1 / 23

First Results from SLEPS

First Results from SLEPS. A. Walser, M. Arpagaus, C. Appenzeller, J. Quiby MeteoS wiss. SLEPS. SLEPS: Short-range limited-area ensemble prediction system. Within project ‘Extreme Events’ of the Swiss national research project NCCR.

norina
Download Presentation

First Results from SLEPS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. First Results from SLEPS A. Walser, M. Arpagaus, C. Appenzeller, J. Quiby MeteoSwiss

  2. SLEPS • SLEPS: Short-range limited-area ensemble prediction system. • Within project ‘Extreme Events’ of the Swiss national research project NCCR. • Strategy bases on an adapted COSMO-LEPS for the short-range. • Should be considered as a first step towards a short-range EPS. • The smaller scales resolved in SLEPS implies the consideration of alternative growth mechanisms beyond the baroclinic growth accounted for by the SV analysis.  Strategies for the definition of optimal small-scale perturbations have to be found. Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen

  3. 12 n+2 12 n-1 12 n 12 n+1 12 n+3 12 n+4 12 n+5 00 00 00 00 00 00 day: SLEPS: Short-range adaptation of COSMO-LEPS Start of COSMO-LEPS integrations short-range clustering times COSMO-LEPS clustering times moist? EPS number of RMs? moist? EPS ? members horizontal resolution? moist? EPS Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen

  4. SLEPS: current setup Global ECMWF EPS ensembles with moist singular vectors 50+1 members Hierarchical Cluster Analysis area: Europe fields: 4 variables (U,V,Q,Z) at 3 levels (500, 700, 850) for 3 time steps (24h, 48h, 72 h), number of clusters: fixed to 5 5 clusters Representative Member Selection one per cluster: member nearest (3D) to the mean of its own cluster AND most distant to the other clusters’ means Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen 5 representative members (RMs) 5 Lokal Modell (limited-area) integrations nested into 5 RMs SLEPS: Short-range limited-area Ensemble Prediction System

  5. SLEPS: model domain with topography 10 km mesh-size horizontally, 32 vertical levels. Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen

  6. Moist vs. operational singular vectorsCoutinho et al. (2003) • ‚opr‘ SVs (T42L31, OTI 48 h): linearized physics package with • surface drag • simple vertical diffusion • ‚moist‘ SVs (T63L31, OTI 24 h): linearized physics package includes additionally: • gravity wave drag • long-wave radiation • deep cumulus convection • large-scale condensation  moist SVs: use of moist processes during SV evolution, but same norm (‚total energy norm‘)  no humidity perturbations. Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen

  7. 2 case studies: • Storm Lothar (“Christmas Storm”): 26 December 1999 • moist SV ECMWF EPS SLEPS 19991224 00 UTC, + 72 h • opr SV ECMWF EPS  SLEPS 19991224 00 UTC, + 72 h • Storm Martin: 27/28 December 1999 • moist SV EPS ECMWF SLEPS 19991226 00 UTC, + 72 h • opr SV EPS ECMWF  SLEPS 19991226 00 UTC, + 72 h Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen

  8. RMSENS [m] Forecast time [h] Mean RMS error Z@850 hPa of ECMWF EPS to opr analysis in SLEPS domain y: predicted value o: values of analysis N: number of members I: number of grid points red: opr SVs EPS blue: moist SVs EPS solid: Storm Lothar dotted: Storm Martin Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen

  9. Lothar Storm Lothar: probability forecast of SLEPS for 10 m wind gusts opr SVs moist SVs ECMWF opr analysis Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen

  10. Lothar: 6 hours later… opr SVs moist SVs opr SVs Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen

  11. Lothar: again 6 hours later… moist SVs opr SVs Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen

  12. Lothar: again 6 hours later… moist SVs opr SVs Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen

  13. Lothar: probability forecast for 10 m wind gusts over the 24 hours storm period moist SVs opr SVs Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen • Both ensemble quite similar. • Moist SVs SLEPS predicts a higher risk for strong wind gusts over northern France.

  14. Lothar: ECMWF EPS using only LEPS representative members over the 24 hours storm period moist SVs opr SVs Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen Rather reduced probabilities compared to SLEPS in particular over the Atlantic. SLEPS downscaling seems to be beneficial in this case.

  15. Lothar: ECMWF EPS using all 51 members over the 24 hours storm period opr SVs moist SVs Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen Very similar  Effect of moist SVs not obvious.

  16. Martin Storm Martin: probability forecast of SLEPS for 10 m wind gusts moist SVs opr SVs Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen

  17. Storm Martin: 6 hours later… moist SVs opr SVs Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen

  18. Storm Martin: 6 hours later… moist SVs opr SVs Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen

  19. Storm Martin: 6 hours later… moist SVs opr SVs Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen

  20. Storm Martin: probability forecast for 10 m wind gusts over the 24 hours storm period moist SVs opr SVs Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen • moist SVs SLEPS predicts a risk in south-western France and northern Mediterranean Sea. • opr SVs SLEPS misses the storm.

  21. Martin: ECMWF EPS using only LEPS RMsover the 24 hours storm period moist SVs opr SVs Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen • Provided risk from moist SVs ECMWF EPS lower over southwestern France and northern Mediterranean sea. • Opr SVs ECMWF EPS also misses the storm.

  22. Martin: ECMWF EPS using all 51 members over the 24 hours storm period moist SVs opr SVs Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen Using all EPS members, differences between moist and opr SVs EPS smaller  moist SVs SLEPS additionally favoured by the clustering procedure.

  23. Conclusions from first SLEPS simulations • Wind gust prediction for storm Lothar: • Effect of moist SVs in SLEPS and ECMWF EPS small. • Downscaling effect with SLEPS beneficial but not crucial. • Wind gust prediction for storm Martin: • Effect of moist SVs clearly positive both in SLEPS and ECMWF EPS. • opr SVs SLEPS does not provide a storm warning. • Downscaling effect with moist SVs SLEPS beneficial. Andre.Walser@MeteoSwiss.ch COSMO General Meeting, 2003, Langen

More Related