© KNMI 2004

The Wave Modelling (WAM) Group

A historical perspective

Gerbrand Komen

BMRC, 6 december 2004

Klaus Hasselmann

Overview

1. Pre WAM

2. The WAM model and the Wave Modelling Group

(~1980 – 1994)

3. Post WAM

Pre - WAM

1. Pierson: wave spectrum

2. Gelci: dynamic equation

3. Hasselmann et al (JONSWAP): observations

4. Models, SWAMP

Giuseppe Santomaso

1907 - 1990

Pre - WAM

1. Pierson: wave spectrum

2. Gelci: dynamic equation

3. Hasselmann et al (JONSWAP): observations

4. Models, SWAMP

F = F (k, x, t )

cg = cg ( k )

Pre - WAM

1. Pierson: wave spectrum

2. Gelci: dynamic equation

3. Hasselmann et al (JONSWAP): observations

4. Models, SWAMP

scaling

Pre - WAM

1. Pierson: wave spectrum

2. Gelci: dynamic equation

3. Hasselmann et al (JONSWAP): observations

4. Models, SWAMP

Early models

GONO, HYPA, UKMO, . . .

For wind sea: use observed growth curves

to determine wave height from wind speed and

estimated wave age

Reconstruct spectral shape from scaling laws

Add swell

Validate

Intercompare -> SWAMP

The WAM model

The emergence of a 3rd generation models

1. The problem: Snl

2. Susanne Hasselmann Miami 1981, Exact NL

3. Hamburg 1983 , study the actual balance

omega = omega ( k ) = sqrt ( g k )

N ~ F

Webb, Matsuda, Hasselmann and Hasselmann . .

The emergence of a 3rd generation

models

1. The problem: Snl

2. Susanne Hasselmann Miami 1981, Exact NL

3. Hamburg 1983, study the actual balance

4. Sendai, 1984

The WAM group

1. Hamburg 1984

2. WAM = Wave Modelling group

- model implementation: global/regional

- growth curve reanalysis

- directional effects

- data assimilation of satellite observations

3. Funding: EU, ECMWF, SCOR

WAM

1. Source terms

- wind input, Charnock parameter

- nonlinear transfer

- dissipation/whitecapping

- shallow water effects

- current refraction, sea ice

2. Validation

3. Operational implementation

WAM

Outreach

Annual meetings (1984 - 1994)

Course on Ocean Waves and Tides (ICTP, 1988)

Dynamics and Modelling of Ocean Waves (1994)

Venice, 1985

KNMI, 1994

Post WAM

1. WISE (Leo Holthuijsen, Luigi Cavaleri)

2. Freak waves (Peter Janssen)

3. Probability Forecast ECMWF (Jean Bidlot et al)

4. BMRC (Diana Greenslade)

5. Decadal variability in global extreme statistics

(Sofia Caires, Andreas Sterl, Gerbrand Komen)

Post WAM

1. Probability Forecast ECMWF

2. BMRC (Diana Greenslade, Ian Young)

3. Decadal variability in global extreme statistics

Spatial scale of background errors in the model SWH (Diana Greenslade,BMRC)

Post WAM

1. Probability Forecast ECMWF

2. BMRC

3. Decadal variability in global extreme statistics

Summary

It was successful

It was fun:

- nice to work with all these people

- nice to understand ocean waves