BAROTROPIC TIDE AND BAROCLINIC WAVES OBSERVATIONS IN THE RÍO DE LA PLATA ESTUARY,

SIMIONATO, C. G.; MECCIA, V. L.; DRAGANI, W. C.; NUÑEZ, M. N.

JOURNAL OF GEOPHYSICAL RESEARCH

American Geophysical Union

Lugar: Washington D.C., EE.UU.; Año: 2005 vol. 110 p. 1 - 16

0148-0227

The first long-period ADCP series collected in two locations of the salinity front ofthe Rı´o de la Plata estuary are explored for periods less than 30 hours. Barotropic velocityshows tidal and mean currents consistent with what is known about the estuarinecirculation in tidal and seasonal scales. Baroclinic currents provide the first evidence of theoccurrence of internal waves, which can account for half of the total variance. In thenorthernmost location, predominantly zonal oscillations with semidiurnal period, andoscillations with a dominant meridional component and diurnal period, are found.Whereas the first ones can be related to the semidiurnal tide, the second ones seem to beatmospherically forced by the land/sea breeze. In the southernmost location, morerotational oscillations are observed, with periods around the inertial and diurnal ones.Inertial oscillations could result from wind relaxation, whereas diurnal oscillations alsoseem to be forced by breeze. Wave activity in the diurnal band was less frequent in thenorthernmost than in the southernmost location. This can be attributed to less frequentfavorable stratification conditions in that area during the observed period. Wave activity inthe southernmost location resulted weaker during the observed fall than during thesummer. This could be a typical feature given that in autumn both the number of stormsdestroying the thermohaline structure increases and land/sea breeze is less frequent. Thissuggests a likely seasonal cycle in the diurnal wave activity in this area, given that thoseunfavorable conditions are even more marked during winter.