A. The width of the upwelling zone
I n an earlier section, it was noted that the zone of biological production was probably wider than that of coastal upwelling. An attempt
is made here to make a better estimate of the width of the zone of production as a ratio of the width of the coastal upwelling.
The 13-year mean temperatures at a depth of 10 m off California
and Baja California, from 1950 to 1962, are shown in Fig. 7 (Lynn,
1967). Because of the intense sampling in the area as part of the
Calcofi programme, the distributions are well established. The physical
boundary to the coastal upwelling has been drawn by eye where the
isotherms tend to run parallel to the coast. From Baja California to
Point Conception, the boundary is about 100 km offshore, but from
Point Conception to Cape Mendocino it may be nearer 200 km. Lynn
has examined the same data in much more detail. All the temperature
130'
125'
120'
115'
I II
I
I
I
....
:
:
. . .
45. -
400 -
35' -
30' -
25'FIG. 8. Distribution of correlation coefficients of tamperaturo on date at positions off
California fitted to a harmonic regression (Lynn, 1967): the heavy broken line was
drawn by eye using the coefficient of determination.