Circulation and salt intrusion in the Piacaguera Channel, Santos (SP)

de Miranda, Luiz Bruner, Olle, Eugenio Dalle, Bergamo, Alessandro Luvizon, dos Santos Silva, Lourval, and Pinheiro Andutta, Fernando (2012) Circulation and salt intrusion in the Piacaguera Channel, Santos (SP). Brazilian Journal of Oceanography, 60 (1). pp. 11-23.

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Abstract

Analysis of thermohaline properties and currents sampled at an anchor station in the Piaçaguera Channel (Santos Estuary) in the austral winter was made in terms of tidal (neap and spring tidal cycles) and non-tidal conditions, with the objective to characterize the stratification, circulation and salt transport due to the fortnightly tidal modulation. Classical methods of observational data analysis of hourly and nearly synoptic observations and analytical simulations of nearly steady-state salinity and longitudinal velocity profiles were used. During the neap tidal cycle the flood (v<0) and ebb (v>0) velocities varied in the range of -0.20 m/s to 0.30 m/s associated with a small salinity variation from surface to bottom (26.4 psu to 30.7 psu). In the spring tidal cycle the velocities increased and varied in the range of -0.40 m/s to 0.45 m/s, but the salinity stratification remained almost unaltered. The steady-state salinity and velocity profiles simulated with an analytical model presented good agreement (Skill near 1.0), in comparison with the observational profiles. During the transitional fortnightly tidal modulation period there was no changes in the channel classification (type 2a - partially mixed and weakly stratified), because the potential energy rate was to low to enhance the halocline erosion. These results, associated with the high water column vertical stability (RiL >20) and the low estuarine Richardson number (RiE=1.6), lead to the conclusions: i) the driving mechanism for the estuary circulation and mixing was mainly balanced by the fresh water discharge and the tidal forcing associated with the baroclinic component of the gradient pressure force; ii) there was no changes in the thermohaline and circulation characteristics due to the forthnigtly tidal modulation; and iii) the nearly steady-state of the vertical salinity and velocity profiles were well simulated with a theoretical classical analytical model.

Item ID: 24066
Item Type: Article (Refereed Research - C1)
Keywords: thermohaline properties; circulation; theoretical-observational profiles; salt transport; stratification
ISSN: 1982-436X
Date Deposited: 04 Dec 2012 06:39
FoR Codes: 04 EARTH SCIENCES > 0405 Oceanography > 040503 Physical Oceanography @ 33%
04 EARTH SCIENCES > 0405 Oceanography > 040501 Biological Oceanography @ 34%
04 EARTH SCIENCES > 0405 Oceanography > 040599 Oceanography not elsewhere classified @ 33%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960503 Ecosystem Assessment and Management of Coastal and Estuarine Environments @ 34%
96 ENVIRONMENT > 9611 Physical and Chemical Conditions of Water > 961102 Physical and Chemical Conditions of Water in Coastal and Estuarine Environments @ 33%
96 ENVIRONMENT > 9611 Physical and Chemical Conditions of Water > 961199 Physical and Chemical Conditions of Water not elsewhere classified @ 33%
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