Project Description
The aim of the JOULE project JOU2-CT93-0390, WERATLAS, is the
assessment of the wave energy resource available along the European
coasts. To avoid the strong spatial variability associated to coastal
topography and geometry, the information which is to be provided as a
PC Atlas will cover offshore deep water conditions. Coastal conditions
at a site of interest could be estimated from the WERATLAS data using
a suitable coastal wave model.

Ideally, long term statistics should be based on measured
data. Two type of measurements are presently available:

1) long time series at fixed positions, mostly obtained with buoys,

2) extensive measurements in space, but desultory in time, obtained with
satellite altimeters. While their overall amount is rapidly growing with time,
those are still far from the quantity and spatial coverage required for a
generalised statistics.

The alternative source is the output of sophisticated wave models, that
provide a detailed description of the wave conditions over the whole basin of
interest. The limit to the accuracy of their results is mostly determined by
the accuracy of the input wind. While the present meteorological models are
capable of remarkable accuracy in the description of the surface wind fields,
particularly in the open oceans, their quality deteriorates when we move back
in time - key are 1987 and 1991, when, following the evolution of computer
power, substantial model improvements took place.

The two main European sources of information about wind and waves are the
European Centre for Medium-Range Weather Forecast (ECMWF, Reading, UK) and
the UK Meteorological products from the two centres revealed that ECMWF data
was the more accurate data set. We have therefore based our analysis on this
source.

ECMWF runs daily two wave models, one globally and one for the
Mediterranean Sea, since July 1992. To extend the analysis period, the wave
model (the third generation WAM model) was run for the Atlantic ocean since
1987 using the locally archived wind fields. This has not been possible for the
Mediterranean Sea, because of the low quality of the wind fields in this area
before the latest improvement.

The wave model data are being validated, and possibly calibrated, using
available buoy and satellite data. Note that the calibration is possible only
under certain conditions (spatial uniformity being the stringent one) and after
a careful screening of the data with respect to the height, period and
direction.

Where the wave model results are less reliable, we use only the
available measured data. This is the case for the Norwegian Sea (near the
northern limit of the model) and the North Sea (due to the coarse resolution
used in the Atlantic wave model).

We summarise below the main characteristics and the locations of the
available data.

ATLANTIC OCEAN
1. Wave modelling
grid resolution 3 deg x 3 deg
period: 1987-1995
information: Hs, TTheta, TP, Theta

2. Measurement
Buoys
Norwegian Sea (data provided by OCEANOR)
Moere
Haltenbanken
Traenabanken
Vesteraalbanken
Nordkappbanken
Utsira
Tromsoflaket
North Sea (data provided by RIKZ, Netherlands)
AUK
K13

North Atlantic (for verification/calibration)
West Shetland (UK)
South Uist (UK)
Figueira da Foz (PT)


Extensive satellite altimeter data (Geosat, ERS-1 and Topex-Poseidon).


MEDITERRANEAN SEA
1. Wave modelling
grid resolution 3 deg x 3 deg
period: 1992-1995
information: Hs, TTheta, TP, Theta

2. Measurement
Buoys

Of the several available stations, depending on their
location and extension in time, we have used

Alghero (Italy)
Palma (Spain)
Satellite data have been used in the eastern Mediterranean Sea.