CO2 flux variability in the Galician Upwelling System

• Autor(a) principal: Pacho, Laura
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.1/12586
• topic: Dióxido de carbono; Afloramento costeiro; Troca ar-mar de CO2; Aquecimento global; Domínio/Área Científica::Ciências Naturais::Outras Ciências Naturais

Coastal upwelling occurring along the eastern ocean margins (EBUS), at the four major eastern boundary current regions of the World Ocean: California, Canary, Benguela, and Peru/Humboldt, induces offshore surface Ekman Transport and promotes the rise of deep nutrient and CO2-rich water into the euphotic zone. However, how these coastal upwelling systems will behave next years due to climate change, its something that scientists do not understand yet perfectly well. Within this context, Bakun in 1973 published a theory explaining why climate change will promote an intensification of upwelling. Scientists around the world are trying to test this hypothesis despite some contradictions exist between them. The objective of this work was to approach this topic studying Galician upwelling system using data collected between 1997 and 2018 by the Marine Research Institute in Vigo, España. The database included CO2 partial pressure at sea surface (pCO2sw), sea surface temperature (SST) and sea surface salinity (SSS), Wind Speed (NCEP/NCAR) and (CCMP), Chla and NEP (SeaWiFS and MODIS). The results showed that the tendency of wind speed during Spring and Summer is to decrease from 1997 to 2018, contrary to that stated by Bakun. Although it is not possible to establish a downward trend of the upwelling index, it is true that the maximum values from 1997 to 2018 have decreased with respect to those achieved from 1997 to 2009. fCO2sw has two main components that define its behavior, which are the biological component, related to photosynthesis and heterotrophic processes, and the physical component of temperature that comes into play at times of maximum upwelling index. Within the Ria de Vigo seasonality and the effects of upwelling are much stronger than offshore. Moreover, there the contribution from the continental waters areimportant . The North Atlantic Oscillation is related to SST and to ΔfCO2, which is important at the time of looming interannual cycles, although in this work there is no high inter-annual cyclical component for fCO2sw.