Advanced Hurricane Prediction

1. Advanced Hurricane Prediction A plan for research and development Naomi Surgi February, 2005

2. Requirements Process Societal Impacts: • More people living along coastal areas – takes longer to evacuate • Evacuations are costly: ~$1M per mile of coastline evacuated • Evacuation numbers depend on hurricane size and intensity • More hurricane related fatalities now due to inland flooding

3. Stakeholder Requirements • Improved track forecast skill – where and when? • Extend track forecasts out to 5 days • Improved hurricane intensity forecasts • intensity at landfall – how strong? • onset of gale force winds at coastline (structure) – how big & when? • Skillful heavy rainfall forecasts out to 3 days in advance

4. Operational TC Forecast Issues: • Continued advancement of TC track forecasts • Improved TC intensity prediction (genesis and rapid intensification) • Improved prediction of TC surface wind distribution (structure) • Improved rainfall forecasts • TC waves, storm surge

5. TPC Atlantic 72-hr Track Forecast Errors With the exception of “erratically” moving storms, while hurricane track prediction has shown remarkable progress, skill in predicting intensity/ structure changes is still poor. It is expected that high resolution, advanced NWP modeling systems may continue to improve track as well as intensity, structure predictions. Hurricane WRF is the next step towards this goal.

7. Lowest track errors on record for GFS, GFDL models and TPC!

8. How NOAA Improved Track Forecasts Three components of modeling system: • HIGH QUALITY OBSERVATIONS(large scale environment surrounding hurricane, e.g. satellite, aircraft) • MADE BETTER USE OF OBSERVATIONS IN HURRICANE MODELS (advances in data assimilation) • IMPROVED HURRICANE MODELS(improved numerical techniques and representation of physical processes)

9. Advanced Data Platforms for Hurricanes • Environment: (Winds, Moisture, Temperature) – to define steering currents • Satellite: Advanced Satellite Instruments • (AMSU, GOES, NPOESS etc.) • In-situ: Aircraft (dropsondes)

10. NCEP Global Forecast System 6 hr Forecast and WV Imagery

11. Jung and Zapotocny JCSDA Funded by NPOESS IPO Satellite data ~ 10-15% impact

12. Synoptic Surveillance Pattern

13. Impact Of Dropsondes On NCEP Global Model Track Forecasts Note: Improved skill at all forecast times in 2002 and 2003

14. Intensity Guidance Most skill

15. Charley deepened From 964 mb to 941 mb in 4 h 35 min near landfall – NIGHTMARE!

16. Science Issues to address Intensity/Structure • ENVIRONMENTAL FORCING • “good vs. bad” trough interactions • SST changes (including ocean subsurface) • CONVECTIVE SCALE PROCESSES • total rainfall – organization of convection, eyewall vs. Stratiform • MICROPHYSICS– LIQUID VS. ICE • INNER CORE REGION • scale interaction – feedback between vortex dynamics, convective physics and environment • triggering and adjustment processes – eyewall replacement cycles, eyewall mixing

17. Science Issues – con’t • AIR SEA INTERACTION: OCEANIC/ATMOSPHERE BOUNDARY LAYER) • Air sea fluxes under disturbed conditions (sea spray) • Turbulence and subgrid scale mixing • Coupled atm/ocean model; coupled wind-wave model • UPPER OCEAN PROCESSES • SST changes – depth of warm layer (accounts for turbulent mixing, horizontal advection) e.g. Gulf Stream and loop currents, warm core eddies, cold wakes • LAND SURFACE PROCESSES • PBL fluxes – storm structure -- coupling to hydrologicprocesses

18. To advance TRACK forecasts AND improve INTENSITY, STRUCTURE and RAIN Forecasts: • Need high quality hurricane core* and environmental observations • Need advanced data assimilation techniques for environment and hurricane core • Need advanced modeling system • Need a “disciplined” approach for transition from research to operations, e.g. JHT, JCSDA * critical observations for intensity/structure and rain problem

19. Advanced Observation Platforms for Hurricanes • Environment (Winds, Moisture, Temp.) • In-situ: G-IV, UAV’s, Driftsondes • Satellite: ADVANCED MICROWAVE INSTRUMENTS • Hurricane Core (Winds from 12 km to surface) • G-IV, WP-3D airborne Doppler radars • 88-D Level II data • UpperOcean (SST’s, wave height, mixed layer info) • AXBTs, Altimeter, ARGOS, Current Meter, Buoys

20. Required Data Assimilation Development • Advanced Data Assimilation Techniques • Environmental flow – in progress (some success) • Hurricane Interior - substantial R&D necessary* • Ocean data assimilation – new effort (GODAS) • * EMC is developing scale-dependent covariances

21. Hurricane WRF (HWRF) Prediction System • Community based next generation hurricane prediction system • Will replace the GFDL in 2007 • Coupled air-sea-land prediction system • Advanced data assimilation for hurricane vortex • Advanced physics for high resolution • Land surface coupled to hydrology/inundation • Nested wave prediction • Coupling to dynamic storm surge (in planning)

22. TRANSITIONING TO HURRICANE WRF 020304 05 06 07 Mesoscale Data Assimilation for Hurricane Core GFDL frozen HWRF T&E Continue upgrades GFDL Begin Physics Upgrades HWRF Operational Transition to HWRF MM5 HWRF T&E Preliminary Test HWRF physics HWRF Begin R&D

23. Pre-Implementation Strategy for HWRF • INCREASE RESOLUTION • UPGRADE GFDL PHYSICS WITH GFS PHYSICS • IMPLEMENT MICROPHYSICS, SFC. PHYSICS • PUT PHYSICS IN WRF FRAMEWORK • MIGRATE ALL PHYSICS TO NMM, e.g. HWRF • CARRY OUT TEST & EVALUATION ON UPGRADED GFDL SYSTEM (GFDL FROZEN ’05-06) • PERFORM EXTENSIVE COMPARISONS BETWEEN GFDL AND HWRF FOR MULTIPLE SEASONS AND STORMS

24. DEVELOPMENT OF THE HWRF SYSTEM • Movable, nested grid (configuration, domain) • Advancement of physics (wheel of pain) • Initialization (development of DA for hurricane vortex) (LONG TERM EFFORT) • Coupling to HYCOM • Coupling to WAVEWATCH III (+ multi-scale model) • Coupling to LSM • Development/Upgrade of hurricane verification system (PPT, STRUCTURE) • Coupling to storm surge-wave coupled model (planning stage) • HWRF ensembles

25. “THE PHYSICS WHEEL OF PAIN” Compliments of Dr. Jaiyu Zhou (NOAA/OST) Direct Physical Interaction of Clouds • - Hydrometeor type (phase) • - Cloud optical properties • - Cloud overlap (merging Cu, grid-scale cloudiness) • - Cloud fractions • - Precipitation • - Sfc energy fluxes • 4. - Convection, PBL evolution, precipitation Radiation Cu Scheme Sfc & PBL Grid Scale Microphysics

26. Hurricane-Wave-Ocean-Surge-Inundation Coupled Models NCEP Atmosphere and Ocean NOS land and coastal waters HWRF NOAH LSM runoff High resolution Coastal, Bay & Estuarine hydrodynamic model surge inundation fluxes Atmosphere/oceanic Boundary Layer radiative fluxes other fluxes winds air temp. elevations currents 3D salinities temperatures SST currents HYCOM 3D ocean circulation model wave spectra WAVEWATCH III Spectral wave model wave fluxes

27. HYCOM Expt – Hurricane Isabel • MODEL: • HYCOM Mercator North Atlantic 1/12 degrees (∆x ≈ 7 km). • 26 vertical coordinates. • Vertical viscosity and mixing: GISS. • FORCING: 6-h NCEP (GFS analysis). • INITIAL CONDITIONS: from near-real time North Atlantic system (NRL & RSMAS) (O.M. Smedstad). • PERIOD: Sept. 3-30, 2003

28. SSH and cross section positioning ∆H~30 cm

29. Temperature cross sections for Sept 11, 15-21, 30

30. GFDL Coupled Model

31. C-BLAST BUOYS DURING FRANCES

32. Hurricane Frances – impact of coupling Blue- GFDL operational coupled model Red- GFDL uncoupled model

33. The Future Deep ocean model resolution dictated by GFS model Higher coastal model resolution dictated by model economy Highest model resolution in areas of special interest Hurricane nests moving with storm(s) like GFDL and HWRF

34. Technology Infusion Joint Hurricane Testbed Mission Statement: The mission of the JHT is to transfer more rapidly and smoothly new technology, research results, observational and model advances into improved tropical cyclone analyses and prediction at operational hurricane forecast centers.