Temporal variations of temperature, salinity and circulation in the Peruipe river estuary (nova Vicosa, BA)

Andutta, Fernando Pinheiro, de Miranda, Luiz Bruner, Schettini, Carlos Augusto Franca, Siegle, Eduardo, da Silva, Mario Pereira, Izumi, Vitor Massaki, and Chagas, Felipe Murai (2013) Temporal variations of temperature, salinity and circulation in the Peruipe river estuary (nova Vicosa, BA). Continental Shelf Research, 70. pp. 36-45.

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Abstract

Eulerian profiles of thermohaline properties and currents have been sampled in the Peruípe River Estuary (Nova Viçosa, BA),southern region of the Caravelas-Peruípe Rivers Estuarine System. One station was located near the mouth (C) and other one up the estuary (E).The Hansen–Rattraydiagram classification of the upper reaches of the Peruípe river estuary in the wet season changed from Type 2b (partially mixed and highly stratified—ν=0.88) to Type 1b (highly stratified—ν∼1.00) due to the fortnightly tidal modulation. This region was mainly forced by river discharge (RiE=5.7 and RiE=4.1) and characterized by high (RiL>20) and low stabilities (RiL<20) in the neap and spring tidal cycles. However, near the mouth stratification was strongly modulated by the tide, and its classification alternates from being highly stratified (Type 2b—ν=0.92) in the neap tide to being well mixed with low stratification (Type1a—ν=1.00); the mouth was dominated by fresh water discharge (RiE=12.9) and tidal stirring (RiE=0.6) in the neap and spring tide, respectively, and were associated with high and low stabilities. The classical steady-state salinity and velocity profiles show good agreement (Skill∼1.0) with the corresponding observational profiles when simulated with a classical analytical model. The main characteristics of the nearly steady-state bidirectional (with a weak barolinic signal) and unidirectional velocity profiles were in good agreement with the estuarine quantitative classifications (Types2b,1a and 1b). The rate of change of the potential energy due to fortnightly tidal modulation was slightly higher near the mouth (6.1Jm⁻³ s⁻¹) than in the upper reaches of the estuary(5.2Jm⁻³ s⁻¹). However, this was not strong enough to generate halocline erosion in the transitional neap to spring tidal cycle, and the estuary classification remained Type 1b. The main conclusions are summarized as follows: (i) Two stations sampled along the Peruípe river estuary gave reasonable insight into its main thermohaline, circulation and salt transport characteristics; (ii) The well-known changes in classification along an estuarine channel were confirmed for the Peruípe estuary; (iii) During the fortnightly tidal modulation (neap to the spring tidal cycle) an increase in the salt transport down the estuary was observed; (iv)Data fitting showed that the best results of the analytical model were obtained using the time-depth mean velocity, instead of the estimated velocity generated by the freshwater discharge.

Item ID: 27230
Item Type: Article (Refereed Research - C1)
Keywords: thermohaline properties; circulation; observational and theoretical profiles; salt transport; periodic stratification and potential energy
ISSN: 1873-6955
Date Deposited: 29 May 2013 00:00
FoR Codes: 04 EARTH SCIENCES > 0405 Oceanography > 040503 Physical Oceanography @ 50%
04 EARTH SCIENCES > 0405 Oceanography > 040599 Oceanography not elsewhere classified @ 50%
SEO Codes: 96 ENVIRONMENT > 9699 Other Environment > 969902 Marine Oceanic Processes (excl. Climate Related) @ 50%
97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 50%
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