THE REFRACTION OF GROUPS AND OF THE WAVES WHICH THEY 
GENERATE IN SHALLOW WATER 
The paper, The Reflection of Groups and of the Waves Which They Generate 
in Shallow Water, was published in the Transactions, American Geophysical 
Union, Vol. 33, No. 4, August 1952. This work was sponsored by the Beach 
Erosion Board. An abstract of the paper follows: 
A process is described which may be of importance in beach and nearshore 
development and which may account for surging in the surf zone as well as 
other phenomena. It is shown how a group front may be refracted accord- 
ing to one law as it approaches a coast and then, after reflection, pro- 
ceed seaward under quite a different law. This permits the outgoing wave 
to move in a direction that it could not ordinarily attain, and causes 
"trapping" under many conditions. Stoneley's theory of refraction of 
energy fronts is further developed to permit quantitative investigation 
of group refraction on various types of shores. On the basis of the 
assumed hypothesis, the outgoing surf beat may be totally reflected from 
deep water, then reflected from the beach, a process which can occur re-= 
peatedly and result in newly arriving groups with varying phase relation- 
ships. Theory and techniques are developed for the investigation of the 
surf-beat path. The refraction of the reflected groups is shown to dis- 
play regions of high convergence, divergence, and reinforcement. 
NEARSHORE TEMPERATURE FLUCTUATIONS AT OCEANSIDE, CALIFORNIA 
Additional bathythermograph lowerings were made from Oceanside Pier on 
9 July, and temperature fluctuations similar to those previously reported 
were found. The installation of a thermograph at Oceanside is under con- 
sideration. The resulting temperature records would permit comparison with 
Scripps Pier records for determination of any similarities in time of occurrence 
and duration of temperature fluctuations. 
WAVE INTENSITY ALONG A REFRACTED RAY 
A return has been made to this problem in order to try out another ap- 
proximate solution for the wave intensity along a single ray. The exact 
solution for the ray equation for the case of circular contours and a linear 
variation in wave velocity has been obtained. The stepwise use of the 
solution along a general ray over complex underwater topography is being 
investigated. 
TSUNAMI RECORDER 
The tsunami recorders at La Jolla and Oceanside worked satisfactorily 
throughout the entire period. On two occasions unusual disturbances were 
noted on the recording of the microbarogram, the wind direction, and the wind 
speed. These consisted of quite regular oscillations of approximately 
7-minute period, lasting for several hours and with definite correlation 
between the three records. Inquiries reveal that no indication of these 
oscillations could be found on nearby seismographs. An attempt will be made 
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