 2017: STD technically ready for operational use, passive monitoring (converter (ASCII / NetCDF) to BUFR  NetCDF : reader in COSMO) • 2017 - 2018: refinement of DA, impact experiments • 2018: operational introduction of STD in KENDA

  31. Progress in KENDA-O: Task 2: Extended use of observations SEVIRI radiances • direct use of all-sky (cloudy) SEVIRI WV + IR window radiances: Axel Hutt • reproducing method of Harnisch et al. 2016, QJRMS, for cloud-dependent obs errors + bias correction • investigation on transience / statistical relevance of results (huge obs errors) • technical work (ongoing): upgrade to V5.05, RTTOV-12, BACY • LMU: new PostDoc Josef Schröttle • use of NWC-SAF cloud top height (CTH) product: currently no resources • (outside KENDA-O:) direct use of all-sky (cloudy) SEVIRI VIS/NIR radiances • Lilo Bach will start at DWD March 2017 (work together with Leonard Scheck, LMU)

  32. Progress in KENDA-O: Task 2: Extended use of observations Screen-level obs • RH2M (+ T2M) : tests at DWD & MeteoSwiss (Master thesis) soon • 10-m wind : new criteria (dep on. roughness length + d2zoro/(dx2dy2)) for station selection of 10-m wind in COSMO V5.04d Mode-S aircraft • tests at DWD & MeteoSwiss soon (bug fixes in COSMO V5.04d) Ground-based remote sensing (T + qv prof.: Raman lidar, MW radiometer) • MCH: preparation for DA of LIDAR qv + T • plan (Declair): implement reader for MWR (NetCDF in hp(cp)2 template) • more generic interface for novel obs types? AMSU, ATMS, IASI • nothing done

  33. Progress in KENDA-O Task 3: Soil moisture analysis using satellite soil moisture • use of soil moisture products from HSAF based on ASCAT (+ SMOS, SMAP) • soil moisture DA (incl. QC, innovation statistics) implemented in KENDA (to be done: different grid for computing weight matrices in soil) • plan to run soil moisture DA in a parallel suite for longer period • EumetsatFellow Valerio Cardinali left, must be replaced (waiting for Eumetsat how to proceed) Task 4.2: Particle filters • Sylvain Robert (ETH), EnKPF: ongoing research • 1-week DA with PF for conv. Obs: f.g. (+1h) slightly improved over LETKF • investigation (in theory, simple cases, COSMO-KENDA) of several algorithms for adaptive choice for weight of EnKF and PF in the analysis (idea: use PF where/when useful, fall back on EnKF when distribution is more Gaussian or PF does not work for whatever reason)

  34. Progress in KENDA-O Task 4.1: KENDA for ICON-LAM, incl. EnVar • MEC-based LETKF for COSMO: ready to be tested  allows to test 4-D aspect of LETKF (only conventional obs) • MEC-based LETKF for ICON-LAM: ready to be tested (e.g. grid pt. assignment) (with COSMO obs operators) except for (hydrostatic) balancing step(s) • full 4-D LETKF for ICON-LAM: • capsulate DACE data structures, adjust e.g. parallel environment (March 17) • implement COSMO obs operator into ICON (for conventional obs: after adapting to DACE environment) • (re-write ‘cdfin’ reading routines?) • EnVar for ICON-LAM: TL + adjoint of obs operators (incl. radar etc.)

  35. This is not meant to be the end of progress in KENDA-O, but the end of this presentation

  36. additive covariance inflation using 3DVar-B (10 – 18 Feb. 2016) T T bias f.g. rmse f.g. bias ana bias ana rmse spread additive covariance inflation: • increasesf.g. spread • draws analysis closer to obs • reduces low-level T rmse in f.g. • reduces low-level T, T2M bias • little effect on forecast errors (T, wind…) RH f.g. rmse ana rmse spread

  37. Exp 1001 (additive inflation) vs. pre-oper. KENDA surface verif. 1 – 31 Dec. 2016 KENDA (additive infl.) vs. std. KENDA KENDA (additive infl.) vs. nudging RH wind dir. RH wind dir. wind speed wind speed T T

  38. Progress in KENDA-O: Task 2: Extended use of observations 1-h precip, FSS (30 km) 15 days : 25 May 12 UTC – 10 June 0 UTC, 2016 12-UTC runs 0-UTC runs Conv + LHN Conv + LHN + radar-Vr 0.1mm/h 0.1mm/h 1mm/h 1mm/h 5mm/h 5mm/h

  39. Task 1: pre-operational parallel suite DWD in summer: soil moisture perturbations (24 August 2016) soil moisture layer 5, diff. betw. 2 mem. (1,8) T2m at noon, diff. betw. 2 mem. (1,8) 10 5 0 -5 -10 standard soil moisture perturb.:  T2m deviations of individual ensemble members unrealistically large in some situations 200 100 0 -100 10 5 0 -5 -10 test: soil moisture perturbations reduced by 50 % :  T2m deviations realistic 100 50 0 -50  will implement limiter to spread of soil moisture index and assess impact on LETKF (spread)  to be done before summer: limit amplitude of soil moisture perturbations, possibly add soil temperature perturbations

  40. Exp 1001 (additive inflation, initial soil cond.) vs. pre-oper. KENDA surface verif. 1 – 31 Dec. 2016 T2M RH2M PS bias additive inflation std. KENDA std.dev. rmse

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