PARTICULATE ORGANIC MATTER IN SEA WATER
23
The measurements ended too soon to determine the length of the
period when the water was drifting south. Nor is there any assurance
that this kind of event occurs every year or in deep water as well as
the surface layer, However, there is evidence of an indirect sort that
a flow from the south is re-established by early spring. Some years
ago the writer attempted to calculate coefficients of vertical eddy
conductivity based upon temperature data taken in the vicinity of
Bermuda. These were to be used for computations of biological rates
of change of essential micronutrients. The attempt failed because
temperature increases in waters underlying the surface layer were Iarger
than the solar input during the spring and early summer and were
patently the result of advection of warmer water from the south, so
that the problem could not be treated in simple terms of vertical
transfer.
A hypothesis can be proposed that there is a net northward transport of water past Bermuda during most of the year, with a short
period of reversal in winter, and that this is a generalized phenomenon
involving the whole water column. This hypothesis does not violate
any of the information available, although admittedly the evidence is
tenuous. Furthermore, a movement of this sort, which is distributed
through the water column rather than involving intrusions of particular
water masses, probably is indicative of a change in major circulation
patterns in that part of the Atlantic Ocean.
Iselin (1936) and Sverdrup et al. (1942) noted that Gulf Stream
transport increases northward toward the New England offing and
decreases thereafter. Principles of mass continuity are best satisfied
by a theory that all of the Sargasso Sea is in a state of slow, clockwise
motion around a central high that is located far toward the northwestern edge of the area. Sverdrup’s transport diagram shows about
a tenth of the Gulf Stream water peeling off in a tight little gyre in
the vicinity of Bermuda.
This was only a diagrammatic sketch, which was drawn without any
real knowledge of the trajectory of the water past Bermuda, and it
merely serves as a reminder that the Sargasso Sea is an integral part
of the eddy rather than dead water within the encircling currents of
the North Atlantic gyre. The actual geometry of the system can be
expected to change with variations in Gulf Stream transport.
Iselin (1940) analyscd all of the information available at that time
which had a bearing on transport variations in the Gulf Stream.
There was clear evidence of systematic seasonal variations. His compilation of geostrophic computations and tide gauge records from
Miami and Charleston showed that transport was minimal in mid-
23
The measurements ended too soon to determine the length of the
period when the water was drifting south. Nor is there any assurance
that this kind of event occurs every year or in deep water as well as
the surface layer, However, there is evidence of an indirect sort that
a flow from the south is re-established by early spring. Some years
ago the writer attempted to calculate coefficients of vertical eddy
conductivity based upon temperature data taken in the vicinity of
Bermuda. These were to be used for computations of biological rates
of change of essential micronutrients. The attempt failed because
temperature increases in waters underlying the surface layer were Iarger
than the solar input during the spring and early summer and were
patently the result of advection of warmer water from the south, so
that the problem could not be treated in simple terms of vertical
transfer.
A hypothesis can be proposed that there is a net northward transport of water past Bermuda during most of the year, with a short
period of reversal in winter, and that this is a generalized phenomenon
involving the whole water column. This hypothesis does not violate
any of the information available, although admittedly the evidence is
tenuous. Furthermore, a movement of this sort, which is distributed
through the water column rather than involving intrusions of particular
water masses, probably is indicative of a change in major circulation
patterns in that part of the Atlantic Ocean.
Iselin (1936) and Sverdrup et al. (1942) noted that Gulf Stream
transport increases northward toward the New England offing and
decreases thereafter. Principles of mass continuity are best satisfied
by a theory that all of the Sargasso Sea is in a state of slow, clockwise
motion around a central high that is located far toward the northwestern edge of the area. Sverdrup’s transport diagram shows about
a tenth of the Gulf Stream water peeling off in a tight little gyre in
the vicinity of Bermuda.
This was only a diagrammatic sketch, which was drawn without any
real knowledge of the trajectory of the water past Bermuda, and it
merely serves as a reminder that the Sargasso Sea is an integral part
of the eddy rather than dead water within the encircling currents of
the North Atlantic gyre. The actual geometry of the system can be
expected to change with variations in Gulf Stream transport.
Iselin (1940) analyscd all of the information available at that time
which had a bearing on transport variations in the Gulf Stream.
There was clear evidence of systematic seasonal variations. His compilation of geostrophic computations and tide gauge records from
Miami and Charleston showed that transport was minimal in mid-