Inter-annual variability of the carbon dioxide oceanic sink south of Tasmania
International audience We compiled a large data-set from 22 cruises spanning from 1991 to 2003, of the partial pressure of CO 2 (pCO 2 ) in surface waters over the continental shelf (CS) and adjacent open ocean (43° to 46° S; 145° to 150° E), south of Tasmania. Sea surface temperature (SST) anomalie...
Published in: | Biogeosciences |
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Main Authors: | , , , , |
Other Authors: | , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2007
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Subjects: | |
Online Access: | https://hal.archives-ouvertes.fr/hal-00330273 https://hal.archives-ouvertes.fr/hal-00330273/document https://hal.archives-ouvertes.fr/hal-00330273/file/bgd-4-3639-2007.pdf https://doi.org/10.5194/bg-5-141-2008 |
Summary: | International audience We compiled a large data-set from 22 cruises spanning from 1991 to 2003, of the partial pressure of CO 2 (pCO 2 ) in surface waters over the continental shelf (CS) and adjacent open ocean (43° to 46° S; 145° to 150° E), south of Tasmania. Sea surface temperature (SST) anomalies (as intense as 2°C) are apparent in the subtropical zone (STZ) and subAntarctic zone (SAZ). These SST anomalies also occur on the CS, and seem to be related to large-scale coupled atmosphere-ocean oscillations. Anomalies of pCO 2 normalized to a constant temperature are negatively related to SST anomalies. A depressed winter-time vertical input of dissolved inorganic carbon (DIC) during phases of positive SST anomalies, related to a poleward shift of westerly winds, and a concomitant local decrease in wind stress are the likely cause of the negative relationship between pCO 2 and SST anomalies. The observed trend is an increase of the sink for atmospheric CO 2 associated with positive SST anomalies, although strongly modulated by inter-annual variability of wind speed. Assuming that phases of positive SST anomalies are indicative of the future evolution of regional ocean biogeochemistry under global warming, we show using a purely observational based approach that some provinces of the Southern Ocean could provide a potential negative feedback on increasing atmospheric CO 2 . |
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