Geoscience Reference
In-Depth Information
Laboratory Modeling of Buoyant
Jet in a Rotating Fluid
Natalya Demchenko
1
Introduction
It is known that the bottom topography significantly influences the dynamics
and structure of thermal fronts in the freshwater basins and brackish seas. Field
observations of the thermally induced fronts in the Baltic Sea during spring heating
have revealed that large-scale fronts in the southern and central Baltic are aligned
with the coasts and isobaths; significant correlation between the sea-surface tem-
perature and topography was found (Bychkova et al.
1987
). This was corroborated
also by an analysis of 9-month time series of infrared imagery in the northern and
central Baltic (Kahru et al.
1995
) In some regions of the Ladoga Lake, nonuniform
topography leads to the deceleration of thermal bar (frontal zone, associated
with the temperature of maximum density,
Tmd
3.98
C) and formation of the
“secondary” thermal front, marked by 5
C-isotherm at the surface, with very sharp
temperature gradients in the upper layers (Naumenko and Karetnikov
1993
). Also,
there are natural observations and laboratory and theoretical studies of the effects of
Earth rotation on the vertical and horizontal convection in the ocean and atmo-
sphere (Boubnov and Golitsyn
1995
) showing the importance of these effects for
geophysical convective flows.
The main goal of this work is to investigate, in the rotating laboratory tank with a
sloping and horizontal bottom, how the Coriolis force and bottom topography
influence the propagation of the surface warm buoyant jet in fresh water layer - a
qualitative manifestation of the “late” stage of the thermal bar phenomenon in lakes
and marginal seas (Demchenko and Chubarenko
2007
).
