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MMB Operations / Parallels Briefing

MMB Operations / Parallels Briefing. 7 October 2004. High-Resolution Window Domains (colored) nested in Eta Domain (black). Primary mission of High- Resolution Window (HIRESW) run is to provide forecaster guidance for severe weather. Forecast length: 48 h Frequency: Once per day for

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MMB Operations / Parallels Briefing

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  1. MMB Operations / Parallels Briefing 7 October 2004

  2. High-Resolution Window Domains (colored) nested in Eta Domain (black) Primary mission of High- Resolution Window (HIRESW) run is to provide forecaster guidance for severe weather. Forecast length: 48 h Frequency: Once per day for CONUS and Alaska domains; Twice per day for Hawaii (00z/12z) and Puerto Rico (06z/18z). Initial/boundary conditions from operational Eta 00Z 18Z 06Z 12Z

  3. Operational implementation • 21 September 2004 : Replace single run of NCEP Non-hydrostatic Meso Model (NMM) in the HiResWindow suite with two runs • The WRF version of the NMM (WRF-NMM) • The WRF version of the Eulerian Mass core (WRF-EM) with physics chosen by NCAR http://wwwt.emc.ncep.noaa.gov/mmb/mmbpll/nestpage

  4. Changes to NMM dynamics • The Matsuno vertical advection scheme has been replaced with the neutral, unconditionally stable Crank-Nicholson scheme • The Smagorinsky constant in the lateral diffusion is reduced by 70% • The effect of horizontal shear of vertical velocity has been added to the lateral diffusion scheme. • The fundamental time step has been reduced by 10%.

  5. Changes to NMM Physics • Input data on surface conditions (soil and vegetation type) have been refined • Soil heat capacity has been increased which results in larger ground fluxes • The dependence of roughness length (z0) on the height of topography has been removed, significantly reducing z0 over elevated terrain • The countergradient heat flux has been added to the turbulent kinetic energy (TKE) equation and in the vertical heat diffusion • The diagnostic mixing length has been increased • The floor values for TKE and mixing length have been significantly reduced • Increased residual turbulent mixing has been introduced in case of strong stability between the top of the surface layer and the layer above the inversion • The effect of entrainment has been incorporated into the procedure for finding convective cloud top pressure. • The entropy change threshold for triggering deep convection has been reduced

  6. Interaction With GFDL Hurricane Runs • No Hurricanes • Full Set Runs – Two Large and Two Small WRF Domains • One Hurricane • Eliminate Small WRF-NMM and WRF-EM Domains • Two Hurricanes • Eliminate Large WRF-EM Domain • Three Hurricanes • Eliminate Large WRF-NMM and WRF-EM Domains • Four Hurricanes • No WRF Runs • EMC will run any cancelled NMM run on dev machine • EMC will not rerun cancelled EM forecasts due to resource limitations

  7. 24 Hour Accumulated Precipitation Valid 12Z 6 September, 2004, 42 Hour Forecast OPS. NMM WRF NMM CPC RFC 1/8 deg Verification Tropical Storm Frances: Subjective Comparison OPS. Eta WRF EM

  8. Hurricane Francis passing through Puerto Rico HIRESW domain : 31 August – 1 September

  9. Implementation Strategy : 6-member HIRESW Ensemble • When : 2nd Quarter 2005 (EMC) or 3rd Quarter 2005 (NCO) • Six-member WRF ensemble will run four times daily, once for each • of 6 HIRESW domains. • - 2 controls (WRF-NMM, WRF-EM, now running in ops) • - 4 additional members with bred perturbations in ICs/BCs • 80-min run window (clock time) shared with GFDL Hurricane model. • Availability of two control members guaranteed. • Availability of additional members contingent on number of tropical storms. • Ensemble feasible following CCS Phase 2 upgrade of NCEP computers. 

  10. What has been tested: 32 km parallels • Probable / Likely / Possible components • 3DVAR changes (NEXRAD level 2.5 radial winds; 2dvar analysis of sfc temperature data • “Scaled-back” precipitation assimilation (eliminate/simplify increase and/or creation of latent heat) • Version 2.7 of Noah LSM with hi-res soil/veg types • GFS radiation physics and changes to cloud cover formulations • Components no longer under consideration • Modified shallow convection parameterization • Gory details for parallels ETAY, ETAZ, ETAL, ETAW at http://wwwt.emc.ncep.noaa.gov/mmb/mmbpll/paralog

  11. Analysis of surface data in Eta 3DVAR • NCEP's Manuel Pondeca has developed a two dimensional data assimilation module, with the goal of improving the analysis of surface observations within the Eta 3DVAR system (sfc land temps removed from ops EDAS in September 2003 due to adverse impact on lower/mid tropospheric analysis) • In the 2DVAR module, the analysis is univariate and the background error correlations may be chosen to be anisotropic functions that stretch along the contour lines of the terrain field to some degree. • Applied to entire domain after 3DVAR analysis, 2DVAR increments on lowest Eta mmodel surface replace those from original 3DVAR analysis • Impact is small

  12. RMS Temp RMS wind Bias Temp RMS Z 12-h forecasts 13-22 Sept 2004

  13. Assimilation of Level 2.5 NEXRAD Radial winds : 32-km parallel ran 4-28 June 2004

  14. RMS Temp RMS Wind RMS Height Bias Temp 12-h forecasts 4-28 June 2004

  15. RMS Wind RMS Temp RMS Height Bias Temp 48-h forecasts 4-28 June 2004

  16. Why is this the Final Eta change package?? • North America Meso (NAM) with WRF-NMM scheduled to replace Eta in 4th quarter of 2005 • Finalize Eta bundle now to start 12km parallel on new dev machine (which will be a full-blown 4x/day parallel w/DGEX) • Begin transition / development of NAM Data Assimilation System (NDAS) with GSI analysis

  17. Proposed Timeline - 1 November : Finalize choice of components to Eta change package; begin 4 cycles/day 12km parallel on new dev machine with DGEX • 1 November – 31 December : Closely monitor performance and pray • 15 November : Write draft charter for NCO • 31 January 2005 (?) Try to get NCO the codes so they can start implementation process as soon as CCS upgrade is operational • 31 March 2005 ( at the absolute latest) Plan for 2nd quarter 2005 implementation

  18. Real-time runs at http://wwwt.emc.ncep.noaa.gov/mmb/mmbpll/etapll32 http://wwwt.emc.ncep.noaa.gov/mmb/mmbpll/etapll32.etaw or

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