OCEAN WAVES AS A METEOROLOGICAL TOOL 
lines of appropriate slope drawn. It is apparent from the 
figure that the foregoing interpretation of the wave ob- 
servations is consistent with the meteorological obser- 
vations. The author has found it convenient to use a 
graph [9, Fig. 5] with a special coordinate system on 
1830 GCT 
12 MAR. 1945 
60° 50° 40' 
Fie. 8—Surface weather map for 12 March 1945. 
30° 20 10° 
which periods from a single disturbance fall along a 
straight line. In this manner certain outstanding fea- 
tures on the spectrogram (such as the upper and lower 
limits) were used to determine the distance and time of 
the source region with which they are associated. 
ip. 
> 
1830 GGT 
13 MAR.1945 
t 
= 
60° © 40' 
Fic. 9.—Surface weather map for 13 March 1945. 
The information taken from the weather maps and 
the periods recorded at the wave station have been 
replotted in Fig. 12 to emphasize the similarity, with 
regard to both shape and width, between the storm 
path and the period band. The computed positions, 
designated by A, B,... F, agree fairly well with the 
information on the weather maps, especially if it is re- 
membered that these ‘‘foci’’ were obtained from theory 
without the introduction of any arbitrary constants. 
The foci A, B, and C were computed from the lower 
limit of the period band and seem to correspond to the 
1095 
forward edge of the fetch; D, H, and F were computed 
from conspicuous features near the upper limit of the 
period band and give the approximate position of the 
rear edge of the fetch. It can be seen, however, that 
focus A in the upper part of Fig. 12 is located 500 miles 
t, twat 
ty, 2 if 
Fie. 10.—Schematic presentation of propagation of wave pe- 
riods on a time-distance diagram. zx, and t, represent the po- 
sition and time of a point disturbance; x, is the position of a 
wave-recording station, showing the arrival of waves of periods 
T, and T, at times ty,1 and f»,2, respectively. 
DISTANCE FROM PENDEEN IN SEA MILES 
3000 2000 1000 (0) 
Q I! MARCH 1945 
O 12 MARCH 1945 
O 13 MARCH !945 
O 14 MARCH 1945 
CONTOURS ENCLOSE 
REGIONS WHERE THE 
ESTIMATED WIND IS 
GREATER THAN 
BEAUFORT 8,9, AND 10 
O 15 MARCH: 1945 
O 16 MARCH 1945 
Fie. 11.—Propagation diagram for 11-16 March 1945, using 
winds estimated from the pressure distribution, flowing within 
30° of a line of the recording station. (From Barber and Ursell 
(1].) 
