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Hurricane forecasts with Regional NMMB: Impact of HWRF Physics

Weiguo Wang and Vijay Tallapragada EMC/NCEP/NOAA, College Park, MD 20740

Mar. 2015

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Outline

• Importance of physics in Hurricane forecast

• HWRF physics packages into NMMB

• Hurricane simulations with regional NMMB

+ NMMB with ‘NAM physics’ vs with ‘HWRF physics’

+ NMMB with ‘HWRF phys’ vs operational HWRF

• Summary and Future work

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Introduction+ The Nonhydrostatic Multi-Scale Model on B grid (NMMB) is the second generation of nonhydrostatic models developed at NCEP. It performs well, and replaced WRF-NMM (HWRF’s dynamic core) years ago in NAM.

+ NMMB has the potential to continue to advance our hurricane forecast capability, given good parameterizations of hurricane physics.

+ Storm intensity and track are sensitive to the parameterizations of physical processes such as PBL, convection, microphysics, radiation, even land surface exchange

+ HWRF physics package has been well tested, and performed well to simulate hurricane structure in addition to intensity and track.

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HWRF physics to NMMBFollowing physics schemes used in operational HWRF have been added to NMMB:

1. GFSPBL scheme 2. GFDL surface layer plus GFDL land surface scheme3. SAS scheme 4. MESO-SAS scheme5. Add empirical z0 for hurricane to MYJ surface scheme

NMMB has “fer”, “fer_high” micophysics schemes, and “gfdl”, “rrtmg” for radiation; those are very similar to HWRF’s.

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How to use

- Options in configure files #

turbulence: gfspblhur convection: sashur sfc_layer: gfdl

land_surface: gfdlslab

- Tunable variables can be changed in configure files, default values are those currently-used in HWRF#

RUN_TC=.true. ! true='run hurricane'sas_pgcon var_ricsas_shal_pgcon coef_ric_lshallow_conv coef_ric_ssas_shalconv ALPHAsas_mass_flux SFENTHsas_mommix DISHEAT

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Operational HWRF vortexInitial conditions

GFS 0.5-degree dataBoundary Conditions

NPS

NMMBconfigure_file_d01

namelist.nps

Post/Tracker

Graphics

Can be replaced by spectral data

Will be replaced by NMMB-DA/INIT Flow chart for tests

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Configuration 01“Hwrfphys”

turbulence: gfshursfc_layer: gfdlland_surface: gfdlslabconvection: sashurmicrophysics: fershortwave: gfdllongwave: gfdl

Configuration 02“NAM-like”

turbulence: myjsfc_layer: myjland_surface: noahconvection: bmjmicrophysics: fershortwave: gfdllongwave: gfdl

NMMB Hurricane simulations27-9-3 domains, 43-level, feedback=0.5

No ocean, no DA

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ARTHUR simulated by regional NMMB with HWRF phys

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HWRF phys

NAM phys

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36 hr, near landing

10m wind

E-W cross section

NAM phys HWRF phys

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Compare NMMB using HWRF phys with Operational HWRF

NMMB (red) Intensity very close to HWRF (purple), and even better timing of max

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Another NMMB run:

turbulence: gfspblsfc_layer: myj (z0 modification)land_surface: noah

Comparison of myj/noah-LSM and GFDL/slab from NMMB runs.

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Summary • With HWRF phys package, regional NMMB can well

simulate hurricane structure, intensity and track, showing potential to further advance NCEP capability to hurricane forecast.

• Comparison with physics options in NAM shows importance of using good physics parameterizations for hurricanes.

• Future work: improve nest motion algorithm, other components (e.g., DA + init) from HWRF system, …