Altimeter wind and wave data and Ocean Wave Forecasting
Peter Janssen(1) , Saleh Abdalla(1) , and Jean Bidlot(1)
Shinfield Park ,
Reading RG2 9AX,
Over the past fifteen years there has been a continuous interplay between
ocean wave forecasting and altimeter wind and wave observations. First,
the prospect of the availability of global observations of wind and waves
from the ERS-1/2 satellites provided a significant stimulus to the
development of modern, third-generation wave prediction systems. And
vice versa, the development of the altimeter wind and wave product was
stimulated by the need to have reliable wave predictions.
Furthermore, wind and wave model products have been vital in the
monitoring of the quality of the altimeter
products, in particular in the first stages of the commisioning phase,
while, on the other hand, the comparison between
altimeter and wave model results has given clear guidelines for
improvement of wave prediction systems. In 1993 the
quality of the altimeter wave product was regarded so high that centres
such as the Met Office and ECMWF decided to assimilate these data into
the wave forecasting system, giving high quality analysed wave height
fields. Although during the past 13 years we have seen considerable
improvements in wind and wave modelling, it will be shown
that the assimilation of altimeter wave height data is still of vital
importance for the quality of the analysed wave height field.
Presently, the quality of the atmospheric and wave model analysis is so
high that satellite retrieval algorithms have been developped on the
basis of atmospheric analysis and forecast products. Examples are the
scatterometer algorithms CMOD4 and CMOD5, the altimeter wind speed
algorithms for Jason and ENVISAT and the total column water vapour
algorithm for the MWR instrument on ENVISAT.
During the presentation, an overview of the above mentioned
developments will be given, while we also discuss the accuracy of the
altimeter and model wave height.