CO2 Sink and Source Zones Delimited by Marine Fronts in the Drake Passage

ARBILLA, LA; RUIZ-ETCHEVERRY, LA; LÓPEZ-ABBATE, MC; KAHL, LC; BIANCHI, AA

Simposio; 5th International Symposium on the Ocean in a High CO2 World; 2022

Universidad Pedro Ruiz Gallo National

The Southern Ocean, on average, is the largest sink of anthropogenic CO2 of the global ocean. However, recent studies show that carbon fluxes are highly dynamic over time and they respond to the interaction of different scale processes. Therefore, the objective of this work is to study the factors that modulate CO2 fluxes (FCO2) in the Drake Passage (DP), a transition area between the South Atlantic and South Pacific oceans.Using the SOCAT (Surface Ocean CO2 Atlas) database, circumpolar fronts, and physical and biological variables were used to analyze the spatial patterns of the sea/atmosphere gradient of the partial CO2 pressure (ΔpCO2) and FCO2 at a climatological scale (1999-2019). In other regions of the world the fronts play a fundamental role in the distribution of carbon sources and sinks. Consequently, the monthly climatological position of the most important fronts of the DP, the Subantarctic Front (SAF), the Polar Front (PF) and the Southern Antarctic Circumpolar Current Front (SACCF), was estimated using satellite altimetry data. The results show a coherence between the FCO2 spatial distribution and the physical front positions. The region to the north of SAF behaves as a sink (ΔpCO2 < 0 μatm); this sink weakens between SAF and SACCF and the region to the south of SACCF acts as a CO2 source. We also analyzed the relationship between FCO2 with thermal (TE) or non-thermal (NTE) effects. The relative importance of these processes shows that to the north of SACCF the TE dominates the CO2 variability, whereas in the region south of SACCF the NTE dominates. This research shows that the CO2 dynamic in the DP is not dominated by a single process, but rather responds to both thermal and non-thermal processes. Finally, the interannual variability is analyzed.