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Article
Satellite-Measured Chlorophyll and Temperature Variability Off Northern Chile During the 1996-1998 La Niña and El Niño
Journal of Geophysical Research-Oceans
  • Andrew Thomas, University of Maine - Main
  • J. L. Blanco
  • M. E. Carr
  • P. T. Strub
  • J. Osses
Document Type
Article
Publication Date
1-15-2001
Abstract/ Summary
Time series of satellite measurements are used to describe patterns of surface temperature and chlorophyll associated with the 1996 cold La Nina phase and the 1997-1998 warm El Nino phase of the El Nino - Southern Oscillation cycle in the upwelling region off northern Chile. Surface temperature data are available through the entire study period. Sea-viewing Wide Field-of-view Sensor (SeaWiFS) data first became available in September 1997 during a relaxation in El Nino conditions identified by in situ hydrographic data. Over the time period of coincident satellite data, chlorophyll patterns closely track surface temperature patterns. Increases both in nearshore chlorophyll concentration and in cross-shelf extension of elevated concentrations are associated with decreased coastal temperatures during both the relaxation in El Nino conditions in September-November 1997 and the recovery from EI Nino conditions after March 1998. Between these two periods during austral summer (December 1997 to March 1998) and maximum El Nino temperature anomalies, temperature patterns normally associated with upwelling were absent and chlorophyll concentrations were minimal. Cross-shelf chlorophyll distributions appear to be modulated by surface temperature frontal zones and are positively correlated with a satellite-derived upwelling index. Frontal zone patterns and the upwelling index in 1996 imply an austral summer nearshore chlorophyll maximum, consistent with SeaWiFS data from I 1998-1999, after the El Nino. SeaWiFS retrievals in the data set used here are higher than in situ measurements by a factor of 2-4; however, consistency in the offset suggests relative patterns are valid.
Citation/Publisher Attribution
Thomas AC, Blanco JL, Carr ME, Strub PT, Osses J. Satellite-Measured Chlorophyll and Temperature Variability Off Northern Chile During the 1996-1998 La Nina and El Nino. Journal of Geophysical Research-Oceans. 2001;106: 899-915. To view the published open abstract, go to http://dx.doi.org and enter the DOI.
Publisher Statement
Copyright 2001 American Geophysical Union.
DOI
10.1029/1999JC000052
Version
publisher's version of the published document
Citation Information
Andrew Thomas, J. L. Blanco, M. E. Carr, P. T. Strub, et al.. "Satellite-Measured Chlorophyll and Temperature Variability Off Northern Chile During the 1996-1998 La Niña and El Niño" Journal of Geophysical Research-Oceans Vol. 106 (2001) p. 899 - 915
Available at: http://works.bepress.com/andrew_thomas/11/