Preliminary results of drift-bottle releases and recoveries in the Western Tropical Atlantic

Preliminary results of drift-bottle releases and recoveries in the Western Tropical Atlantic

Ellen F. Luedemann

Instituto Oceanográfico da Universidade de São Paulo

SYNOPSIS

In February-March 1963, during the Equalant Operation for the ICITA program, 476 drift-bottles were released at the equatorial waters off the northern Brazilian coast (01ºS to 09ºN and 043ºW to 053ºW). Thirty-five, bottles were recovered (7,4%). Those were classed in five groups according to their different velocity ranges and areas of recovery (Trinidad Island; Lesser Antilles; Caribbean and Florida area; north Brazil; northeastern Brazil).

The recoveries of bottles released within 300 nm off the northern and northeastern coast of Brazil confirmed a strong current along the north and northeast coast in northwestern direction (South Equatorial Current and branches). In late February-early March the bottles showed maximum velocities of this current (3,6 knots).

The region off the northern coast of Brazil, between 05ºN and 09ºN up to 050ºW seems to have been under the influence of an eastward component of the surface current in this same period, while at late March this influence appears to have been weaker. In the region from Trinidad Island to Yucatan Peninsula the current seems to be stronger on the northeastern side of the Caribbean Sea.

SUMÁRIO

Em fevereiro-março de 1963 foram lançadas 476 garrafas de deriva diante das costas norte e nordeste do Brasil durante a Operação Equalant para o programa ICITA; destas foram recuperadas até agora 35.

Estas foram classificadas em cinco grupos conforme a sua área de encontro e segundo as variações de velocidade do percurso.

GRUPO I - Ilha de Trinidad - As garrafas recuperadas apresentavam variações de velocidade entre 20,8 a 87,16 mn/24 h com um valor médio de 52,0 mn por dia ou 2,2 nós (Tab. I).

GRUPO II - As pequenas Antilhas - A velocidade das garrafas recuperadas variaram de 10,3 mn por dia a 25 mn por dia. O valor médio esteve ao redor de 17,55 mn por dia ou 0,73 nós (Tab. II).

GRUPO III - Mar dos Caraibas e Florida - Este grupo compreende garrafas que aparentemente acompanharam as Correntes das Caraíbas e da Flórida com velocidades que variaram de 4,14 mn por dia a 20 mn por dia com uma velocidade média de 10,8 mn por dia ou 0,44 nós (Tab. III). Cerca de 50% dessas garrafas convergiram para a área da Flórida enquanto que outras foram encontradas em diferentes locais do Mar dos Caraíbas (Tab. III).

GRUPO IV - Norte do Brasil - Compreende as garrafas lançadas diante das desembocaduras dos rios Pará E Amazonas. As garrafas que chegaram ao Maranhão, da estação 40, apresentaram uma velocidade entre 0,66 mn por dia (151 dias no mar) E 10,0 mn por dia e foram as únicas que derivaram em direção sudeste. As velocidades das garrafas encontradas no Amapá, lançadas nas estações 18 e 20, representam os valores mais baixos de todos, variando entre 0,29 mn por dia a 4,4 mn por dia (Tab. IV).

GRUPO V - Nordeste do Brasil - As garrafas foram lançadas durante o cruzeiro de retorno diante das costas do nordeste do Brasil. A variação de velocidade deste grupo vai de 7,6 mn por dia para 11,0 mn por dia, com um valor médio de 9,0 mn por dia ou 0,4 nós (Tab. V).

Com exceção das garrafas da estação 40 que derivaram em direção sudeste, todas as outras foram encontradas a noroeste do seu local de lançamento.

Full text available only in PDF format.

Texto completo disponível apenas em PDF.

ACKNOWLEDGEMENTS

I would like to express here my gratitude to Dr. OLA M. JOHANNESSEN under whose supervision this paper was done. Thanks are due to Dr. INGVAR EMÍLSSON, the scientist in charge during the Equalant I Operation, who organized all the work concerning the release of bottles and for permitting the use of the present data. The work at sea was executed by members of the staff of the Physical Section, and by the officers and the crew of the "CT Bertioga". I am much indebted also to Dr. LILIANA FORNERIS for worthful advices and helpful criticism. To Dr. ARGEO MAGLIOCCA, Director of the Physical Division, my thanks for facilities given. Many thanks are due to the Director of the Institute, Dr. MARTA VANNUCCI , for criticisms and reading of the manuscript. I wish to extend my thanks also to Dr. REIDAR LEINEBÖ for his kind appreciation and helpful suggestion. The drawings were made by Mr. RENATO HERZ.

REFERENCES

COCHRANE, J. D. 1963. Equatorial undercurrent and related currents off Brazil in March and April, 1963. Science, vol. 142, n.º 3593, p. 669-671.

DIETRICH, G. 1939. Das amerikanische Mittelmeer. Z. Ges. Erdk. Berl., p. 108-130. Cit. in Sverdrup, H. U. et al. The oceans, p. 642.

DIETRICH, G. & KALLE, K. 1957. Allgemeine Meereskunde. Berlin, Gebrüder, Bornträger.

HERNANDEZ, Y. S. 1960. Tratado de meteorologia nautica. Barcelona, Garriga, 475 p.

KARWOSKI, J. 1963. Measurement of sea currents by means of drift bottles. Int. hydrogr. Rev., vol. XL, n.º 2, p. 119-123.

KEEN, J. & CHIMIAK, W. 1955. Caribbean current survey. Tech. Rep. hydrogr. Off., Wash. Tr-12, 14 p.

NEUMANN , G. 1960. Evidence for an equatorial undercurrent in the Atlantic Ocean. Deep Sea Res., vol. 6, n.º 4, p. 328-334.

NEUMANN , G. 1965. Ocanography of the tropical Atlantic. Anais Acad. bras. Cienc, vol. 37, supl., p. 63-82.

PARR, A. E. 1937. A contribution to the hydrography of the Caribbean and Cayman seas based upon the observations made by the research ship "Atlantis", 1933-34. Bull. Bingham oceanogr. Coll., vol. 5, art. 4, 110 p. Cit. in Sverdrup, H. W., et al., The Oceans, p. 641.

RODEN, G. I. 1962. On sea-surface temperature, cloudiness and wind variations in the Tropical Atlantic. J. Atmos. Sci., vol. 19, n.º 1, p. 68.

SVERDRUP, H. U., JOHNSON, M. W., FLEMING , R. H. 1955. The Oceans. 6th ed. New Jersey, Prentice Hall.

U. S.-NAVY HYDROGRAPHIC OFFICE 1958. Atlas of pilot charts of the South Atlantic Ocean and Central American Waters. H. O. Publ. n.º 106, 16 p. 2nd edition, Washington.

(Received in 25/10/1966)

Publ. n.º 241 do Inst. Ocean. da USP.

• COCHRANE, J. D. 1963. Equatorial undercurrent and related currents off Brazil in March and April, 1963. Science, vol. 142, n.ş 3593, p. 669-671.
• DIETRICH, G. 1939. Das amerikanische Mittelmeer. Z. Ges. Erdk. Berl., p. 108-130.
• DIETRICH, G. & KALLE, K. 1957. Allgemeine Meereskunde. Berlin, Gebrüder, Bornträger.
• HERNANDEZ, Y. S. 1960. Tratado de meteorologia nautica. Barcelona, Garriga, 475 p.
• KARWOSKI, J. 1963. Measurement of sea currents by means of drift bottles. Int. hydrogr. Rev., vol. XL, n.ş 2, p. 119-123.
• KEEN, J. & CHIMIAK, W. 1955. Caribbean current survey. Tech. Rep. hydrogr. Off., Wash. Tr-12, 14 p.
• NEUMANN , G. 1960. Evidence for an equatorial undercurrent in the Atlantic Ocean. Deep Sea Res., vol. 6, n.ş 4, p. 328-334.
• NEUMANN , G. 1965. Ocanography of the tropical Atlantic. Anais Acad. bras. Cienc, vol. 37, supl., p. 63-82.
• PARR, A. E. 1937. A contribution to the hydrography of the Caribbean and Cayman seas based upon the observations made by the research ship "Atlantis", 1933-34. Bull. Bingham oceanogr. Coll., vol. 5, art. 4, 110 p.
• Cit. in Sverdrup, H. W., et al., The Oceans, p. 641.
• RODEN, G. I. 1962. On sea-surface temperature, cloudiness and wind variations in the Tropical Atlantic. J. Atmos. Sci., vol. 19, n.ş 1, p. 68.
• SVERDRUP, H. U., JOHNSON, M. W., FLEMING , R. H. 1955. The Oceans. 6th ed. New Jersey, Prentice Hall.
• U. S.-NAVY HYDROGRAPHIC OFFICE 1958. Atlas of pilot charts of the South Atlantic Ocean and Central American Waters. H. O. Publ. n.ş 106, 16 p. 2nd edition, Washington.

Publication Dates

• Publication in this collection
  14 June 2012
• Date of issue
  1967

History

• Received
  25 Oct 1966