99 
Figure 3. Grey scale images of anomaly heights in the north 
east Pacific constructed from the data shown in 
Figure 2 and from 25 other tracks, for the cycles 1 
(top, mean date, 16 Nov 1986), 4 (centre, 23 Jan 
1987) and 7 (bottom, 26 Feb 1987). 
Figure 4. Grey scale images of anomaly heights in the Gulf 
of Alaska, constructed from the data shown in 
Figure 2 for cycle 13 (top, mean date, 8 June 
1987), 15 (centre, 12 July 1987) and 17 (bottom, 
15 August 1987).