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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2009 IHC Conference, St. Petersburg, FL
V. Tallapragada,Y. Kwon, Q. Liu, Zhan Zhang,
Yihua Wu ,J. O’Connor and N. Surgi
* JHT sponsored
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
HWRFHurricane Forecast System
NHC storm message
Get OBS, Model Input
initial & boundary conditions
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
3DVAR gsi for both nests
Coupled with POM
Synoptic fields for many variables
Create file for track, intensity, etc
Hourly model data
Model atcf data
Model variability may be important ?
GFDL Slab LSM
1) One level, only predicts surface temperature, wetness is fixed, no runoff
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.
HWRF Predicted Tracksof Katrina
Other sfc & bl physics
Observed rainfall is the rain gauge measurement
Observed rainfall spreads in larger area than NAM and HWRF rainfall did
Create obstacles and additional turbulence
Gravity wave drag
Change the large scale flows
Generation of vertically propagating gravity waves
Change the track of hurricanes
Results NEXT PAGE
~ 50nm improvement at t=120hr
- Control: 0.18, 0.06 (~27km, ~9km)
- High Res: 0.09, 0.03
- Control: 216x432, 60x100
- High Res: 432x862, 118x198
- Control: 54, 18 (sec)
- High Res: 27, 9 (sec)
- Coupled with HYCOM (resolution remains the same)
- Coupling time: every 9 minutes
- Hurricane RITA, starting from 2005092012
4.5km (HRES) HWRF somewhat more accurate
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.
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