24
GORDON A. KILEY
autumn and rapidly rose to a peak in mid-winter. This was followed
by a gradual and irregular decline, with a tendency toward a secondary
maximum in late summer, and then a rapid drop to mid-autumn.
Iselin proposed that an increase in transport would tighten and
deepen the central eddy, and Stommel’s (1948) theory of westward
intensification suggests that an acceleration of the system could move
the position of the centre closer to the Stream. A relatively small shift
in the centre could place Bermuda either in the northward drift between
the centre and the Stream or in the part of the gyre that moves toward
the southwest. Furthermore, expansion and contraction of the central
eddy could involve displacements of deep water throughout the whole
eddy system as well as in the Gulf Stream itself.
This hypothesis provides a framework that can logically contain all
of the fragmentary evidence on seasonal variations of conservative and
non-conservative properties in the Bermuda area. It also provides a
possible reason for a systematic seasonal change which involves only
a slight geographical displacement rather than a profound change in
circulation patterns. However, this is a limited view of a very complex
problem, as will be apparent to anyone who reads Iselin (1940) and
other works involving the broad implications of changes in Gulf Stream
transport. More thorough study is needed, over a broader area, and
until that is done any conclusions are speculatory.
If there is any validity in the hypothesis that has been proposed,
one would suppose that oceanic areas subject to that kind of seasonal
variation would be quite limited. Variations due to intrusions of
particular water masses are likely to be more common. I n the long
range view the Bermuda case may seem trivial, hardly warranting the
present long and diffuse discussion. However, in the present state of
our knowledge a difficult problem such as this one cannot be neglected.
Finally, it should be pointed out that although only a few cases
have thus far been documented of either seasonal cycles in deep water
or vertical variations which can be correlated with specific water masses,
other instances are likely to arise. Many oceanic areas are subject to
random or seasonal transgressions of water masses. These movements
are not well understood by physical oceanographers, and there are
indications here that properties such as organic carbori and phosphorus
and ratios of major ions may be more sensitive tools for tracing water
mass movement than ordinary T-S relations. Clearly we should move
toward a more inter-disciplinary approach to these problems.
(d) Small-scale variations in distribution. The earlier account of
organic carbon concentrations indicates that there is a large concentration in the surface film and a rapid decrease in the waters immedi-
GORDON A. KILEY
autumn and rapidly rose to a peak in mid-winter. This was followed
by a gradual and irregular decline, with a tendency toward a secondary
maximum in late summer, and then a rapid drop to mid-autumn.
Iselin proposed that an increase in transport would tighten and
deepen the central eddy, and Stommel’s (1948) theory of westward
intensification suggests that an acceleration of the system could move
the position of the centre closer to the Stream. A relatively small shift
in the centre could place Bermuda either in the northward drift between
the centre and the Stream or in the part of the gyre that moves toward
the southwest. Furthermore, expansion and contraction of the central
eddy could involve displacements of deep water throughout the whole
eddy system as well as in the Gulf Stream itself.
This hypothesis provides a framework that can logically contain all
of the fragmentary evidence on seasonal variations of conservative and
non-conservative properties in the Bermuda area. It also provides a
possible reason for a systematic seasonal change which involves only
a slight geographical displacement rather than a profound change in
circulation patterns. However, this is a limited view of a very complex
problem, as will be apparent to anyone who reads Iselin (1940) and
other works involving the broad implications of changes in Gulf Stream
transport. More thorough study is needed, over a broader area, and
until that is done any conclusions are speculatory.
If there is any validity in the hypothesis that has been proposed,
one would suppose that oceanic areas subject to that kind of seasonal
variation would be quite limited. Variations due to intrusions of
particular water masses are likely to be more common. I n the long
range view the Bermuda case may seem trivial, hardly warranting the
present long and diffuse discussion. However, in the present state of
our knowledge a difficult problem such as this one cannot be neglected.
Finally, it should be pointed out that although only a few cases
have thus far been documented of either seasonal cycles in deep water
or vertical variations which can be correlated with specific water masses,
other instances are likely to arise. Many oceanic areas are subject to
random or seasonal transgressions of water masses. These movements
are not well understood by physical oceanographers, and there are
indications here that properties such as organic carbori and phosphorus
and ratios of major ions may be more sensitive tools for tracing water
mass movement than ordinary T-S relations. Clearly we should move
toward a more inter-disciplinary approach to these problems.
(d) Small-scale variations in distribution. The earlier account of
organic carbon concentrations indicates that there is a large concentration in the surface film and a rapid decrease in the waters immedi-