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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 l.jpg
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 l.jpg
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

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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

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Hourly intensity

Hourly model data

Model atcf data

Model variability may be important ?

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Sfc Temperatures Problems in HWRFremaining b.c. noise??




4 (fixed)

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Fay 082018Impact of Tsfc fix: (improved track, more intense)

Tsfc fix

Tsfc fix



HWRF prod

HWRF prod

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Gustav 083100Impact of Tsfc fix: (improved track, same intensity)

Tsfc fix

HWRF prod


Tsfc fix

HWRF prod


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Other potential improvements

  • Surface flux formulations

  • Land surface modeling

  • Gravity wave drag

  • High resolution

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Noah LSM studies - Background


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.

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HWRF Predicted Tracksof Katrina

Other sfc & bl physics


With/withoutNOAH LSM

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12 Hour Accum. Rainfall (mm)










Observed rainfall is the rain gauge measurement

Observed rainfall spreads in larger area than NAM and HWRF rainfall did

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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

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  • 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


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~ 50nm improvement at t=120hr

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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

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9 km

4.5 km

More banding

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4.5km (HRES) HWRF somewhat more accurate

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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

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The NMM-WRF Modeling System

  • 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).

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Sporadic SLP noise run by NCEP Central Operations

  • Sea level pressure diagnostic

  • Model or post processing ??

  • Traced to grid movement


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Eliminate SLP Noise run by NCEP Central Operations

  • Modify topographic smoothing zone

  • Adjust mass fields

  • No more Noise !

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Background (2) run by NCEP Central Operations

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.


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Why do we need GWD parameterization? run by NCEP Central Operations

NWP models use grid-averaged (smoothed) terrain data

Coarse resolution models ( > 4km) cannot resolve the GWD caused by subgrid scale topography

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HWRF Track Skill run by NCEP Central Operations

  • Competitive with other guidance

  • Better than GFDL & NGAPS

  • GFS & UKMET quite good

  • Few long lasting storms in 2007

  • EPAC HWRF not as good


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HWRF Intensity Skill run by NCEP Central Operations

  • 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