A Study of the Short-term Variability of Seawater pCO₂ near Östergarnsholm

Abstract:

In this study, an analysis of upwelling and biological activities impact on the seawater pCO₂ variability was done to improve the knowledge about the pCO₂ variability in seawater in the Baltic Sea. During upwelling activity, CO₂ rich waters are upwelled to the surface. This influences air-sea CO₂ flux and thus the net uptake/emission of CO₂ by the sea. pCO₂ and SST measurements from a SAMI sensor, located at the Östergarnsholm site in the Baltic Sea, and SST satellite data, was used to identify periods affected by upwelling activity. A strong variability due to upwelling activity was observed on the pCO2 concentration. The frequency of upwelling activity at the Östergarnsholm site was estimated to be around 20 % of the time from May-November. The relationship between pCO₂ and SST during upwelling activity was found to depend of the month. In November, this relationship can be used to characterise the effect of upwelling, but for the other months there are no differences between the none- upwelling periods and the upwelling periods. Another type of period, characterized by a diurnal variability of pCO₂ mainly driven by the biological effect, was also observed.