The Meridional Overturning Circulation (MOC) plays a major role in the carbon cycle by meridional redistribution of carbon and nutrients. In the North Atlantic, biological productivity and associated carbon uptake by the Biological Carbon Pump (BCP) is supported by northward nutrient transport in the upper limb of the MOC. Changes in MOC strength might thus be expected to alter regional nutrient cycles and the strength and/or efficiency of the BCP. Observations from the RAPID, Argo and GO-SHIP International Programs were used to obtain a continuous time series of the basin-wide meridional nutrient transport across the 26.5°N-RAPID section for the 2004–2012 period, and to calculate in situ cruise-based nutrient transports and inventories in 2004 and 2010 (A05-24.5°N and OVIDE sections). In this talk I will show the results from the analysis of these data, demonstrating that the overturning circulation strength dominates the total nutrient transports on all time scales (MOC explaining ~90% of the variance), and ultimately providing multiple lines of evidence for non-steady state behavior and increasing efficiency of the BCP in the North Atlantic corresponding to the observed MOC slowdown.
Wednesday 5 June 2019 - 11:00 to 12:00
NOC Southampton - Node Room (074/02) (Waterfront Campus).
Lidia Carracedo (NOC)