Variability of the Thermohaline Field in a Large Tropical, Well-Mixed Estuary: the Influence of an Extreme Draught Event

Lessa, Guilherme C.; Mariani, Rafael; Fonseca, Lucas Furtado da

doi:10.1007/s12237-019-00641-y

Cited by 5 publications

(7 citation statements)

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“…Vertical CTD profiles were executed simultaneously with a SeaBird SBE19Plus to be used as a reference for the moored sensors. The downloaded data underwent quality control check where spurious data were eliminated and offsets and drifts (due to biofouling) were corrected (see Lessa et al 2019 for detailed information on the data processing). Salinity was calculated with the aid of Matlab SEAWATER (Copyright © CSIRO, Phil Morgan, 1994) routines.…”

Section: Salinity Datamentioning

confidence: 99%

“…Twelve of these campaigns were carried out during spring slack-low tides (profiling at P1, P4, and P7) and 24 campaigns during neap slack-high tide (profiling all 6 stations). Further details on these campaigns are provided by Lessa et al (2019). The following statistical indexes were used to validate the model results: bias, root mean squared error (RMSE), scatter index, and Pearson's correlation coefficient.…”

Section: Salinity Datamentioning

confidence: 99%

“…BTS regions originally shallower than 5 m, whose depths were altered (deepened) in the model, were excluded from the above sectorization. The bay's sectorization aimed to define a few sectors along the main estuarine axis based on longitudinal salinity gradients observed in the 36 vertical CTD profiles as reported by Lessa et al (2019). We also isolated main indentations inside the bay with more restrict water circulation.…”

Section: Mean Bts Salinity and Estimates Of Past Conditionsmentioning

confidence: 99%

“…Evaporation data is, unfortunately, not provided. According to the method described by Lessa et al (2019), the atmospheric water volume falling directly on the bay surface was calculated by multiplying the area of influence of each isohyet (Fig. 1C) by its month-total rainfall calculated on the basis of the observed rainfall gradient between SSA and CRZ and the distance of each isohyet to SSA.…”

Section: Freshwater Discharge and Meteorological Datamentioning

confidence: 99%

“…Todos os Santos Bay (BTS) is the southernmost estuary of the Brazilian northeast. Freshwater inflow to the estuary has undergone a long-term declining trend, and a peculiar hypersaline condition was recently documented by Lessa et al (2019). The BTS is the third largest Brazilian estuary where the drainage of a catchment area over 60 × 10 3 km 2 (twice the size of Hudson River or 1.2 times larger than Weser watersheds) is vital to maintain an estuarine circulation during the dry season on the coast (Santana et al 2018).…”

Section: Introductionmentioning

confidence: 99%

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Long-term Variability of the Salinity Field in a Large Tropical, Well-Mixed Estuary: the Influence of Climatic Trends

Mariani

Lessa

Marta‐Almeida

2021

Estuaries and Coasts

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This work investigates the impact of regional climatic changes upon the salinity field of Todos os Santos Bay (BTS), the third largest estuary in the country. A comprehensive meteorological and oceanographic data set was used, which included more than 50 years of rainfall, river discharge and air temperature, 7 years of hydrodynamic numerical simulations of the bay and adjacent shelf, and 3 years of observations of the salinity field. The results show a clear aridification (less humidity and warmer air temperatures) trend in the last 5-6 decades. In this period, the yearly mean fluvial discharges and total rainfall were reduced by up to 72% and 50%, respectively, of their climatological means, and the air temperature increased by up to 1.25 °C. Less freshwater inflow and higher temperatures caused an increase of the mean surface salinity of 0.6 for the whole bay and 1.2 in the most internal sectors. Hypersalinity events apparently occurred for the first time in the early 1990s, and reached a maximum intensity in 2013 during the worst regional draught in the historical record, when an estuarine density plug was observed. The hypersalinity events were intensified, and not caused by the damming of Paraguaçu River, whose summer discharges have decreased faster than anticipated by previous investigations. The original tropical climate of the region has become more Mediterranean, with relatively less rainfall occurring in the summer. The hydrographic changes of the BTS exemplify similar hydrological and hydrographic processes that might also be underway in tropical areas undergoing climate aridification.

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Section: Salinity Datamentioning

confidence: 99%

Section: Salinity Datamentioning

confidence: 99%

Section: Mean Bts Salinity and Estimates Of Past Conditionsmentioning

confidence: 99%

Section: Freshwater Discharge and Meteorological Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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