Naomi Surgi

1
Advanced Hurricane Modeling at EMC The HWRF

Naomi Surgi
Hurricane Program Leader
NCEP/Environmental Modeling Center
WHERE AMERICAS CLIMATE AND WEATHER SERVICES
BEGIN
2
Overview

• HWRF implementation strategy
• HWRF development
• Results HWRF vs. GFDL
• HWRF for the future

3
TRANSITIONING TO HURRICANE WRF
02-03 03-04 05
06 07
Mesoscale Data Assimilation for Hurricane
Core
GFDL
Final GFDL upgrades
Continue upgrades
Begin Physics upgrades

HWRF
Prelim. Testing grid, hurricane physics
IOC
Begin RD
TE
4

• Pre-Implementation Strategy for HWRF
• FOR THE HWRF OPERATIONAL IMPLEMENTATION
• HWRF MUST PERFORM AT LEAST AS WELL AS THE GFDL
  MODEL
• UPGRADE GFDL SYSTEM / Establish GFDL as
  benchmark
• - UPGRADE GFDL PHYSICS WITH GFS PHYSICS (04)
  
• (GFS SAS and PBL schemes)
• - INCREASE RESOLUTION (05)
• (inner nest from 18 to 9km.)
• - IMPLEMENT EMC Ferrier MICROPHYSICS to GFDL
• - Upgrade AIR-SEA PHYSICS (reduced drag)
  06
• - IMPROVE OCEAN INITIALIZATION
• TRANSITION GFDL UPGRADES TO HWRF

5
HWRF Development

• CONDUCTED 25 EXPERIMENTS, e.g. 25 versions of
  the HWRF
• Tested each upgrade (numerics, physics, coupling)
  for clean comparisons - comprehensive testing
  gt200 cases
• Next 2-3 weeks FINALIZE HWRF (ocean coupling
  for hi-res nest, vortex initialization, cumulus
  momentum mixing)
• PERFORM EXTENSIVE COMPARISONS BETWEEN GFDL AND
  HWRF FOR MULTIPLE SEASONS AND STORMS
• (04, 05, 06)

6
Other upgrades for 07 GFDL TE already underway
for new global system GFS (Hybrid) 382/64L
SIGMA/P (in trop) New Data Assimilation System,
e.g. GRID POINT STATISTICAL INTERPOLATION (GSI)
7

• THE HURRICANE WRF (HWRF)
• PREDICTION SYSTEM
• HWRF began development 2002
• Operational this season GFDL will run in
  parallel
• Non-hydrostatic hurricane model movable, inner
  nest
• Coupled air-sea-land prediction system
• Advanced data assimilation for hurricane core
  (make use of airborne doppler radar obs and land
  based radar)

8

• HWRF continued..
• Assimilation of ocean observations
• Advanced physics for high resolution and
  air-sea
• Coupling with wave model
• Land surface coupled to hydrology/inundation
• Coupling with dynamic storm surge

9
Hurricane-Wave-Ocean-Surge-Inundation Coupled
Models
NOS land and coastal waters
NCEP/Environmental Modeling Center Atmosphere-
Ocean-Wave-Land
HWRF SYSTEM

NMM hurricane atmosphere
NOAH LSM
runoff
High resolution Coastal, Bay Estuarine
hydrodynamic model
surge inundation
fluxes
Atmosphere/oceanic Boundary Layer
radiative fluxes
winds air temp.
other fluxes
elevations currents 3D salinities
temperatures
SST currents
HYCOM 3D ocean circulation model
wave spectra
WAVEWATCH III Spectral wave model
wave fluxes
10

• THE Coupled HWRF SYSTEM
• 2007 Initial Operating Capability
• Movable, 2- way nested grid (9km 27km/42L
  75X75)
• Advanced Physics (atmosphere-waves-ocean)
• Coupled to Ocean (POM)
• Advanced vortex initialization (3-D var)
  parallel run w/radar data
• Multi-grid wave model - (static multi-grids,
  some shallow water physics)

11
Wave model development

• 07 - operational implementation of multi-grid
  wave model with static grids and initial
  surf-zone physics.
• 08 - development of re-locatable grids.
• 08 - incorporation in HWRF with relocatable
  grids, advanced stress computation and expanded
  shallow water physics.

12
The multi-grid wave model
Deep ocean model resolution dictated by GFS model
This is the 2003 vision In 2007 areas will mimic
areas of NWS forecast responsibility
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
13
Wave model resolution in minutes for operational
implementation in FY2007-Q4, mirroring WFO NDFD
responsibilities.
14
HWRF Results 4X daily throughout 04, 05, 06
hurricane season for all storms system very
stable and reliable Over two hundred cases with
prelimary HWRF system Results from a subset of
these
15
HWRF (coupled- parent domain)
TRACK
16
Intensity
17
HWRF DENNIS
18
HURRICANE EMILY
19
HWRF Hurricane Katrina
20
HWRF Hurricane Wilma
21
Forecast Spread Katrina 2005
GFDL
HWRF
22
Forecast Spread Wilma 2005
HWRF
GFDL
23
Forecast Spread Ernesto 2006
GFDL
HWRF
24
WHATs NEXT ????
25

• THE Coupled HWRF SYSTEM
• Couple to HYCOM, WAVEWATCH III (08)
• Improve data assimilation of airborne and land
  based radars for hurricane core initialization
  (continuing)
• Advance Physics sea spray (08-09)
  (collaboration with ESRL, URI) , improved stress,
  cloud/radiation
• Waves up to the coastline (Non-linear
  interactions, surf- zone shallow-water physics)
  (collaboration w/USA, HRD)
• Land surface coupling to streamflow and
  inundation
• (collaboration w/USA, HRD)
• Development of HWRF ensembles
• Coupling to dynamic storm surge model (w/NOS)

26
Advancing HURRICANE System
08 09 10
11 12
Mesoscale Data Assimilation for Hurricane Core
Radial vel./ reflectivity Adv. DA
SDBE

Atm. Model physics and resolution upgrades
(continuous)
Atm/ocean boundary layer wave drag,
enthalpy fluxes (sea spray)
Microphysics, Radiation
ENSEMBLES???


Incr. resolution (6km/gt64L)
Prototype Ens w/Navy

Land coupling
Implement

Waves surf-zone physics implement
Ocean 4km. - continuous upgrades in
RTOFS

Storm surge???
27

• Development of Advanced Probabilistic Guidance
  for Intensity/structure (in progress)
•  HWRF Ensembles
• Configuration
• initial conditions, resolution,
  members???
• OR
•   Use of multi model ensembles (MME)
• (Explore shared MME w/Navy - Demo 07,
  08)
• (Value of very hi-resolution deterministic
  forecasts vs. ensembles?) (LES studies in
  progress - PSU)

28
Aircraft in Hurricanes
Need to develop flight strategies for GIV and
P-3s for core missions Two mission profiles
Environment Core Observations
GPS, Radar, AXBTs Large increase in request
for flight hours for core missions HWRF
requirement 4X/day for assimilation problem
Working on operational requirement for AXBTs

29
THANK YOU FOR YOUR ATTENTION
Many thanks Gopal S, Qingfu, Bob T, Bill O,
Vijay T, Young-Kwon, Isaac G., Morris B Scott
Carter for
30
Extra slides
31
(No Transcript)
32
(No Transcript)
33
(No Transcript)
34
HWRF DENNIS
35
HYCOM TE - Dennis
36
HURRICANE EMILY
37
HWRF Hurricane Katrina
38
HYCOM TE Katrina
39
(No Transcript)
40
(No Transcript)
41
Wavewatch model at Landfall
Driven by GFS winds
Driven by GFDL/GFS winds
The eye positions are nearly identical, but the
difference in spatial scales has a huge impact on
the coastal wind fields.
42

• Two Weather Research and Forecasting (WRF) Model
  dynamical cores (noted here to avoid further
  WRF confusion)
• ? NCEP Nonhydrostatic Mesoscale Model (NMM)
• Janjic, Gerrity and Nickovic, 2001,
  MWR Janjic, 2003, MAP
• Black, Tucillo, Parallelization, Optimization,
  WRF standards
• ? NCAR Explicit Mass Core (EMC or ARM)
• Klemp, Skamarock, Dudhia, 2000, Online
• Wicker and Skamarock, 2002, MWR
• Klemp, Skamarock, Fuhrer, 2003, MWR
• Michalakes, 2002  

43

• Single digit resolutions affordable for NWP
• ? Nonhydrostatic mesoscale NWP models needed.
• ? How do we build a true mesoscale NWP model?
• - Extend a cloud model to synoptic scales and
  beyond?
• - Build on NWP experience and extend NWP models
  to mesoscales?
• ? What should a successful nonhydrostatic
  mesoscale NWP model be able to do?
• - Reproduce classical nonhydrostatic solutions
  at high resolutions
• - Competitive with mature NWP models at
  transitional resolutions. 

44
Cloud models, conventional approach (Klemp and
Wilhelmson, 1978a,b, ) MM5, DWD LM,
Nonhydrostatic Eta (Gallus and Rancic, 1996, QJ)
Three Momentum Eqns
Pressure tendency Eq.
Thermodynamic Eq. sigma-z (Gal-Chen,
Somerville, MWR), z-sigma-z hybrid ( ? Often
nonconservative, higher order, discretization ? NW
P dealing with much larger range of spatial and
temporal scales ? Specific difficulties - How
to introduce diabatic forcing? - 3D divergence
typically does not sum-up to zero, mass (etc.)
conservation? - Rigid lid on top - Computational
boundary condition on top in NWP applications
45

• The NCEP NMM
• ? Instead of extending cloud models to larger
  spatial and temporal scales, NMM built on
  experiences of NWP (Janjic et al., 2001 Janjic,
  2003), i.e.,
• - Relaxing the hydrostatic approximation,
  while
• - Using modeling principles (Janjic, 1977, 1979,
  1984)
• proven in NWP and regional climate
  applications.
• Nonhydrostatic equations split into two parts
• - Hydrostatic part, except for higher order
  terms due to vertical acceleration,
• - The part that allows computation of the
  corrections in the first part,
• - Convenient for unified systems

46

• Continued..
• ? No linearizations or additional approximations
  required, fully compressible system
• ? The nonhydrostatic effects as an addon
  nonhydrostatic module
• - Easy comparison of hydrostatic and
  nonhydrostatic solutions
• - Reduced computational effort at lower
  resolutions.
• ? Pressure based vertical coordinate.
• - Exact mass (etc.) conservation,
• - Nondivergent flow on coordinate surfaces
  (often forgotten),
• - No problems with weak stability,
• - Sigma-z system problems shifted to
  stratosphere and upper troposphere.
• ? Competitive with mature hydrostatic NWP
  models

47
? Nonhydrostatic model equations for
simplicity, inviscid, adiabatic, sigma
? F, w and e not independent, watch for
overspecification!
48
This allows a transformation of the central
coordinates at the equator to a specified location

• Coordinate system
• ? Rotated lat-lon

Rotated lat
Rotated lon
? More regular grid, longer time step
49

• NCEP Nonhydrostatic Mesoscale Model (NMM)
• Janjic, Gerrity and Nickovic, 2001,
  MWR Janjic, 2003, MAP
• Non-hydrostatic dynamics
• ? NMM Computationally robust, reliable in
  operations many tests
• NWP, convective cloud runs, PBL LES, with
  resolutions from 50 km to 100 m
• ? THREE TIMES faster than most established NH
  models
• ? NMM/HWRF
• Simplified Arakawa Shubert (Pan and Wu, 1994)
• GFS PBL/Surface physics (Troen, Mahrt, 1986
  Hong and Pan, 1996)
• Radiation (Yu-Tai Hou, 2002 Mlawer (AER), 97)
• Microphysics (Ferrier et al., 2002)
• ? HWRF prototype ran during 04, 05, 06
  hurricane season

50
Science Issues

• Fundamental questions (process/sensitivity
  studies)
• Relative role of vortex vs. environment in
  influencing intensity.
• Role of ocean. Role of Oceanic heat content.
  
• Processes within atmosphere-ocean boundary layer
  on intensity/structure changes.
• Determinants of structure and relationship with
  preexisting wave disturbance. Relationship
  between structure and intensity.

51

• Role of inner core processes for
  intensification/weakening, e.g. eyewall
  replacement cycles, mixing.
• Relative role of physics, e.g. Air-sea,
  microphysics, convection etc. on intensity change
  in various environments (sheared vs. non-shear)
  

52

• Some Model Related Issues
• Data Assimilation
• Assimilation of satellite radiances
  
• Vortex Initialization
• definition of hurricane core
  circulation
• where to take obs? difficult
  for mature storms more elusive
  weaker circulations. (obs taken during RAINEX?)
  
• Physics
• role of radiation? complexity of microphysics
  and interaction of microphysics with radiation
• atmosphere/oceanic boundary layer for coupled
  air-sea-wave problem. Momentum (wave induced
  drag) and enthalpy fluxes (sea spray complexity?)

53

• Resolution -
• relative importance of horizontal vs. vertical
  resolution for modeling intensity/structure
  (important consideration for ops)
• Coupled Ocean -
• advancements to support
• initialization
• vertical mixing
• Obs to support effort data assimilation for
  improved ocean state (discussed at 2003 Air-Sea
  workshop at EMC)
• Land Surface Coupling -
• Complexity of coupling w/HWRF?
• Sensitivity of LSM for track, structure/intensity
  , rainfall?
• Future coupling with hydrology/inundation
  models.

54

• Validation/Verification/Diagnostics
• initialization
• requirement for development of verification
  techniques
• all stages of storm evolution varying
  atmos/ocean environment
• required obs to support model diagnoistics and
  verification,
• e.g IFEX effort led by HRD
• particularly deficient in ocean obs.
• temporal and spatial scales?

55

• Development of Advanced Probabilistic Guidance
  for Intensity/structure
•  HWRF Ensembles
• Configuration
• initial conditions, resolution,
  members???
• OR
•   Use of multi model ensembles (MME)
• (Share w/Navy? COAMPS, GFDL
• NCEP HWRF, NAM)
• (Value of very hi-resolution deterministic
  forecasts vs. ensembles?)

56
HWRF TEAM Gopal S. Qingfu Liu Bob T,
Veejay T. Y. Kwon (soon)
57
HWRF atmosphere-ocean coupling

• Sea surface temperature to Atmosphere from
• Regional ocean (HYCOM) dx 8-14(km)
• SST analyses (GFS) dx 30(km)
• Radiative/turbulence fluxes to Ocean from
• Atmosphere model (HWRF) dx 27(km) 9(km)
• Boundary layer model uses surface wave
  information from
• Wave model (Wavewatch 3) dx 30(km)

58
Ocean initialization and assimilation

• Initial conditions from operational Atlantic
  forecast model (RTOFS)
• Data is assimilated during the nowcast cycle of
  RTOFS
• Boundary conditions are derived from RTOFS
• Five day forecasts are sample for volume data
  twice daily and for the external velocity and
  surface elevations three hourly.
• Data Assimilation in RTOFS
• 2D/3D Var
• Data assimilated includes
• SST
• SSH
• CTD, XBT.

59
Wave model development at EMC

• WAVEWATCH III - pre-operational and operational
  at NCEP for nearly a decade (hurricane wave
  models with GFS-GFDL winds since 2001)
• Recent developments in wave modeling are largely
  driven by the hurricane (wave) forecast problem
• Coupling of wind and wave models
• New parameterizations of wind stresses over
  waves in high wind regimes.
• Development of a multi-grid wave model to mimic
  the grid layout of HWRF (use of high-res wind
  data, coupling)

60
Multi-grid wave model

• Virtually all present wave models consider
  one-way nesting only, with low resolution
  providing boundary data for high resolution
  models.
• Hurricanes require high resolution in generation
  area, but their swells are covering full basins.
  Hurricanes therefore require two-way nesting and
  relocatable nests.
• Coupling with hurricane models for the atmosphere
  benefit from identical grids.
• NCEP Build upon the present operations design
  as multiple grids in a single model.

61
Additional benefits of a multi-grid wave model

• Consolidation of global and regional models into
  a single model
• Maximum consistency between global and regional
  models
• Natural way of reducing resolution for ensembles
  by removing highest resolution coastal grids
• Additional benefits / applications for
  relocatable nests
• On demand high resolution hazard models (plane
  crashes, oil spills etc.)
• Navy On demand high resolution coupled modeling

62
The multi-grid wave model
Hurricane described with Rankin vortex with
maximum wind 45 m/s at radius of 50km. Hurricane
moves to the right at 5 m/s. Telescoping grids
with 50, 15 and 5 km resolution. Circular outline
of domains.
63
The multi-grid wave model
Individual models with different resolution give
inconsistent results. Running as a single model
gives consistent results with variable resolution.
Tolman and Alves, Ocean Modelling 2005.
64

• THE HURRICANE WRF (HWRF)
• 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
• Coupling with wave model
• Land surface coupled to hydrology/inundation
• Coupling with dynamic storm surge

65
Development of Collaborations

• HWRF WORKSHOP JUNE 2002 (EMC)
• (45 attendees estab. hurricane community)
• 1st HWRF TUTORIAL Oct. 2004 (EMC)
• (26 attendees precocious hurr. modeling
  types)
• AIR-SEA WORKSHOP MAY 2005 (EMC)
• (35 attendees introduction of ocean
  community)
• WRF/NMM Tutorial Sept 2005 (JMT/Boulder)
• the beginning of formal training

66

• Pre-Implementation Strategy for HWRF
• Upgrade GFDL as the benchmark for the HWRF
• UPGRADE GFDL PHYSICS WITH GFS PHYSICS (04)
• (GFS SAS and PBL schemes)
• INCREASE GFDL RESOLUTION (05)
• (inner nest from 18 to 9km.)
• IMPLEMENT EMC Ferrier MICROPHYSICS (in HWRF)
• UPGRADE AIR-SEA PHYSICS (reduced drag)
  06
• IMPROVE OCEAN INITIALIZATION

67
CONTINUED PRE-IMP HWRF STRATEGY

• TRANSITION GFDL UPGRADES TO HWRF
• Next 2-3 weeks
• FINALIZE HWRF (ocean coupling for hi-res nest,
  vortex initialization, cumulus momentum mixing)
• PERFORM EXTENSIVE COMPARISONS BETWEEN GFDL AND
  HWRF FOR MULTIPLE SEASONS AND STORMS 04, 05,
  06 compare to GFDL results

68
Evolution of HWRF Development

• HWRF First moving nest NMM HWRF
• GFDL Initialization 2005
  Hurricane Season Dennis
• H001 HWRF Runs with GFS Initialization 2005
  Hurricane Season Atlantic and East Pac, Near
  Real Time runs.
• H002 HWRF Runs with New GFDL Surface Physics
  Wilma, Rita and Emily
• H003 HWRF Runs with GFDL Slab Model
• H004 HWRF Runs with Two-Way Interactive Moving
  Nest (with feedbacks)
• H005/ HWRF Runs with Varying physics time steps
  (1 min. and 5 min.)
• H006

69
Evolution of HWRF Development

• H007 HWRF Runs with Varying Radiation Calls
• H008 HWRF Runs using Initialization from
  Uncoupled GFDL
• Dennis, Katrina, Rita and Wilma
• H009 HWRF Runs with Varying Physics and
  Convection time steps
• H010/11 HWRF Runs with QingFu's New
  Initialization Procedure (3DVAR) based on GFS
  analysis and GSI
• H012 HWRF Runs with New Random Number Code for
  SAS Convection
• H013 HWRF Runs with Upgraded Physics and
  Microphysics Katrina, Philippe, Rita, Wilma and
  Beryl (2006)

70
Evolution of HWRF Development

• H014 HWRF Runs with QingFu's modified
  initialization that includes a bogus vortex
  specification
• H015/016 HWRF Runs using QingFu's modified
  initialization package
• H017 HWRF Runs with New Surface Physics (Bob
  Tuleya) and inclusion of Dissipative Heating
• H018/ HWRF Runs with QingFu's modified
  initialization package (III)
• H019
• H020 HWRF Runs with Cloud Momentum Mixing
  Coefficient Introduced (kept
• at 0.5)

71
Evolution of HWRF Development

• H021 HWRF Runs with QingFu's revised 3DVAR that
  uses 10 m winds (instead of level 1 winds) for
  initialization
• H022 HWRF Runs using QingFu's modified
  initialization package (IV) that includes
  adjustment to Sea Level Pressure
• H023 First Comprehensive Testing of the
  end-to-end HWRF Modeling System. Conducted 218
  experiments that include Atlantic Hurricanes from
  2004, 2005 and 2006 seasons. Results are
  presented at
• http//www.emc.ncep.noaa.gov/gc_wmb/vxt/
• H024 HWRF Runs with new Surface Enthalpy Flux
  Coefficient
• HCBS/ HWRF Coupled Model Configuration,
  Initialization with High Resolution GFS Sigma
  Hybrid Data work in progress