# Presentation: 041576

- Stephen J. Lord
- and  the HWRF Team

- NCEP/Environmental Modeling Center

**WHERE  AMERICA’S  CLIMATE  AND  WEATHER  SERVICES  BEGIN**

- Advanced Hurricane Modeling
- at EMC:   The HWRF

**Notes:**
Some of the season highlights include
 12 tropical storms of which 8 became hurricanes
 5 major hurricanes, all Category 4...an all-time record
 5 year total of 41 hurricanes...an all-time record
 3 hurricanes (Bret, Floyd, Irene) and 2 tropical storms (Dennis and Harvey) made landfall in the mainland U.S.

## HWRF TEAM

**Naomi S., Qingfu L., Vijay T., **
**Young K., Bob T.,  Zhan Z. and Janna O’C, H.-S. Kim **
**Also, thanks to Isaac G., J.-W. Bao, **
**And HYCOM team at MMAB/EMC**

## Overview

**HWRF ’08 implementation**
**Current Operational HWRF configuration**
**2008 HWRF end-of-the-season performance**
**T&E for 2009 HWRF upgrades**
**The Advanced HWRF **

##  HWRF ’08 implementation

**HWRF Analysis Changes:**
**Improved initialization of weak storms**
**Dynamical Balance: surface pressure adjustment based on gradient wind stream function (more accurate)**
**Changes to POM initialization:**
**Feature based assimilation of mesoscale oceanic features**
**Assimilate more than one warm core rings as well as cold core rings**
**Rings can be assimilated close to the loop current**
**HWRF Physics changes / Bug fixes:**
**Initialize TKE to zero (HWRF does not use TKE based PBL)**
**Adjustment of temperature and pressure fields after nest motion to remove noise at the lateral boundary of nest domain**
**HWRF Script Changes:**
**Improved functionality of all HWRF scripts**
**HWRF scripts for EMC parallels are consistent with operational configuration**
**Test results follow**

## H041: Operational HWRF implemented FY 2008

**H041: Operational HWRF implemented FY 2008**

**Reduced intensity forecast errors**
**(mostly due to reduced negative bias)**

**2007 HWRF**

**2008 HWRF**

**Intensity Error**
**[Dennis, Katrina, Rita, Wilma, Dennis] **
**2007 HWRF vs 2008 HWRF & GFDL**

## Slide 6

## H041: Operational HWRF implemented FY 2008

**Improved Track **
**Forecast Errors**

**H041: Operational HWRF implemented FY 2008**

**2007 HWRF**

**Atlantic Track Error **
**[Dennis, Katrina, Rita, Wilma, Dean]**
**2007 HWRF vs 2008 HWRF**

## 2008 HURRICANE SEASON REVIEW 

**ATLANTIC**

## 2008 HWRF

**HWRF track forecast errors are comparable to those from GFDL for the Atlantic**
**[Multi-model ensemble**
**Approach]**

**2008 HWRF**

**2008 GFDL**

**Atlantic Track Error**
**2008 HWRF**** & ****2008 GFDL**

## Atlantic Track Error

**HWRF track forecast errors are comparable to those from ****GFDL**** and ****GFS**** for the Atlantic (MME)**

**Atlantic Track Error**
**2008 HWRF**** & ****2008 GFDL ****&**** ****GFS**

## Atlantic Intensity Error

**HWRF Performed better than GFDL (about 1-2 kts) up to 84-hr forecast, some degradation (about 2 kts) at 96- and 120-hr forecasts.**

**Atlantic Intensity Error**
**2008 ****HWRF**** & ****GFDL**

## BERTHA (02L)

**BERTHA (02L)**

**GFDL**

**HWRF**

## HWRF taking Fay to Gulf 

**HWRF taking Fay to Gulf **

## HWRF

**HWRF**

**GFDL**

**Gustav (07L)**

**HWRF tracks are more**
**consistent (less forecast**
**to forecast variation)**

## HWRF

**HWRF**

**GFDL**

**Ike (09L)**

**Ike**
**One of the difficult**
**2008 storms for HWRF**

## Ike – northward turn into Fl during early stages of forecast Sept. 05, 00Z

**Ike – northward turn into Fl during early stages of forecast Sept. 05, 00Z**

**24 hrs later....**
**Sept. 06, 00Z**

## 48 hrs later.... Sep. 10 00Z

**48 hrs later.... Sep. 10 00Z**

**48 hrs later.... Sep. 08 00Z**

## 2008 HURRICANE SEASON 

**EASTERN PACIFIC**

## EPAC Track Error

**EPAC Track Error**
**2008 HWRF**** & ****2008 GFDL ****&**** ****GFS**

**HWRF, GFS still have some problems in the Eastern Pacific track forecasts**

## EPAC Intensity Error

**Positive intensity bias in the early stages of HWRF forecasts (possibly due to lack of ocean feedback?)**

**EPAC Intensity Error**
**2008 HWRF**** & ****2008 GFDL**

## 2009 HWRF IMPLEMENTATION

**Refine Hurricane Initialization (Q. Liu)**
**Gravity Wave Drag Parameterization (Kwon)**
**Sea Spray Parameterization (Fairall, Bao)**
**Bug Fix for Cooler Land Surface Temperatures in the inner domain (Tuleya, Zhang)**
**HWRF-HYCOM Coupled System will run in parallel to the operational HWRF-POM System (H-S Kim, MMAB)**
**Testing: Tallapragada, O’Connor, et al.**

## 2009 HWRF Testing Protocol

**Test 2008 HWRF with GSI upgrades - ****DONE**
**Test each upgrade candidate on relevant cases for 2008 ops GFS- ****DONE**
**Test each upgrade candidate with GSI upgrades – ****IN PROGRESS**
**Combine candidates into single experimental system for final testing, including**
**GSI upgrade**
**Any GFS changes**
**IN PROGRESS**

## QL08: New HWRF Initialization

**QL08: New HWRF Initialization**
**Early results indicate improved track and intensity forecasts for Hurricane Dean**

## ~ 50nm improvement at t=120hr

**No GWD**

**GWD**

**~ 50nm improvement at t=120hr**

## Negligible impact on Atlantic Hurricanes (neutral) for strong benchmark cases

**No GWD**

**GWD**

**Negligible impact on Atlantic Hurricanes (neutral) for strong benchmark cases**
**(testing in progress for weaker storms)**

**H41A: Bench Mark 2008 HWRF; H044: w/Gravity Wave Drag. Dennis/Katrina/Rita/Wilma (2005) and Dean 2007**

## Sea Spray: Negligible impact on Atlantic Hurricane track forecasts (slight degradation at 120 hrs)

**Sea Spray**

**No Sea Spray**

**Sea Spray: Negligible impact on Atlantic Hurricane track forecasts (slight degradation at 120 hrs)**

## Sea Spray

**Sea Spray**

**No Sea Spray**

**Sea Spray: Increased intensity errors due to increased positive  intensity bias**

## Cold Land Surface Temperatures in HWRF moving grid

**Cold Land Surface Temperatures in HWRF moving grid**

**Cooler (by about 6-10 deg) land surface temperatures due to irregular computation of radiation in the inner domain (due to nest motion)**

**Problem solved by calling radiation for the nest at regular intervals**

**Radiation consistent with parent domain (54 min.)**

**Radiation called at nest motion threshold interval (9 min)**

## HWRF-HYCOM Experiments

**Configuration of HWRF-HYCOM coupled system is complete. **
**HYCOM better represents the Ocean physics than POM.  However, there is a cold bias in SST, possible due to heat budget and wind stress**
**Preliminary results show weaker storms in the Atlantic.**
**Work in progress.  **
**Improved version of HWRF-HYCOM slated to go in parallel FY 2009.**

## Hurricane Forecast Improvement Project (HFIP)

**Accelerate skill of numerical guidance and associated products**
**Intensity**
**Track**
**Major foci**
**Ensemble systems**
**Data assimilation**
**Impact of high resolution**
**Physics improvements**
**Established Teams**
**	****	****Regional data assimilation**
**	****	****Ensemble-based guidance**
**	****	****Global and regional models and physics**
**	****	****Ocean model and coupling**
**	****	****Diagnostics**
**	****	****Product generation**

## Hurricane Diagnostics

- Ongoing and continuous efforts to develop a system for comprehensive model diagnostics for hurricane forecasts
- Primary tasks include:
- Evaluation of initial storm structure (analyzed),
- Vortex evolution in the forecasts,
- Representation of large-scale flow in HWRF and GFDL compared to the GFS
- Impact of boundary conditions, domain configurations
- Impact of physics, ocean feedback, horizontal and vertical resolution
- Evaluation of derived diagnostic products including energy, angular momentum and PV budgets
- Collaborative effort with Mark DeMaria

**HPLOT capabilities**
**  ****Model side-by-side **
**    ****comparison**
**  ****Standard diagnostics**
**  ****vert. shear**
**  ****x-sections, etc.**
**  ****Based on generic software**

## NOAA’s Aircraft in Hurricanes

**Working on flight strategies for GIV and P-3’s**
**Working to obtain resources for flight hrs/add’l crews**
**Operational requirement for core data at 0Z, 12Z to  initialize HWRF core circulation  (06,18Z ?)**
**Operational requirement for AXBT’s **
**Two mission profiles:     Environment ****& CORE**
**Observations:                  GPS, ****Radar, AXBT’s**** **
**New operational status of P-3’s **

##    Atm/ocean boundary layer, enthalpy fluxes       

**    ****09                  10**                **11                 12                     13**

**Doppler Radial velocities  Reflectivity  **

**Mesoscale Data Assimilation for Hurricane Core**

**  **

** **

**  **

**          ****Advancing the  HURRICANE WRF System**

**Atm. Model  physics and resolution upgrades (continuous) **

**   ****Atm/ocean boundary layer, enthalpy fluxes       **
**                            ****Microphysics, radiation  **

**        ****Incr. Res:  4-6km/100L?    **

** **

**                                                ****Land surface Coupling**** **
**Waves****:  multi-grid/surf-zone physics**
**Ocean:****  4km.    - continuous upgrades in  Ocean Data Assimilation **

- .

**HWRF Ensembles**

**Experimental advanced assimilation techniques**
**	****	****EnsDA****	****        4D-var     ****	****     Hybrid**

## THANKS

**Questions? **

## Additional Slides

- ATLANTIC HURRICANE TRACKS

## HWRF SYSTEM 

**High resolution **
**Coastal, Bay & **
**Estuarine **
**hydrodynamic model**

**Atmosphere/oceanic Boundary Layer**

**HYCOM**
**3D ocean circulation**
**model**

**WAVEWATCH III**
**Spectral wave model**

**NOAH LSM**

**NOS**
**land and coastal waters**

**NCEP/****Environmental Modeling Center**
**Atmosphere- Ocean-Wave-Land**

**runoff**

**fluxes**

- wave fluxes

-                    wave
-                  spectra

- winds
- air temp.

- SST
- currents

- elevations
-        currents
- 3D   salinities
-         temperatures

- other fluxes

**surge**
**inundation**

- radiative
- fluxes

**HWRF SYSTEM **

**NMM hurricane atmosphere**

## 2009-2012 HURRICANE UPGRADE PLAN

**  ****Data assimilation:****  **
**Advanced initialization for hurricane core -  assimilate airborne doppler radar obs (new radar on GIV, P-3’s)  to define storm strength and storm structure in HWRF analyses.  (will run in parallel in ’07)**
**Continuous upgrades to HWRF  hurricane core initialization through advanced 4-D data assimilation  for winds and reflectivity (requires nearly continuous obs for hurricane structure from storm top to surface beginning in depression stages through evolution of storm lifecycle).  Augment doppler data with GPS sondes.  Also, explore use of satellite microwave data. **
**  ****Model resolution upgrades:  **
**Increase in resolution:  Horizontal 3-6km. /Vertical resolution ~100levels (dependent on results of current studies).   **
**Hurricane Ensembles:  Hi-res hurricane model ensembles, e.g. 4km?  Multi model ensembles? (e.g.  GFDL, GFDN, HWRF)  Work on development of HWRF ensembles in progress.  **

##   Model Physics:  Continuous upgrades to atm/ocean boundary layer (fluxes), microphysics, deep convection (cloud resolving scales?), radiation  

** ****Coupling to land surface model w/ adv. Sfc. Physics for improved rainfall forecasts at landfall.   Important input to hydrology and streamflow  models to address inland flooding.   **
** ****Advance Wave Model (WAVEWATCH III) to forecast waves up to the beach, ie:  improve non-linear interactions, surf zone shallow water physics, wave interactions with currents **
** ****ALL hurricane model  physics upgrades dependent on allowable resolution, e.g. affordable complexity of microphysics, sea spray, explicit representation of all clouds.     **

## ARTHUR (01L)

**ARTHUR (01L)**

**GFDL**

**HWRF**

## GFDL

**GFDL**

**HWRF**

**Cristobal 03L**

## Dolly (04L)

**Dolly (04L)**

**GFDL**

**HWRF**

## Edouard (05L)

**Edouard (05L)**

**GFDL**

**HWRF**

## HWRF

**HWRF**

**GFDL**

**Josephine (10L)**

## HWRF

**HWRF**

**GFDL**

**Kyle (11L)**

## HWRF

**HWRF**

**GFDL**

**Laura (12L)**

## HWRF

**HWRF**

**GFDL**

**Marco (13L)**

## HWRF

**HWRF**

**GFDL**

**Nana (14L)**

## HWRF

**HWRF**

**GFDL**

**Omar (15L)**

## HWRF

**HWRF**

**GFDL**

**Paloma (17L)**

## Additional Slides

- Eastern Pacific HURRICANE TRACKS

## HWRF

**HWRF**

**GFDL**

**Alma (01E)**

## HWRF

**HWRF**

**GFDL**

**Douglas (04E)**

## HWRF

**HWRF**

**GFDL**

**Elida (06E)**

## HWRF

**HWRF**

**GFDL**

**Fausto (07E)**

## HWRF

**HWRF**

**GFDL**

**Genevieve (08E)**

## HWRF

**HWRF**

**GFDL**

**Hernan (09E)**

## HWRF

**HWRF**

**GFDL**

**Iselle (10E)**

## HWRF

**HWRF**

**GFDL**

**Julio (11E)**

## HWRF

**HWRF**

**GFDL**

**Karina (12E)**

## HWRF

**HWRF**

**GFDL**

**Norbert (15E)**

## HWRF

**HWRF**

**GFDL**

**Odille (16E)**

## HWRF

**HWRF**

**GFDL**

**Polo (18E)**

## Additional Slides

- Details of Upgrades to Initialization

## 2009 Upgrades - HWRF Initialization

***Change in the minimum surface pressure specification*****; make the surface pressure-wind relationship more consistent with the model instead of the observation**
***Redefine the filter domain size based on observation*****.**
**Filter domain is defined too large in some cases, particularly near frontzone or waves.**
**Define filter domain in GFS analysis data as 1.1 times the radius of outmost isobar.**
***Set the limit for small size storm***
**HWRF has problems to forecast intensity for small size storms, we set**
**Radius of maximum wind       19 km**
**Radius of the outmost isobar      334 km**
***Search maximum wind position at 10m height instead of the first level height***
**Convert the model level 1 wind to 10m, then search the position of the maximum wind**
***Increase the search area for the maximum wind in high latitude storms***
**set the maximum search radius as 4.5 degrees for storms stronger than 30m/s and in north of 30****0****N.**

**Notes:**
The slope is replaced with the observed P-W slope (coefficient should be different for modeled P-W) which is smaller than that in the current HWRF model. So pressure is reduced or increased less for the same wind increment. We also limit the maximum difference between the observed MSLP (pobs) and the new MSLP (pnew) as 20mb.

## Additional Slides

- Details of GWD Parameterization

## Mountain blocking

**Mountain blocking**

**Gravity wave vertical propagating and breaking**

## Influence of orography on the atmosphere

**Create obstacles and additional turbulence**

**Generation of vertically propagating gravity waves**

**Gravity wave drag**

**Change the large scale flows**

**Change the track of hurricanes**

## Why do we need GWD parameterization?

**NWP models use grid-averaged (smoothed) terrain data **

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

## X

**X**

**Z**

**∆****X=33km**

**∆****X=3.3km**

**∆****X=10km**

**Simulation results of various resolutions show that a coarse model does not produce enough gravity wave drag caused by terrain**

## Motivations

**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 **

_**Motivations**_

**Results    NEXT PAGE **

## Additional Slides

- Details of Sea Spray Parameterization in HWRF

## The ESRL Sea-Spray Scheme

_**The ESRL Sea-Spray Scheme**_
**Wind-dependent source parameterization**
**Thermal feedback –  warm-up of surface layer at high winds**
**Momentum feedback – surface drag reduction**
***Purpose:  To take into account sea-spray effects on the surface ******	******     momentum and heat fluxes ***

_**Implementation in the HWRF model**_
- The ESRL sea-spray scheme is called by (and appended to the end of)  the subroutine **module_bl_gfs.F**.
- A function routine (function qsat_spray) is added to the function subroutine **module_gfs_funcphys.F**.
- Evalution runs have been conducted at EMC for Katrina (2005), Rita (2005), Dennis (2005) , Wilma (2005) and Dean (2007).

## Results of Evaluation Testing

**For strong storms (such as Katrina and Rita), the scheme tends to produce a greater positive bias of intensity during the first 48-72 hours than the control runs, while the impact on track is negligible.**
**For weak storms (such as Dennis), the scheme tends to produce an intensity bias that varies around that of the control runs, while the impact on track is slightly degraded after 72 hours.**
**The storm structure is affected by the sea-spray mediated momentum and heat fluxes, suggesting a strong connection between the surface fluxes and the vortex dynamics through the convection in the eyewall.**
**The performance of the scheme can be improved by tuning the source function and the degree of feedback effects.**

##  HWRF ’08 implementation

**HWRF Analysis Changes:**
_**Weak storm treatment:**_**  The weak storm is a weighted blend of the guess and the composite storm. Weights are based on the observed storm intensity and the vertical structure of the guess storm**.
_**Storm Balance:**_**  Instead of assuming gradient wind balance, surface pressure is treated as a function of non-linear gradient wind stream function.  Once surface pressure is adjusted, vertical temperature fields are adjusted based on hydrostatic balance.**
**Changes to POM initialization:**
**Feature based assimilation of mesoscale oceanic features**
**Assimilate more than one warm core rings as well as cold core rings**
**Rings can be assimilated close to the loop current**
**HWRF Physics changes / Bug fixes:**
**Initialize TKE to zero (HWRF does not use TKE based PBL)**
**Adjustment of temperature and pressure fields after nest motion to remove noise at the lateral boundary of nest domain**
**HWRF Script Changes:**
**Improved functionality of all HWRF scripts**
**HWRF scripts for EMC parallels are consistent with operational configuration.**

## Intensity Forecast Skill Comparison: NAOMIex: HWRF-HYCOM Coupled System

## Sea Spray Parameterization in HWRF

- Collaborative Effort with C. W. Fairall and J.-W. Bao of NOAA ESRL
- Experiments for Benchmark Cases conducted on Vapor by Bao at ESRL
- Preliminary results indicated increased positive bias in the HWRF intensity forecasts (and thus increased errors)
- Further tuning should be possible to reduced the bias and increase the forecast skill.
- So far negligible impact on track forecasts.

## Parameterization of Orographic Gravity Wave Drag (GWD)

**Diagnostics of HWRF forecasts for the Eastern Pacific Hurricanes indicates that 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**
**Probable candidate for 2009 implementation**

## 2009 Upgrades - HWRF Initialization

***Change the minimum surface pressure specification based on observations***
***Redefine the filter domain size based on observations***
***Set the limit for small size storm***
***Search maximum wind position at 10m height instead of the model first level***
***Increase the search area for the maximum wind in high latitude storms***

**Notes:**
The slope is replaced with the observed P-W slope (coefficient should be different for modeled P-W) which is smaller than that in the current HWRF model. So pressure is reduced or increased less for the same wind increment. We also limit the maximum difference between the observed MSLP (pobs) and the new MSLP (pnew) as 20mb.

## HWRF

**HWRF**

**GFDL**

**Marie (14E)**

**Another difficult storm**

## HWRF

**HWRF**

**GFDL**

**Cristina (03E)**

**More Consistent**

**Increased Spread**

## HWRF

**HWRF**

**GFDL**

**Lowell (13E)**

**Difficult storm for HWRF **

## HWRF

**HWRF**

**GFDL**

**Boris (02E)**

## 48 hrs later.... Sep. 12 00Z

**48 hrs later.... Sep. 12 00Z**

**Landfall .... Sep. 13 06Z**

## HWRF

**HWRF**

**Ike Forecast starting at 2008090906**

**6 hours later – all others follow suite**

## HWRF

**HWRF**

**GFDL**

**Hanna (08L)**

## Fay (06L)

**Fay (06L)**

**GFDL**

**HWRF**

**Tracks stayed south of the gulf coast**

## HWRF vs. GFDL

**HWRF**** ****vs.**** ****GFDL**

**HWRF still has some problems in the Eastern Pacific track forecasts.**

## Done

**Done**

**Add’l**
**Tuning**

**Done**

**Done**

**2009**
**Para**

## Hurricane Diagnostics and Plotting Tool: HPLOT

**Enhanced capabilities to view model output from two different models for a side-by-side comparison.  **
**Ability to plot the differences between two model forecasts interpolated to a common resolution**
**Plotting tracks and intensities on any displayed graphics**
** **
**Computation of some standard hurricane-related diagnostics including zonal and meridional components of vertical shear, arbitrary and single point cross sections, mean flow between different vertical layers and plotting skew-T plots.  **
**HPLOT is continuously being upgraded to add further capabilities of statistical evaluation of model forecasts (RMS errors, bias, anomaly correlations etc.)**
**This is a GUI based software with easy to navigate menus and features.**

## HPLOT Visualization Software

**Comparison of HWRF/GFDL forecasts for 850-200 hPa mean wind. Anomalous blocking pattern along the west coast in HWRF.**

**HPLOT Visualization Software**

## HWRF Pre-implementation T&E FY2008

**Upgrades to HWRF were tested for a selected set of Atlantic Hurricanes (Benchmark)**
**DENNIS, KATRINA, RITA, WILMA (2005) and DEAN (2007)**
**Results showed significant improvements to track and intensity forecasts**
**Major improvements in reducing the negative bias of HWRF intensity forecasts**