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Hurricane Model Transitions to Operations at NCEP/EMC

Hurricane Model Transitions to Operations at NCEP/EMC. 2009 IHC Conference, St. Petersburg, FL Robert Tuleya*, V. Tallapragada,Y. Kwon, Q. Liu, Zhan Zhang, Yihua Wu ,J. O’Connor and N. Surgi. * JHT sponsored. Project Goals and Emphasis .

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Hurricane Model Transitions to Operations at NCEP/EMC

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  1. Hurricane Model Transitions to Operations at NCEP/EMC 2009 IHC Conference, St. Petersburg, FL Robert Tuleya*, V. Tallapragada,Y. Kwon, Q. Liu, Zhan Zhang, Yihua Wu ,J. O’Connor and N. Surgi * JHT sponsored

  2. Project Goals and Emphasis Participate in the yearly operational implementation of HWRF Upgrade HWRF system Trouble shoot problems Goal: increase both track and intensity skill Continued collaboration with URI, Florida State, GFDL, and others

  3. HWRFHurricane Forecast System NHC storm message Position domain Get OBS, Model Input initial & boundary conditions Ocean Initialization Initialize wake, loop currents & eddies Wrf si(used for topographical parameters) Wrf real:replace with interpolations from native model data storm analysis and data ingest 6hr 1st guess vortex relocation 3DVAR gsi for both nests HWRF model Coupled with POM Next cycle Synoptic fields for many variables Create file for track, intensity, etc

  4. HWRF – GFDL

  5. HWRF 2008 Skill

  6. Hourly intensity Hourly model data Model atcf data Model variability may be important ?

  7. Season statistics not affected

  8. Sfc Temperatures Problems in HWRFremaining b.c. noise?? 3 2 1 4 (fixed)

  9. Fay 082018Impact of Tsfc fix: (improved track, more intense) Tsfc fix Tsfc fix Hwrf Hwrf HWRF prod HWRF prod

  10. Gustav 083100Impact of Tsfc fix: (improved track, same intensity) Tsfc fix HWRF prod Hwrf Tsfc fix HWRF prod Hwrf

  11. Other potential improvements • Surface flux formulations • Land surface modeling • Gravity wave drag • High resolution

  12. Reduced Surface Drag

  13. Noah LSM studies - Background GFDL Slab LSM 1) One level, only predicts surface temperature, wetness is fixed, no runoff Noah LSM 1) The operational LSM in NCEP's operational mesoscale forecast model (Ek et al., 2003) 2) Multiple soil layers (usually 4 layers: 0-10,10-40, 40-100 and 100-200 cm depth) with a one-layer vegetation canopy 3) Spatially varying root depth and seasonal cycle of vegetation cover 4) Frozen soil physics for cold regions, and improved soil and snowpack thermal conductivity. 5) The Noah LSM predicts soil moisture, soil temperature, land surface skin temperature, land surface evaporation and sensible heat flux, and total runoff. 6) The HWRF runoff prediction using the Noah LSM can then be used as forcing input to EMC's Streamflow Routing Scheme (Lohmann et al., 2004). Additionally, 7) The HWRF-Noah forecasts of soil moisture and runoff are good spatial indicators of soil moisture saturation (water logging) and flooding.

  14. HWRF Predicted Tracksof Katrina Other sfc & bl physics Obs With/withoutNOAH LSM

  15. 12 Hour Accum. Rainfall (mm) OBS NAM HWRF 48h 48h 48h 72h 72h 72h Observed rainfall is the rain gauge measurement Observed rainfall spreads in larger area than NAM and HWRF rainfall did

  16. Forecasted Stream Flow (m3 s-1)

  17. Influence of orography on the atmosphere Create obstacles and additional turbulence Gravity wave drag Change the large scale flows Generation of vertically propagating gravity waves Change the track of hurricanes

  18. Motivations • Track forecast skills of HWRF on Eastern Pacific storms are not as good as those on Atlantic storms • Diagnotics of HWRF indicates the anomalous flows developed over Mexican Plateau seems to cause the less skillful track forecast of HWRF • Proper GWD representation might improve the track forecast of HWRF • GWD improved NAM Results NEXT PAGE

  19. No GWD GWD ~ 50nm improvement at t=120hr

  20. High Resolution HWRF Experiment • Resolution - Control: 0.18, 0.06 (~27km, ~9km) - High Res: 0.09, 0.03 • Domain - Control: 216x432, 60x100 - High Res: 432x862, 118x198 • Time Step - Control: 54, 18 (sec) - High Res: 27, 9 (sec) • Ocean Coupling - Coupled with HYCOM (resolution remains the same) - Coupling time: every 9 minutes • Case Study - Hurricane RITA, starting from 2005092012

  21. 9 km 4.5 km More banding

  22. 4.5km (HRES) HWRF somewhat more accurate

  23. HWRF Accomplishments • HWRF severely test in the active Atlantic Season. HWRF ran in a robust, timely fashion . HWRF competitive with best operational guidance. • HWRF installed GWD and fixed sfc temperature issues • HWRF working on LSM, sfc parameterizations, and higher resolution. HWRF Plans • Upgrade physics, initialization and test ensembles • More extensive & quantitative diagnostics • Implement new ocean & wave model

  24. The NMM-WRF Modeling Systemhttp://www.dtcenter.org/wrf-nmm/users/ • Regional-Scale, Moving Nest, Atmospheric Modeling System. • Non-Hydrostatic system of equations formulated on a rotated latitude-longitude, Arakawa E-grid and a vertical, pressure hybrid (sigma_p-P) coordinate. • Advanced HWRF,3D Variational analysis that includes vortex reallocation and adjustment to actual storm intensity. • Uses SAS convection scheme, GFS/GFDL surface, boundary layer physics, GFDL/GFS radiation and Ferrier Microphysical Scheme. • Ocean coupled modeling system (POM GFDL).

  25. Technical Details of Operational HWRF POM Coupled System run by NCEP Central Operations

  26. Sporadic SLP noise • Sea level pressure diagnostic • Model or post processing ?? • Traced to grid movement Noise

  27. Eliminate SLP Noise • Modify topographic smoothing zone • Adjust mass fields • No more Noise !

  28. Background (2) The GFDL Slab LSM is the default in HWRF: The initial soil moisture remains fixed in time during the HWRF forecast. Moreover, the initial conditions of soil moisture in the Slab LSM are a fixed field that never change throughout the year and thus are unable to capture antecedent soil moisture conditions. The Slab LSM does not predict the runoff response to HWRF precipitation forecasts, thus cannot predict streamflow from HWRF forecasts. LGM

  29. Why do we need GWD parameterization? NWP models use grid-averaged (smoothed) terrain data Coarse resolution models ( > 4km) cannot resolve the GWD caused by subgrid scale topography

  30. HWRF Track Skill • Competitive with other guidance • Better than GFDL & NGAPS • GFS & UKMET quite good • Few long lasting storms in 2007 • EPAC HWRF not as good HWRF

  31. HWRF Intensity Skill • Competitive with other guidance • Some improvement over GFDL at early times • Not a good year for dynamic models after accounting for landfall • EPAC intensity degraded-no ocean coupling HWRF

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