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Development of the deterministic forecast system (June 2006)

Development of the deterministic forecast system (June 2006). Martin Miller (Head of Model Division) with input from many colleagues. Operational changes from June 2004 up to June 2005 (the last User Meeting). 29 June 2004 – Early Delivery System 28 September 2004 – IFS cycle 28r3

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Development of the deterministic forecast system (June 2006)

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  1. Development of the deterministic forecast system (June 2006) Martin Miller (Head of Model Division) with input from many colleagues

  2. Operational changesfrom June 2004 up to June 2005(the last User Meeting) • 29 June 2004 – Early Delivery System • 28 September 2004 – IFS cycle 28r3 • 18 October 2004 – IFS cycle 28r4 • 5 April 2005 – IFS cycle 29r1 • 28 June 2005 – IFS cycle 29r2 (examples) Anomaly correlation of 500hPa forecasts for Europe Mean from 1 Dec 2004 to 28 June 2005 Cycle 29r2 Cycle 29r1 Day

  3. Hurricane Charley Track forecasts from 12 UTC 11 Aug 2004 Comparison of cycle 29r2 e-suite and operations with independent TCWV retrievals from Jason microwave radiometer e-suite ops Global 1.74 1.90 N. Hemisphere 1.63 1.71 Tropics 2.12 2.43 S. Hemisphere 1.53 1.62 N. Atlantic 1.63 1.69 N. Pacific 1.57 1.69 St.dev(kg/m2) Rain Asm Assimilation of rain-affected microwave radiances and improvement of humidity analysis

  4. Bias-correction of surface-pressure observations December 2004 April 2005 Altamera, Brazil

  5. Use of Baltic Sea Ice Analysis from SMHI Mean sea-ice concentration 5 - 24 January 2004 NCEP analysis Local analysis

  6. Also included : • Refinements to use of ATOVS and AIRS • Improved use of TEMP and SYNOP humidity observations • Lower surface-pressure observation errors for automatic stations • Use of Meteosat-8 (MSG) winds • Statistics for Wavelet Jb from new ensemble data assimilation • Small revisions to surface, convection and cloud schemes • Better vertical diffusion in first minimization of 4D-Var

  7. 1 February 2006 – IFS cycle 30r1 • T799 horizontal resolution for deterministic forecast • 4D-Var increments at T255 (30min time step) - Use of grid-point humidity and ozone - Revised ozone chemistry • 91-level vertical resolution • Changes to the wave model • Grid spacing reduced from 0.5° to 0.36° • Use of Jason altimeter wave height data and ENVISAT ASAR spectra in the wave model assimilation • T399 L62 resolution for EPS • Wave model grid unchanged at 1°, but number of frequencies increased from 25 to 30, and number of directions from 12 to 24

  8. T799 orog

  9. T799 gridGlobe has 843,490 points(348,528 for the T511 grid)Resolution ~25km

  10. 0.01hPa 0.1hPa Position of levels and pressure layer thickness of L60 (blue) and L91 (red) L91 L60 Vertical Resolution Increase • The number of vertical levels for analysis and deterministic model increased from 60 to 91. • Largest resolution increase near the tropopause • Model top raised from 0.1hPa (~65km) to 0.01hPa (~80km).

  11. Fit to Aircraft data: V-wind in NH extra-tropics

  12. Fit to Radiosonde Data:U-Wind in the Tropics

  13. Statistical significance (t-test) for Z 500hPa scores from 304 forecast Green numbers: T799L91 better than T511L60,red numbers: T799L91 is worse

  14. 00UTC 12 December 2005: Pmsl and 10m windspeed T799L91 D+4 D+3 D+5 Analysis D+5 Analysis D+3 D+4 Operations

  15. 00UTC 9 January 2005: Pmsl and 10m windspeed T799L91 Analysis D+2 D+3 D+4 D+4 Analysis D+3 D+2 Operations

  16. Forecasts of Katrina for 12 UTC, Monday 29 August + + 36h forecast Operational T511 L60 Test T799 L91 + + 72h forecast Operational T511 L60 Test T799 L91

  17. Hurricane Katrina in operations and e-suite: t+72h e-suite T799 opsT511

  18. 26th 00UTC 3.5 days 26th 12UTC 27th 00UTC 2.5 days

  19. Remarks This upgraded forecasting system provides: • more accurate analyses and forecasts leading to better medium-range forecast guidance from both the deterministic and ensemble prediction systems • improved input to limited area forecasting in the Member States • more skilful forecasts of most types of severe weather • a better (more accurate) system on which to base research and development to further the expectations of the ECMWF longer-term strategy

  20. 7 February 2006 – New radiance bias correction Applied statically, but derived from variational scheme to be implemented with cycle 31r1 Sonde-bg Control Sonde-bg New bias correction Sonde-an Control Sonde-an New bias correction RMS error of 300hPa tropical temperature forecasts Control pressure (hPa) New bias correction N Hem Mean from 8-31 Jan 2006 Day Temperature (K)

  21. Coming next – IFS cycle 31r1 (Aug 2006) • Variational radiance bias correction • Thinning of low-level AMDAR data • Revisions to the 1D and 4D-Var rain assimilation • Improved treatment of ice sedimentation, auto-conversion to snow in cloud scheme and super-saturation with respect to ice • Implicit treatment of convective transports

  22. IFS cycle 31r1 continued (Aug 2006) • Introduction of turbulent orographic drag scheme • Includes changes for EPS extension to day 15 • T255 perturbed forecasts from day 10 to day 15 • T399/255 control to day 10/15 • Also uniform T399 and T255 controls to day 15 • To be used in version 3 of Seasonal Forecasting System • Also for the Interim reanalysis (1989 onwards)

  23. Simple ECMWF scheme: comparison to Mozaic aircraft data(from Gierens et al.) Aircraft data New scheme Default

  24. Impact on relative humidity (RH) climatology 31r1 – 30r1 annual mean difference Largest changes in the tropical upper troposphere

  25. CY31R1: New vegetation roughness + turbulent orographic form drag scheme (TOFD) Examples of orographic spectra from 100m data over the USA • Vegetation roughness from correspondence table linked to dominant land use type (Mahfouf et al. 1995) • Scales of interest are below 5 km • Use most recent 1 km orographic data • Wood and Mason (1993) parametrization for surface drag • Drag distribution over model levels rather than effective roughness length concept (Wood, Brown and Hewer, 2001) • Parametrize orographic scales from 5 km to the smallest scales as an integral over an empirical orographic spectrum (Beljaars et al. 2004 Measure spectral amplitude from 1 km data. Extrapolate spectrum by making assumption about power law.

  26. Impact of TOFD + new roughness lengths Smaller drag coefficients: diff stress/wind(level48)^2 Higher 10m wind

  27. Revised numerics of gust parametrization only (CY31R1) Old New Without stochastic physics With stochastic physics

  28. Old (CY30R1) Mean gust averaged over 14 days: gust from 24-36 hour forecasts verifying at 0-12 UTC New-Old New (CY31R1)

  29. Observed gusts versus model gusts (12 to 24 hour forecasts) Old (CY30R1) New (CY31R1)

  30. CY31R1: only non-blocked part of subgrid orography excites gravity waves (cutoff mountain) Only this height is used to excite gravity waves. Lott and Miller 1997

  31. Impact of cutoff mountain in subgrid orography parametrization Error: FC-AN Old T511 average vertically integrated zonal wind error from 96h CY29R1 forecasts from 12Z on each day of January 2005 using the new turbulent orographic drag scheme and cutoff mountain. Diff: FC_new-FC_old Error: FC-AN New

  32. 1d+4d-Var Rain Assimilation Modifications proposed for CY31R1: • Inclusion of 10m-wind speed in 1D-Var control vector: x = (t, q, u10, v10) • Revised q/c and replacement of ESSL routines for (B) Eigenvector calculations • DMSP satellite specific bias correction; more predictors (TCWV, SST, SWS, RWP) • Screening of areas with excessive frozen precipitation (mainly SH) 1D-Var Performance Mean TCWV Increments Mean TCWV Increments CY30R2 CY31R1

  33. 48-hour Forecast RMSE Difference CY31R1-CY30R2 Relative humidity Temperature >0: CY30R2 better <0: CY31R1 better (August 2005, T511L60)

  34. Also planned for later in 2006: • Use of surface albedo fields from MODIS • Use of high-resolution NCEP SST fields • Refinements to stratospheric analysis • Recalibrated radiosonde temperature bias corrections • Unified medium-range/monthly EPS

  35. And possibly at the end of 2006: • 4D-Var changes: • 3rd inner loop • revised trajectory interpolation • revised data usage, including modified Var QC • new cloud and convection schemes in minimization • Upgrade fast radiative transfer to RTTOV-9 • Change model short-wave radiation scheme to RRTM-SW • Upgrades to ocean wave advection and assimilation And over course of the year: • Monitoring and later assimilation of data from: • AMSR-E, CHAMP, COSMIC, FY-2C, METOP ATOVS + … , MET9, MTSAT, SSMIS, TMI

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