Biophysical drivers of carbon uptake in western boundary current regions

Objectives

Western boundary current (WBC) regions display the largest magnitude air-to-sea carbon dioxide (CO₂) fluxes of anywhere in the global ocean, exhibit large spring blooms and high eddy activity, and are hubs for the subduction of anthropogenic carbon-laden waters into the ocean interior during mode water formation. Yet the influence of biophysical interactions on air-sea CO₂ exchange and carbon export has not been rigorously evaluated in most WBC regions.

The term Ocean Carbon Hot Spots refers to the WBC regions of the ocean, which exhibit large mean annual air-to-sea CO₂ fluxes (blue regions in Figure 1a) and elevated surface eddy kinetic energy (blue regions in Figure 1b) – characteristics ideal for the study of biophysical interactions and carbon cycle processes. 

Figure 1. (a) Climatological mean annual sea-air CO₂ flux referenced to the year 2000 adapted from Takahashi et al., 2009. Blue (red) areas are ocean sink (source) regions for atmospheric CO₂. (b) Surface eddy kinetic energy calculated from the AVISO sea surface height product. The white circle in a and b indicates the location of the Kuroshio Extension Observatory mooring. WBC systems are labeled as follows: Kuroshio Extension (KE), Gulf Stream (GS), Agulhas Return Current (ARC), East Australian Current (EAC), and Brazil-Malvinas Confluence (BMC).