104 
Figure 10. Grey scale images of average and standard deviations of the 3-day composite 
waveheight maps similar to those in Figure 9 for the north-east Pacific. Left, 
Figure 10a: average for the period November 8 1986 to December 22 1986. 
Right, Figure 10b: standard deviation, or effectively, height range for this period. 
6 CONCLUSIONS 
Geosat altimetry is providing the first convincing and 
detailed data on Rossby wave-like features. The resulting 
information on eddy formation and movement can 
considerably expand our knowledge of ocean dynamics. 
The magnitudes and distribution of the anomalies agree 
well with the available ship observations. The slopes 
measured near major height anomalies are of order 30cm 
over 100km, implying geostrophic currents of about 25cm/s. 
Such currents may play a significant role in the event of a 
major oil spill, and satellite altimetry could then be an 
important source of accurate and timely data for predicting 
oil dispersal. 
Both satellite and ship observations find that isolated eddies 
tend to be anti-cyclonic in the Gulf of Alaska. The strongest 
eddy observed off California is cyclonic with a negative 
height anomaly of 20-30cm. 
The comparison with ship data shows that eddies can be 
small enough to be undersampled with the Geosat tracks. 
The limiting sensitivity for eddy location appears to be 
about 5cm. 
The waveheight data presented also shows the limitation of 
coverage from a single satellite for operational waveheight 
mapping. However, the wave climate data available from 
Geosat should find important applications in ocean system 
design and planning and in a variety of scientific studies, 
including climate research. 
The value of a sequence of satellite data increases with the 
length of the time period covered. Geosat ceased to operate 
in mid 1989. We look forward to launch of a replacement 
system as soon as possible. 
7 ACKNOWLEDGEMENTS 
Funding from the Radar Data Development Program 
administered by the Department of Energy, Mines and 
Resources, and help with the analysis from Maria del Mar 
Martinez de Saavedra Alvarez, are gratefully acknowledged. 
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