92 
PACIFIC SCIENCE, VoL II, April, 1948 
Unfortunately, two soundings a day were not 
flown during 1946 until November. The mean 
heights for a period during the summer of 1947 
are also plotted. 
Using the average inversion heights at sched¬ 
uled radiosonde times at Honolulu, the times of 
maximum and minimum heights for the 2 days 
of special observations can be used to approxi¬ 
mate a mean diurnal curve of inversion height 
which has been drawn on Figure 4C. 
Fig. 7. Time-height section above Honolulu Air¬ 
port, June 25 to 28, 1947. 
The heights of the inversion at the weather 
ship "Bird Dog” (lat. 30°N., long. 140° W.) 
indicate a gradual slope upward to the west from 
California to Honolulu, as was noted by Von 
Ficker (1937) for the Atlantic and discussed 
by Neiburger (1945). Using the data on inver¬ 
sion height at Los Angeles collected by the Cali¬ 
fornia Stratus Investigation of 1944 (Neb 
burger, Beer, and Leopold, 1945), the mean 
slope from California to ship "Bird Dog,” a 
distance of 1,250 miles, is 1/1600. From "Bird 
Dog” to Honolulu, a distance of 1,300 miles, the 
slope is 1/3100. These slopes corroborate well 
the estimate made by Neiburger and check Von 
Ficker’s measurements over the Atlantic. 
The stratus ship just off the coast at Los 
Angeles showed the inversion base to have its 
maximum height about 0630 local standard 
time for that longitude, and minimum about 
1300. The weather ship "Bird Dog” showed a 
mean height of the inversion base higher at 
0630 than at 1830, the local times of her radio¬ 
sonde flights. Without intermediate soundings, 
it is impossible to estimate exactly when the 
maximum and minimum occur at that location. 
The hypothetical mean curve for Honolulu in¬ 
dicates that the maximum height occurs about 
1100 LST and the minimum about 2200. Since 
a radiosonde released at the Weather Bureau 
Station at the Honolulu Airport drifts west- 
southwest with the trade wind over the ocean 
during its entire flight, the sounding represents 
lee-side conditions more oceanic than insular. 
A general check on a daytime maximum inver¬ 
sion height is provided by observations of 
Powers and Wentworth (1941) on the slopes 
of Mauna Kea. From Pohakuloa, above the 
cloud deck, they noted a daytime increase in the 
height of the cloud top, which receded to lower 
levels at night. 
The diurnal variation in the height of the 
temperature inversion was attributed by Nei¬ 
burger (1944, 1945) primarily to the result of 
sea-land-breeze effects together with lesser ef¬ 
fects of advection and surface heating. He pos¬ 
tulated that the sea breeze increased the wind 
speed over the coast causing the inversion over 
the coastline to lower during the day, the air 
escaping inland through the mountain passes. 
Nighttime land-mountain breezes flowing 
toward the ocean caused the inversion gradually 
to rise during the night. This explanation fits 
less well the conditions over Honolulu than Los 
Angeles. First, the sea and land breeze does 
not appear to be stronger than on the coast of 
the continental land mass. The island is small, 
and its opposite sides lie within short horizon¬ 
tal distances. Yet there are no direct indications 
of large variations in the inversion over these 
short distances. Second, the inversion is consid¬ 
erably higher over Honolulu than over Cali¬ 
fornia, which would tend to minimize the 
diurnal height changes resulting from sea-land- 
