1096 
behind the storm front, and the other two foci about 
200 miles behind the front. These discrepancies must 
be expected, since waves generated at the front itself 
could not gather sufficient energy to be perceptible at 
the wave station; furthermore, the distance between 
the point of wave origin and the storm front must be 
larger for the farthest disturbance, which is almost 3000 
miles from Pendeen. 
18 12 
20 MARCH W hone 
MARINE METEOROLOGY 
Iceland, Pendeen came under the influence of the fetch 
in the cold sector, which remained at about the same 
distance from Pendeen. In the meantime the fetch in 
the warm sector of the second storm moved slowly east- 
ward, and on 18 February this and the fetch remaining 
from the first storm appeared as a single generation 
area. By 19 February the first storm had undergone 
complete frontolysis. The only remaining fetch was that 
06 06 12 18 
12 | 
12 MARCH [ 13. MARCH 
STORM. PATH ACROSS THE ATLANTIG 
/ Pe Piel | | (ape i 
2 
a 77/7 
£0 
lds 
WY, 
ZY 
a 
° 
o 
o 
g 
8 
DISTANCE FROM PENDEEN 
IN NAUTICAL MILES 
YY; 
_ 
— 
VY, 
Lip 
—Z 
aoeeess 
{y) 
& 
SECONDS 
a 7 
— Yj 
Doe 
RECORDED WAVE PERIODS 
AT PENDEEN 
14 MARCH 
16 20 12 
So 
ae 
15 MARCH 
— 
WAVE PERIOD IN SEGONDS 
16 MARCH 
08 12 
Fie. 12—Comparison of storm path with period band. The shaded band in the upper part shows the movement of the 
storm system toward the wave station. The forward and rear edges of the storm were determined by 6-hourly weather maps, 
of which every fourth map is shown in Figs. 6-9. The computed storm positions (foci) are marked A, B, 
F. The limits of 
the period band in the lower part were determined from the wave spectrograms shown in Fig. 5. (From Munk [9].) 
Figure 13 illustrates the application of the method to 
a more complex meteorological situation. Two storm 
systems which existed simultaneously could be identified 
and traced separately. On 15 February 1945 the de- 
velopment of a cyclone started off the east coast of the 
United States. On 17 February the center of the cyclone 
had reached mid-Atlantic, and an unusually well-de- 
fined 1000-mile fetch in the warm sector was pointing 
directly toward the wave station. At the same time a 
new low-pressure area had just moved off the east coast 
of the United States and formed a second fetch imme- 
diately north of Bermuda (Fig. 13, upper right). As 
the first storm stagnated and veered northward toward 
in the cold sector of the second storm, which was moy- 
ing northward toward Iceland. 
The spectrograms shown in Fig. 13 are more compli- 
cated than those in the preceding examples, and the 
interpretation is much more difficult. The first three 
foci fall in the first storm as it moved across the At- 
lantic. Foci D to H are associated with wave trains that 
were formed as the first storm veered northward and 
its fetch was joined with the fetch of the second storm. 
Only by that time had the main-period band moved 
sufficiently into the lower periods to permit identifica- 
tion of a wave train, F’, from the distant second storm. 
Foci J to N originated from the joint fetch existing from 
; 
