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Ann. Geophys., 25, 581-595, 2007
www.ann-geophys.net/25/581/2007/
© European Geosciences Union 2007
Assimilation of radar altimeter data in numerical wave models: an impact study in two different wave climate regions
G. Emmanouil1, G. Galanis1,2, G. Kallos1, L. A. Breivik3, H. Heiberg3, and M. Reistad4
1University of Athens, School of Physics, Division of Applied Physics, Atmospheric Modeling and Weather Forecasting Group, University Campus, Bldg. PHYS-V, 15784 Athens, Greece
2Naval Academy of Greece, Section of Mathematics, Xatzikyriakion, 185 39, Piraeus, Greece
3Norwegian Meteorological Institute, Research and Development Department, Section of Remote Sensing, POB 43 Blindern, 0313 Oslo, Norway
4Norwegian Meteorological Institute, Forecasting Division of Western Norway, Allégaten 70, 5007 Bergen, 0313 Oslo, Norway
Abstract. An operational assimilation system incorporating significant wave height
observations in high resolution numerical wave models is studied and
evaluated. In particular, altimeter satellite data provided by the European
Space Agency (ESA-ENVISAT) are assimilated in the wave model WAM which
operates in two different wave climate areas: the Mediterranean Sea and the
Indian Ocean. The first is a wind-sea dominated area while in the second,
swell is the principal part of the sea state, a fact that seriously affects
the performance of the assimilation scheme. A detailed study of the
different impact is presented and the resulting forecasts are evaluated
against available buoy and satellite observations. The corresponding results
show a considerable improvement in wave forecasting for the Indian Ocean
while in the Mediterranean Sea the assimilation impact is restricted to
isolated areas.
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