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

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

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

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 Operational TC Forecast Issues:

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.

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

How NOAA Improved Track Forecasts 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) Three components of modeling system:

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)

NCEP Global Forecast System 6 hr Forecast and WV Imagery

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

Synoptic Surveillance Pattern

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

Intensity Guidance Most skill

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

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 Science Issues to address Intensity/Structure

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 hydrologic processes Science Issues – con’t

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

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 Upper Ocean (SST’s, wave height, mixed layer info) AXBTs, Altimeter, ARGOS, Current Meter, Buoys

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

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)

GFDL MM Begin Physics Upgrades Mesoscale Data Assimilation for Hurricane Core Preliminary Test HWRF physics HWRF T&E HWRF HWRF Operational GFDL frozen HWRF T&E TRANSITIONING TO HURRICANE WRF Begin R&D Transition to HWRF Continue upgrades

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

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

“THE PHYSICS WHEEL OF PAIN” Radiation Cu Scheme Sfc & PBL Grid Scale Microphysics 1.- Hydrometeor type (phase) - Cloud optical properties - Cloud overlap (merging Cu, grid-scale cloudiness) - Cloud fractions 2.- Precipitation 3.- Sfc energy fluxes 4. - Convection, PBL evolution, precipitation Compliments of Dr. Jaiyu Zhou (NOAA/OST)

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

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

SSH and cross section positioning ∆H~30 cm

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

GFDL Coupled Model

C-BLAST BUOYS DURING FRANCES

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

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

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. Technology Infusion