342
GUN N AR KZJLLENBERG
Profiles of the dye concentration and the temperature structure obtained
with the fiuorometer going down through the layer are used to interpret the
data. When the instrument returns up through the layer the recorded profile
is disturbed since the main body of the instrument passes through the layer
before the sensors.
Although different kinds of distributions were observed in the experiments, they were very similar in nature. In every experiment pulse-formed
layers with very sharp boundaries and almost homogeneous distribution
were found. The thickness of this particular type of layer was virtually
constant over considerable periods of time, and by its form, thickness, and
position in the temperature structure a specific layer can often be identified
and traced with increasing diffusion time. This yields the possibility of determining the vertical mixing intensity, as described by Kullenbcrg (1971). In
general the persistency of the layers is considerable, proving the mixing to be
very weak.
Primary data from the experiments are given in internal reports (Kullenberg et al., 1972; Kullenberg, 1973).
The aim of the present investigation is: (1) to study the connection
between the temperature and dye distributions and to compare the observations from the various areas; (2) to interpret the observed formations of the
dye layers in the light of various possible vertical mixing mechanisms.
THE TRACER DISTRIBUTION IN RELATION TO ‘THE
TEMPERATURE STRUCTURE
In the Sognefjord the tracing was done in the interval 17-30 m, with it
duration of 10-14 hr. The overall temperature distribution showed several
regions with typical small-scak structure separated by rather thick layers
with almost homogeneous temperature. The mean gradients of both temperature and salinity were very weak. After the initial period, the most common
position of the dye layer was in a temperature gradient layer, or in the
transition between an almost homogeneous layer and a sharp gradient. The
dye was apparently trapped on a sheet of locally increased gradient or in
the gradient layer. Only rarely was the dye found in a homogeneous layer,
trapped between sharp gradients. These dye regions seemed to have a relatively small horizontal extent. Examples of profiles (Fig. 2) demonstrate
the pulse-form and the sharp boundaries, as well as the possibility of identifying layers with increasing time. The thickness of the layers varied between
5 and 60 cm, the dominant thickness being 15-20 cm. The thickest layers
were found in locally weak gradient layers or in homogeneous layers. No
multilayered structures were found, only a few indications of a dividing
layer.
GUN N AR KZJLLENBERG
Profiles of the dye concentration and the temperature structure obtained
with the fiuorometer going down through the layer are used to interpret the
data. When the instrument returns up through the layer the recorded profile
is disturbed since the main body of the instrument passes through the layer
before the sensors.
Although different kinds of distributions were observed in the experiments, they were very similar in nature. In every experiment pulse-formed
layers with very sharp boundaries and almost homogeneous distribution
were found. The thickness of this particular type of layer was virtually
constant over considerable periods of time, and by its form, thickness, and
position in the temperature structure a specific layer can often be identified
and traced with increasing diffusion time. This yields the possibility of determining the vertical mixing intensity, as described by Kullenbcrg (1971). In
general the persistency of the layers is considerable, proving the mixing to be
very weak.
Primary data from the experiments are given in internal reports (Kullenberg et al., 1972; Kullenberg, 1973).
The aim of the present investigation is: (1) to study the connection
between the temperature and dye distributions and to compare the observations from the various areas; (2) to interpret the observed formations of the
dye layers in the light of various possible vertical mixing mechanisms.
THE TRACER DISTRIBUTION IN RELATION TO ‘THE
TEMPERATURE STRUCTURE
In the Sognefjord the tracing was done in the interval 17-30 m, with it
duration of 10-14 hr. The overall temperature distribution showed several
regions with typical small-scak structure separated by rather thick layers
with almost homogeneous temperature. The mean gradients of both temperature and salinity were very weak. After the initial period, the most common
position of the dye layer was in a temperature gradient layer, or in the
transition between an almost homogeneous layer and a sharp gradient. The
dye was apparently trapped on a sheet of locally increased gradient or in
the gradient layer. Only rarely was the dye found in a homogeneous layer,
trapped between sharp gradients. These dye regions seemed to have a relatively small horizontal extent. Examples of profiles (Fig. 2) demonstrate
the pulse-form and the sharp boundaries, as well as the possibility of identifying layers with increasing time. The thickness of the layers varied between
5 and 60 cm, the dominant thickness being 15-20 cm. The thickest layers
were found in locally weak gradient layers or in homogeneous layers. No
multilayered structures were found, only a few indications of a dividing
layer.