The variability of surface pCO2 and nutrients in the North Atlantic Ocean

• Main Author: Lüger, Heike
• Format: Thesis
• Language: English
• Published: 2003
• Subjects: Western Basin; North Atlantic
• Online Access: https://oceanrep.geomar.de/id/eprint/59323/; https://oceanrep.geomar.de/id/eprint/59323/1/Diss_Lueger_H_2003.pdf; https://macau.uni-kiel.de/receive/diss_mods_00000987

This PhD thesis was part of the EU-funded project CAVASSOO (Carbon Variability Studies by Ships of Opportunity). The major goal of the project was to establish an international network in the North Atlantic consisting of commercial vessels that are equipped with pC02 measurement devices. The installation of a autonomously working pC02 unit onboard the carcarrier M/V Falstaff was completed in January, 2002. Measurements started a month later with the first transatlantic crossing. In the following months continuous and discrete samples were analyzed. It was examined whether it is possible to correlate the oceanic pC02 with parameters that can be retrieved by ship-independent observations such as remote sensing. The correlatin between pC02 and nitrate was promising in this context and it could also be shown that nitrate correlated well with the mixed layer depth. Parameters such as temperature and chlorophyll on the other hand did not reveal a unique correlation with the pC02. Within this thesis it was also shown that the seawater pC02 in the eastern basin (l0 °W-35 °W) showed smaller seasonal changes than in the western basin (36°W-70 °W) in the North Atlantic. This was explained by the fact that in the eastern basin the temperature effect on the seawater pC02 was counteracted by the biological effect yielding a damped easonal pC02 cycle. In the western basin, however, temperature was the major force on the pC02 which was not reduced by a counteracting biology effect thus yielding a pronounced seasonal pC02 cycle. The C02 flux calculation showed that this region of the North Atlantic was a sink for atmospheric C02 in 2002. When comparing the C02 flux to a well-cited pC02 climatology the difference was small (4%). The seasonal cycles of nutrients within different watermasses showed distinct patterns. The C:N ratio of the seasonal new production were similar to the Redfield ratio for all watermasses excecpt for the Gulfstream watermass. In the latter a carbon overconsumption with respect to Redfield could be shown ...