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Atmospheric Circulation Changes in the Tropical Pacific
Inferred from the Voyages of the Manila Galleons in the
Sixteenth - Eighteenth Centuries
Bulletin of the American Meteorological Society
Volume 82, Number 11, pp. 2435, November 2001.
Rolando R. Garcia
National Center for Atmospheric Research, Boulder, Colorado
Henry F. Díaz
Climate Diagnostics Center, NOAA, Boulder, Colorado
Ricardo García Herrera
Universidad Complutense, Madrid, Spain
Jon Eischeid
Climate Diagnostics Center, NOAA, Boulder, Colorado
María del Rosario Prieto
CRICYT, Mendoza, Argentina
Emiliano Hernández
Universidad Complutense, Madrid, Spain
Luis Gimeno
Universidad de Vigo, Orense, Spain
Francisco Rubio Durán and Ana María Bascary
Universidad de Sevilla, Seville, Spain
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ABSTRACT:
Historical accounts of the voyages of the Manila galleons derived from the
Archivo General de Indias (General Archive of the Indies, Seville, Spain)
are used to infer past changes in the atmospheric circulation of the
tropical Pacific Ocean. It is shown that the length of the voyage between
Acapulco, Mexico, and the Philippine Islands during the period 1590-1750
exhibits large secular trends, such that voyages in the middle of the
seventeenth century are some 40% longer than those at the beginning or at
the end of the century, and that these trends are unlikely to have been
caused by societal or technological factors. Analysis of a series of
"virtual voyages," constructed from modern wind data, indicates that
sailing time to the Philippines depended critically on the strength
of the trade winds and the position of the western Pacific monsoon trough.
These results suggest that the atmospheric circulation of the western Pacific
underwent large, multidecadal fluctuations during the seventeenth century.
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