Hydrographic structure of the continental shelf in Santos Basin and its causes: The SANAGU and SANSED campaigns (2019)

Authors

  • Marcelo Dottori
  • Dalton K. Sasaki
  • Danilo A. Silva
  • Sergio R. Del–Giovannino
  • Andressa P. Pinto
  • Magnim Gnamah
  • Arian D. Santos
  • Ilson C. A. da Silveira
  • Wellington C. Belo
  • Renato P. Martins
  • Daniel L. Moreira

DOI:

https://doi.org/10.1590/

Keywords:

Water Mass, Tropical Water, South Atlantic Central Water, Wind Impulse, Salinity, Continental Runoff

Abstract

This study describes the hydrography and water masses of the Santos Basin Continental Shelf (SBCS) during two hydrographic campaigns (SANAGU, SANSED) in 2019. Coastal Water (CW) is the dominant water mass in the southern portion of the SBCS, with relatively low salinity values (S<35.5 g kg–1), and satellite data show that local precipitation and river discharge could not account for the low salinity observed during the cruises in the southern region of the domain. The low salinity observed is explained by the transport from the south influenced by Subtropical Shelf Water (STSW), which was influenced by the La Plata River discharge. In the northern region of the SBCS, the South Atlantic Central Water (SACW) dominates the bottom layers of the water column, with the wind playing a major role in the uplift of this water mass, as evidenced by a wind impulse analysis. In this part of the shelf, Tropical Water (TW) was the second water mass in volume and occupied the surface layers and offshore the shelf. CW is restricted to a thin surface layer, which reaches distances of a few kilometers from the coast. Our analysis show the differences in the hydrographic structure of the SBCS and suggests that the SBCS can be divided in two regions with distinct characteristics: 1) the area southwest of São Sebastião, where the hydrographic parameters were modulated by the presence of the Subtropical Shelf Water (STSW); 2) the area northeast of São Sebastião, where the uplifting of SACW was the dominant process.

References

BRETHERTON, F. P., DAVIS, R. E. & FANDRY, C. 1976. A technique for objective analysis and design of oceanographic experiments applied to mode-73, Deep Sea Research and Oceanographic Abstracts, Vol. 23, Elsevier, pp. 559–582.

CALADO, L., DA SILVEIRA, I., GANGOPADHYAY, A. & DE CASTRO, B. 2010. Eddy-induced upwelling off cape São Tomé (22°S, Brazil), Continental Shelf Research 30(10-11): 1181–1188.

CAMPOS, E. J. D., VELHOTE, D. & DA SILVEIRA, I. C. A. 2000. Shelf break upwelling driven by Brazil Current cyclonic meanders, Geophysical Research Letters 27: 751–754.

CARTER, E. F. & ROBINSON, A. R. 1987. Analysis models for the estimation of oceanic fields, Journal of Atmospheric and Oceanic Technology 4(1): 49–74.

CASTRO, B. D. & MIRANDA, L. D. 1998a. Physical oceanography of the western Atlantic continental shelf located between 4° N and 34° S, The Sea 11(1): 209–251.

CASTRO, B. & MIRANDA, L. 1998b. Hydrographic properties in the São Sebastião channel: Daily variations observed in March, 1980, Revista Brasileira de Oceanografia 46(2): 111–123.

CASTRO, B. M. 2014. Summer/winter stratification variability in the central part of the South Brazil Bight, Continental Shelf Research 89: 15–23.

CASTRO, B. M. & LEE, T. N. 1995. Wind-forced sea level variability on the southeast Brazilian shelf, J. Geophys. Res. 100(C8): 16,045–16,056.

CASTRO, B. M., MIRANDA, L. B., SILVA, L. S., FONTES, R. F. C. ., PEREIRA, A. F. & COELHO, A. L. 2008. Processos físicos: Hidrografia, circulação e transporte, EDUSP.

CERDA, C. & CASTRO, B. M. 2014. Hydrographic climatology of South Brazil Bight shelf waters between Sao Sebastiao (24°S) and Cabo Sao Tome (22°S), Continental Shelf Research 89: 5–14.

CSANADY, G. 1977. Intermittent ‘full’ upwelling in Lake Ontario, Journal of Geophysical Research 82(3): 397–419.

DONLON, C. J., MARTIN, M., STARK, J., ROBERTS-JONES, J., FIEDLER, E. & WIMMER, W. 2012. The operational sea surface temperature and sea ice analysis (OSTIA) system, Remote Sensing of Environment 116: 140–158.

DOTTORI, M. & CASTRO, B. M. 2009. The response of the São Paulo continental shelf, Brazil, to synoptic winds, Ocean Dynamics 59(4): 603–614.

DOTTORI, M. & CASTRO, B. M. 2018. The role of remote wind forcing in the subinertial current variability in the central and northern parts of the South Brazil Bight, Ocean Dynamics 68(6): 677–688.

ETCHEVERRY, L. R., SARACENO, M., PIOLA, A. R., VALLADEAU, G. & MÖLLER, O. 2015. A comparison of the annual cycle of sea level in coastal areas from gridded satellite altimetry and tide gauges, Continental shelf research 92: 87–97.

FERNANDES, F. 2014. python-ctd v0.2.1. URL: https://doi.org/10.5281/zenodo.11396 (visited on December 16th 2022)

» https://doi.org/10.5281/zenodo.11396

GARREAUD, R. 2000. Cold air incursions over subtropical South America: Mean structure and dynamics, Monthly Weather Review 128(7): 2544–2559.

GOOD, S., FIEDLER, E., MAO, C., MARTIN, M. J., MAYCOCK, A., REID, R., ROBERTS-JONES, J., SEARLE, T., WATERS, J., WHILE, J. ET AL. 2020. The current configuration of the OSTIA system for operational production of foundation sea surface temperature and ice concentration analyses, Remote Sensing 12(4): 720.

HERSBACH, H., BELL, B., BERRISFORD, P., HIRAHARA, S., HORÁNYI, A., MUÑOZSABATER, J., NICOLAS, J., PEUBEY, C., RADU, R., SCHEPERS, D. ET AL. 2020. The ERA5 global reanalysis, Quarterly Journal of the Royal Meteorological Society 146(730): 1999–2049.

LODER, J. W., BOICOURT, W. C. & SIMPSON, J. H. 1998. Western ocean boundary shelves coastal segment (w), The Sea 11: 3–27.

MAHIQUES, M. M. D., BURONE, L., FIGUEIRA, R. C. L., LAVENÉRE-WANDERLEY, A. A. D. O., CAPELLARI, B., ROGACHESKI, C. E., BARROSO, C. P., DOS SANTOS, S., AUGUSTO, L., CORDERO, L. M. ET AL. 2009. Anthropogenic influences in a lagoonal environment: a multiproxy approach at the Valo Grande mouth, Cananéia-Iguape system (SE Brazil), Brazilian Journal of Oceanography 57(4): 325–337.

MAMAYEV, O. I. 1975. Temperature-salinity analysis of world ocean waters, Elsevier.

MARTA-ALMEIDA, M., DALBOSCO, A., FRANCO, D. & RUIZ-VILLARREAL, M. 2021. Dynamics of river plumes in the South Brazilian Bight and South Brazil, Ocean Dynamics 71: 59–80.

MCDOUGALL, T. J. & BARKER, P. M. 2011. Getting started with TEOS-10 and the gibbs seawater (GSW) oceanographic toolbox, Scor/Iapso WG 127: 1–28.

MEISSNER, T., F. J. W. A. M. R. L. 2019. Remote sensing systems SMAP ocean surface salinities [level 2C, level 3 running 8-day, level 3 monthly], version 4.0 validated release. URL: Available online at https://www.remss.com/missions/smap (visited on December 16th 2022)

» https://www.remss.com/missions/smap

MÖLLER JR, O. O., PIOLA, A. R., FREITAS, A. C. & CAMPOS, E. J. 2008. The effects of river discharge and seasonal winds on the shelf off southeastern South America, Continental shelf research 28(13): 1607–1624.

MORAIS, P. H. L. S. 2016. Hidrodinâmica da plataforma continental interna do estado de São Paulo, Master’s thesis, Universidade de São Paulo. URL: https://teses.usp.br/teses/disponiveis/21/21135/tde-24022017-181654/pt-br.php (visited on December 16th 2022)

» https://teses.usp.br/teses/disponiveis/21/21135/tde-24022017-181654/pt-br.php

PALÓCZY, A., DA SILVEIRA, I., CASTRO, B. & CALADO, L. 2014. Coastal upwelling off Cape São Tomé (22° S, Brazil): The supporting role of deep ocean processes, Continental Shelf Research 89: 38–50.

PIMENTA, F. M., CAMPOS, E. J. D., MILLER, J. L. & PIOLA, A. R. 2005. A numerical study of the Plata River plume along the southeastern South American continental shelf, Brazilian Journal of Oceanography 53(3-4): 129–146.

PIOLA, A. R., CAMPOS, E. J., MÖLLER JR, O. O., CHARO, M. & MARTINEZ, C. 2000. Subtropical shelf front off eastern South America, Journal of Geophysical Research: Oceans 105(C3): 6565–6578.

PIOLA, A. R., MATANO, R. P., PALMA, E. D., MÖLLER, O. O. & CAMPOS, E. J. 2005. The influence of the Plata River discharge on the western South Atlantic shelf, Geophysical Research Letters 32(1).

RODRIGUES, R. R. & WOOLLINGS, T. 2017. Impact of atmospheric blocking on South America in austral summer, Journal of Climate 30(5): 1821–1837.

SILVA, D. A. & DOTTORI, M. 2021. The atmospheric blocking influence over the South Brazil Bight during the 2013–2014 summer, Regional Studies in Marine Science 45: 101815.

SILVEIRA, I. C. A. D., SCHMIDT, A. C. K., CAMPOS, E. J. D., DE GODOI, S. S. & IKEDA, Y. 2000. A Corrente do Brasil ao largo da costa leste brasileira, Rev. Bras. Ocean 48: 171–183.

STARK, J. D., DONLON, C. J., MARTIN, M. J. & MCCULLOCH, M. E. 2007. OSTIA: An operational, high resolution, real time, global sea surface temperature analysis system, Oceans 2007-europe, IEEE, pp. 1–4.

VALLA, D., PIOLA, A. R., MEINEN, C. S. & CAMPOS, E. 2018. Strong mixing and recirculation in the northwestern Argentine basin, Journal of Geophysical Research: Oceans 123(7): 4624–4648.

Downloads

Published

29.03.2023

How to Cite

Hydrographic structure of the continental shelf in Santos Basin and its causes: The SANAGU and SANSED campaigns (2019). (2023). Ocean and Coastal Research, 71(Suppl. 3). https://doi.org/10.1590/