M.B. Framiftan . M.P. Etala . E.M. Acha . R. A. Guerrero· C.A. Lasta . O.B. Brown
significantly different from the others at a 99% confidence interval all across the estuary. All the loci of the mean are significantly different from each other close to the
Uruguayan coast, at a level of 90%. The mode loci (Fig. 8.14a) demonstrate the seasonal variability, with the eastward movement of the turbidity fronts at the northern
coast from summer to spring, and the eastward position of the frontal distribution
during spring months.
Summary
A description of the physical characteristics and processes of the Rio de la Plata Estuary is presented based on in situ data, remote sensing information, and modelling.
The large geographical extension and a complex bottom topography, associated with
the existence of shallow banks and channels, play fundamental roles in how. the river
water mixes with the shelf water. Because of the geometry of the estuary, the balance
between atmospheric, tidal and buoyancy forcing varies not only in time, but also in
space. As a result, high temporal-spatial variability is a distinctive attribute of the estuarine processes in the Rio de la Plata.
A brief description of the physiographic setting, climatology and hydrology of the
estuary was presented. Previous studies of tides and tidal currents were reviewed, and
results obtained using a hydro dynamical model were analysed. The effect of atmospheric forcing on the water level in the estuary was discussed and the model outputs
for a case of storm surges was presented. The seasonal distribution of salinity was
described, based on field observations and the analysis of the seasonal cycles of the
atmospheric and river discharge forces. A bimodal pattern is observed in the orientation of the river plume: northeastward during fall/winter and southward, along the
Argentinean coast, during spring/summer. The analysis of vertical salinity sections
shows that a salt-wedge is a quasi-permanent feature at the estuary, however, the stratification may be destroyed by moderate to strong winds. A strong influence of bottom
topography in the estuarine circulation can be inferred from the bottom salinity distribution.
The mean temperature fields in the estuary and the inner shelf are quite homogeneous. The seasonality in temperature is controlled by air-sea heat flux exchange. Some
specifics properties of the surface temperature field, such as fronts and cold water
intrusions, were described using NOAA-AVHRR satellite imagery. A characteristic
feature of the Rio de la Plata is a turbidity maximum located in the transition zone
between the upper and lower estuary. Results of a study of the mean spatial distribution and the seasonality of this turbidity front, based on satellite images, indicate that
the turbidity front has a higher degree of variability at the northern coast. At the southern coast the modal position of the front is related to the 5 m isobath. During summer, the distribution has it innermost location at the northern coast, and during spring,
the frontal distribution is located eastward, and larger values of frontal density are
associated with deeper areas.
Acknowledgements
The authors are very grateful to Dr. C.N.K. Mooers for his encouragement and support during the preparation of this manuscript, and his valuable comments and re-
significantly different from the others at a 99% confidence interval all across the estuary. All the loci of the mean are significantly different from each other close to the
Uruguayan coast, at a level of 90%. The mode loci (Fig. 8.14a) demonstrate the seasonal variability, with the eastward movement of the turbidity fronts at the northern
coast from summer to spring, and the eastward position of the frontal distribution
during spring months.
Summary
A description of the physical characteristics and processes of the Rio de la Plata Estuary is presented based on in situ data, remote sensing information, and modelling.
The large geographical extension and a complex bottom topography, associated with
the existence of shallow banks and channels, play fundamental roles in how. the river
water mixes with the shelf water. Because of the geometry of the estuary, the balance
between atmospheric, tidal and buoyancy forcing varies not only in time, but also in
space. As a result, high temporal-spatial variability is a distinctive attribute of the estuarine processes in the Rio de la Plata.
A brief description of the physiographic setting, climatology and hydrology of the
estuary was presented. Previous studies of tides and tidal currents were reviewed, and
results obtained using a hydro dynamical model were analysed. The effect of atmospheric forcing on the water level in the estuary was discussed and the model outputs
for a case of storm surges was presented. The seasonal distribution of salinity was
described, based on field observations and the analysis of the seasonal cycles of the
atmospheric and river discharge forces. A bimodal pattern is observed in the orientation of the river plume: northeastward during fall/winter and southward, along the
Argentinean coast, during spring/summer. The analysis of vertical salinity sections
shows that a salt-wedge is a quasi-permanent feature at the estuary, however, the stratification may be destroyed by moderate to strong winds. A strong influence of bottom
topography in the estuarine circulation can be inferred from the bottom salinity distribution.
The mean temperature fields in the estuary and the inner shelf are quite homogeneous. The seasonality in temperature is controlled by air-sea heat flux exchange. Some
specifics properties of the surface temperature field, such as fronts and cold water
intrusions, were described using NOAA-AVHRR satellite imagery. A characteristic
feature of the Rio de la Plata is a turbidity maximum located in the transition zone
between the upper and lower estuary. Results of a study of the mean spatial distribution and the seasonality of this turbidity front, based on satellite images, indicate that
the turbidity front has a higher degree of variability at the northern coast. At the southern coast the modal position of the front is related to the 5 m isobath. During summer, the distribution has it innermost location at the northern coast, and during spring,
the frontal distribution is located eastward, and larger values of frontal density are
associated with deeper areas.
Acknowledgements
The authors are very grateful to Dr. C.N.K. Mooers for his encouragement and support during the preparation of this manuscript, and his valuable comments and re-