fCO2 variability at the CARIACO tropical coastal upwelling time series station |
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| Authors: | YM Astor MI Scranton F Muller-Karger R Bohrer J García |
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| Institution: | aFundacion La Salle de Ciencias Naturales, Estación de Investigaciones Marinas de Margarita, Apartado 144 Porlamar, Isla de Margarita, Venezuela;bMarine Sciences Research Center, State University of New York, Stony Brook, NY 11794-5000, United States;cUniversity of South Florida, College of Marine Science, St. Petersburg, FL 33701, United States;dBeach Dr. Apt. 1601, St. Petersburg, FL 33701, United States |
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| Abstract: | Monthly seawater pH and alkalinity measurements were collected between January 1996 and December 2000 at 10°30′N, 64°40′W as part of the CARIACO (CArbon Retention In A Colored Ocean) oceanographic time series. One key objective of CARIACO is to study temporal variability in Total CO2 (TCO2) concentrations and CO2 fugacity (fCO2) at this tropical coastal wind-driven upwelling site. Between 1996 and 2000, the difference between atmospheric and surface ocean CO2 concentrations ranged from about − 64.3 to + 62.3 μatm. Physical and biochemical factors, specifically upwelling, temperature, primary production, and TCO2 concentrations interacted to control temporal variations in fCO2. Air–sea CO2 fluxes were typically depressed (0 to + 10 mmol C m− 2 day− 1) in the first few months of the year during upwelling. Fluxes were higher during June–November (+ 10 to 20 mmol C m− 2 day− 1). Fluxes were generally independent of the slight changes in salinity normally seen at the station, but low positive flux values were seen in the second half of 1999 during a period of anomalously heavy rains and land-derived runoff. During the 5 years of monthly data examined, only two episodes of negative air–sea CO2 flux were observed. These occurred during short but intense upwelling events in March 1997 (−10 mmol C m− 2 day− 1) and March 1998 (− 50 mmol C m− 2 day− 1). Therefore, the Cariaco Basin generally acted as a source of CO2 to the atmosphere in spite of primary productivity in excess of between 300 and 600 g C m− 2 year− 1. |
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| Keywords: | Upwelling fCO2 Air– sea exchange Oceanographic time series Cariaco Basin |
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