The seasonal pCO2 cycle at 49°N/16.5°W in the northeastern Atlantic Ocean and what it tells us about biological productivity .

Körtzinger, Arne , Send, Uwe, Lampitt, R., Hartman, S., Wallace, Douglas W.R., Karstensen, Johannes , Villagarcia, M.G., Llinas, O. and DeGrandpre, M.D. (2008) The seasonal pCO2 cycle at 49°N/16.5°W in the northeastern Atlantic Ocean and what it tells us about biological productivity . Open Access Journal of Geophysical Research: Oceans, 113 . C04020. DOI 10.1029/2007JC004347.

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Abstract

A 2-year record of mixed layer measurements of CO2 partial pressure (pCO2), nitrate, and other physical, chemical, and biological parameters at a time series site in the northeast Atlantic Ocean (49N/16.5W) is presented. The data show average undersaturation of surface waters with respect to atmospheric CO2 levels by about 40 ± 15 matm, which gives rise to a perennial CO2 sink of 3.2 ± 1.3 mol m2 a1. The seasonal pCO2 cycle is characterized by a summer minimum (winter maximum), which is due to
the dominance of biological forcing over physical forcing. Our data document a rapid transition from deep mixing to shallow summer stratification. At the onset of shallow
stratification, up to one third of the mixed layer net community production during the productive season had already been accomplished. The combination of high
prestratification productivity and rapid onset of tratification appears to have caused the observed particle flux peak early in the season. Mixed layer deepening during fall and winter reventilated CO2 from subsurface respiration of newly exported organic matter,
thereby negating more than one third of the carbon drawdown by net community production in the mixed layer. Chemical signatures of both net community production and respiration are indicative of carbon overconsumption, the effects of which may be restricted, though, to the upper ocean. A comparison of the estimated net community production with satellite-based estimates of net primary production shows fundamental discrepancies in the timing of ocean productivity.

Document Type: Article
Keywords: Chemistry; biological productivity
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
OceanRep > The Future Ocean - Cluster of Excellence
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1029/2007JC004347
ISSN: 2169-9275
Projects: Future Ocean, ANIMATE, MERSEA
Date Deposited: 18 Dec 2008 09:00
Last Modified: 24 Apr 2018 13:19
URI: http://oceanrep.geomar.de/id/eprint/5670

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