256 
PACIFIC SCIENCE, Vol. XVII, July 1963 
to identify the trains of smaller waves or waves 
of similar azimuths. This time requirement and 
the different optimum directions of viewing 
reduces the value of interpretation from photo- 
graphs alone; in addition, photographs them- 
selves must be interpreted later — a more diffi- 
cult process than direct visual interpretation of 
the wave azimuths. Direct visual observation 
also permitted the determination of the direc- 
tion of wave progress, relative to the positions 
of foam patches. Timing the interval between 
the appearance of a foam patch at the crests of 
successive waves provided an estimate of wave 
periods. 
In addition to wave data, observations on 
wind direction and speed at the water surface 
were obtained. The wind direction was taken 
as the azimuth of the long narrow parallel wind 
slicks which appeared where wind speed ex- 
ceeded Beaufort 3. Wind speed was estimated 
according to the Beaufort scale of water surface 
characteristics (Bowditch, 1943:52), as shown 
below. 
BEAUFORT 
NUMBER 
DESCRIPTION 
OF SEA 
SPEED 
(km/hr) 
0 
mirrorlike 
0-2 
1 
wavelets 
2-6 
2 
short waves 
6-12 
3 
scattered whitecaps 
12-19 
4 
many whitecaps 
19-30 
5 
foam streaks 
30-40 
The author does not apologize for not using 
a more modern and sophisticated technique 
involving elaborate camera arrangements or 
electronic scanning devices, because direct ob- 
servation is simpler and sufficient for the prob- 
lem. 
WINDS 
Weather maps for the period, based upon 
ship and shore stations as well as upon TIROS 
photographs, are illustrated by Figure 1. The 
two high pressure areas north and northeast of 
Hawaii are characteristic of the season. A low 
pressure area about 800 km southeast of Hawaii 
discovered by TIROS satellite was mild and its 
effect was not detected during the flights. The 
isobars show that the wind in the vicinity of 
the Hawaiian Islands should have been from 
about 070° (east-northeast); this is typical of 
the trade-wind period of the year. 
A far more detailed picture of the wind pat- 
tern was provided by aerial observation (Fig. 
2). On the windward side of the islands the 
wind speed was Beaufort 4 except adjacent to 
the island of Hawaii, whose blocking effect re- 
duced the wind to below Beaufort 2. On the 
immediate leeward side of the islands the wind 
was reduced to Beaufort 1 by shielding effects. 
Between the islands the wind was sped by fun- 
nelling, so that a speed of Beaufort 5 occurred 
between Hawaii and Maui. A tongue of Beau- 
fort 4+ extended from between Oahu and Mo- 
lokai to a position off the south coast of Oahu. 
Verification of its presence was obtained by 
anemometer readings aboard R/V "Argo” of 
Scripps Institution of Oceanography, which 
worked in that area during 2 September. These 
tongues of high wind speed expanded and joined 
laterally well to the lee of Maui. However, still 
farther to the southwest is an area of winds less 
than Beaufort 3 having an unknown extent. 
Possibly this area is the result of the combined 
lees of all the islands; if so, it would be of in- 
terest to learn how much farther southwestward 
the area extends. 
Wind direction was estimated from slicks 
which were long (to 500 m), narrow (a few 
meters), and occurred in parallel series (5-50 
m apart ) parallel to the wind. These wind slicks 
are zones of convergence between cells of surface 
water caused to rotate around horizontal axes by 
the wind (Woodcock, 1944). Oil (perhaps from 
phytoplankton) collects in the convergences and 
changes the light reflectivity and wave pattern, 
as observed by Dietz LaFond (1950). Other 
debris, including sugar mill wastes, were locally 
present in some slicks. The wind slicks were re- 
stricted to areas having wind speeds of Beaufort 
3 or more, and are one of many phenomena 
which are dependent upon this critical wind 
speed (Munk, 1947). As shown by Figure 2 the 
windflow lines, deduced from the wind slicks, 
spread apart to pass around the islands, particu- 
larly around large and high Hawaii. Their con- 
centration in the straits causes the high wind 
speeds there. 
In areas having wind of less than Beaufort 3, 
wind slicks were usually absent. In the lee of 
Hawaii and Maui their place was taken by slicks 
