# Presentation: 359815

## Thirty Years of Operational Ocean Wave Forecasting at Fleet Numerical Meteorology and Oceanography Center 

- Paul Wittmann and Mike Clancy
- Fleet Numerical Meteorology and Oceanography CenterMonterey, CA  93943

**Notes:**
The FNWC Singular Wave model only computer sig wave ht. and only one wave component which is propagated and decayed. Even though it used simple empirical growth and dissipation curves, it yielded operationally useful results.  (Hurbert, W.E, 1964)

The Med SOWM was the first operation spectral wave model to be run operationally. Developed though a cooperative effort between FNWC and NYU.  Used combined Miles/Phillips growth mechanisms.  Used 15 freq. bands and 12 directional bands.  Forced by the NH PE Marine winds. (Pierson, W.J., Cardone, V.J., Lazanoff, S., Stevenson, N.M.)

The NH SOWM had the same physics and spectral resolution as the Med SOWM. The propagation in
Both models used the icosherdral grid, where the grid lines are great circles routes. (Cardone, V.J., Lazanoff, S., Stevenson, N.M)

GSOWM, same physics as SOWM, different propagation scheme (regular lat/lon grid) increased directional
Resolution( 15 deg).  Forced by NOGAPS (GSCLI) Coincided with Cyber 205 (Clancy, R.M., Kaitala, J.E., Zambresky, L.F)   

Med WAM replaces Med SOWM, 1st generation replaces by 3rd generation, new physics, NORAPS forcing, runs on a .25x.25 lat/lon grid. ( WAMDI Group, Hasselmann, K. et al.) We are waiting for Cray Y-MP 16 to implement WAM globally.

Global WAM 1994, and regional nested WAM’s forced by NORAPS/COAMPS with the acquisition of the Crays.

WW3 global and regional models (Tolman, H.) coincides with the acquisition of the SGI Origin 2K. New physics, improved propagation scheme, MPI.  Start support of DIOPS nearshore and surf models. 

The evolution of wave models is dependent on the evolution of the NWP models, for example GSOWM was
Made possible by NOGAPS, and the evolution of computer hardware. Often we were waiting for bigger machines to
Run global implementations and high res models.

## Singular Wave Model

- Developed by W.E. Hubert and B.R. Mendenhall.
- Used empirical growth curves to compute significant wave height and average wave periods from winds.
- Used simple time decay of swell to simulate wave dissipation.
- Used ray tracing techniques to propagate a single swell component along great circle paths.
- Became operational at Fleet Numerical for the Northern Hemisphere in 1964.

## The Spectral Ocean Wave Model (SOWM)

- Developed by W.J. Pierson, T. Inoue, V.J. Cardone.
- Implemented  at Fleet Numerical by S.M. Lazanoff and N.M. Stevenson.
- Used a spectral resolution of 15 frequency and 12 directional bin.
- Used a combined and modified Phillips/Miles wave growth mechanism for wave growth.
- Included wave dissipation due to opposing winds.

## SOWM (Continued)

- Wave propagation was accomplished using a “jump” technique, where the wave energy is propagated to the surrounding grid points after sufficient time has passed.
- The Mediterranean SOWM became operational at Fleet Numerical in 1973.
- The Northern Hemisphere SOWM became operational at Fleet Numerical in 1975.

## Slide 5

**Notes:**
Example of NH SOWM. Large storm 61ft waves in the Gulf of Alaska.

##  Global Spectral Ocean Wave Model (GSOWM)

- GSOWM built upon the success of the first-generation SOWM models.
- Contained essentially the same growth and dissipation formulations as SOWM.
- Increased the directional resolution to 24 bins (15 degrees).
- Used a new wave propagation method that ran on a spherical 2.5o x 2.5o global grid, forced by NOGAPS.
- GSOWM became operational at Fleet Numerical in 1984.

## Slide 7

**Notes:**
Example of GSOWM for the North Altlantic

## Third Generation Wave Model (WAM)

- Developed by the WAM Development and Implementation  Group, an international an international group led by Klaus Hasselmann.
- Included explicit parameterization of non-linear wave interactions.
- Used Snyder wind growth formulation (later changed to Janssen growth term).
- Used wave dissipation developed by Hasselmann and Komen.

## WAM (Continued)

- Initially implemented in 1990 for the Mediterranean basin on a 0.25o x 0.25o grid, forced by NORAPS.
- Implemented globally in 1994 on a 1o x 1o grid, forced by NOGAPS.
- Many high resolution nested regional areas were added and driven by mesoscale NWP models (NORAPS and later COAMPS).

## Slide 10

**Notes:**
Example of MedWAM.

## Third-Generation Wave Model (WAM)

**Notes:**
Three mission areas for NAVMETOCCOM..

Additional Talking Points

## Wave Heights Predicted byCOAMPS/WAM During Hurricane Floyd

- Wave Heights Predicted byCOAMPS/WAM During Hurricane Floyd

**Notes:**
Three mission areas for NAVMETOCCOM..

Additional Talking Points

## WaveWatch III

- Third-generation wave model similar to WAM, developed by Hendrik Tolman of NCEP.
- Uses Tolman/Chalikov wave growth equations.
- Improved third-order accurate wave propagation scheme.
- Uses the Message Passing Interface (MPI) routines to achieve efficient operation on distributed memory computer architectures.
- Implemented at Fleet Numerical in partnership with NCEP.

## WaveWatch III (Continued)

- Became operational at Fleet Numerical for global and nested regional application, fully replacing WAM, in 2001.
- Initial global implementation in 2001 on a 1o x 1o  grid; upgraded to a 0.5o x 0.5o global grid in the fall of 2002 to coincide with a comparable upgrade in NOGAPS resolution.
- Regional implementations forced by COAMPS for each COAMPS region.

## Slide 15

**Notes:**
Example of global WW3

## Slide 16

**Notes:**
Global WW3 vs. altimeter measurement for Oct 2003. Tau=0

## Published Validation Studies of Wave Models at Fleet Numerical

-     **Model     RMSE      Date       Measurement   Reference**
**    ****-----     ----      ----       -----------   ---------**
**    ****SOWM      1.92      Jan 1985       Buoys   Clancy et al. 1986**
**    ****GSOWM     1.36      Jan 1985       Buoys   Clancy et al. 1986**
**    ****GSOWM     0.94      Mar 1992       Buoys   Wittmann et al. 1994**
**    ****WAM       0.74      Mar 1992       Buoys   Wittmann et al. 1994**
**    ****WAM       0.65      Jan/Feb 2000   Buoys   Wittmann, 2002**
**    ****WW3       0.67      Jan/Feb 2000   Buoys   Wittmann, 2002**
**    ****WAM       0.63      Jan/Feb 2000   ERS-2   Wittmann, 2002**
**    ****WW3       0.58      Jan/Feb 2000   ERS-2   Wittmann, 2002**

## Quick Overview of Wave Model Historyat Fleet Numerical

- Singular Wave Model  1964 -1974
- Mediterranean SOWM   1972 -1990
- Northern Hemisphere SOWM   1974 - 1984
- Global SOWM  1984 - 1994
- Mediterranean WAM  1990 - 2001
- Global WAM  1994 -2001
- Nested Regional WAMs   1994 - 2001
- Global and Regional Wavewatch III   2001- present

**Notes:**
The FNWC Singular Wave model only computer sig wave ht. and only one wave component which is propagated and decayed. Even though it used simple empirical growth and dissipation curves, it yielded operationally useful results.  (Hurbert, W.E, 1964)

The Med SOWM was the first operation spectral wave model to be run operationally. Developed though a cooperative effort between FNWC and NYU.  Used combined Miles/Phillips growth mechanisms.  Used 15 freq. bands and 12 directional bands.  Forced by the NH PE Marine winds. (Pierson, W.J., Cardone, V.J., Lazanoff, S., Stevenson, N.M.)

The NH SOWM had the same physics and spectral resolution as the Med SOWM. The propagation in
Both models used the icosherdral grid, where the grid lines are great circles routes. (Cardone, V.J., Lazanoff, S., Stevenson, N.M)

GSOWM, same physics as SOWM, different propagation scheme (regular lat/lon grid) increased directional
Resolution( 15 deg).  Forced by NOGAPS (GSCLI) Coincided with Cyber 205 (Clancy, R.M., Kaitala, J.E., Zambresky, L.F)   

Med WAM replaces Med SOWM, 1st generation replaces by 3rd generation, new physics, NORAPS forcing, runs on a .25x.25 lat/lon grid. ( WAMDI Group, Hasselmann, K. et al.) We are waiting for Cray Y-MP 16 to implement WAM globally.

Global WAM 1994, and regional nested WAM’s forced by NORAPS/COAMPS with the acquisition of the Crays.

WW3 global and regional models (Tolman, H.) coincides with the acquisition of the SGI Origin 2K. New physics, improved propagation scheme, MPI.  Start support of DIOPS nearshore and surf models. 

The evolution of wave models is dependent on the evolution of the NWP models, for example GSOWM was
Made possible by NOGAPS, and the evolution of computer hardware. Often we were waiting for bigger machines to
Run global implementations and high res models.

## Summary and Outlook

- Fleet Numerical has pioneered operational wave forecasting for over 30 years.
- The combined effect of improvements in ocean wave model and NWP models has improved forecast error significantly.
- Fleet Numerical will continue to partner with NCEP to achieve ongoing upgrades to WaveWatch III
- In addition to the traditional support provided for hazard avoidance, optimum track ship routing, and surf forecasting, Fleet Numerical wave models will play a new and important role supporting the Sea Basing component of the Navy’s Sea Power 21 doctrine.

- This presentation is dedicated to the late Willard J. Pierson, whose groundbreaking development of spectral ocean wave models laid the foundation for practical ocean wave predictions and operational ocean wave models.