POSTER SESSION 2
10:30–12:30, Tuesday, September 15
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
ABSTRACT 1138 | POSTER 6
SEASONAL, TREND, AND IRREGULAR VARIABILITY OF SOUTHERN OCEAN SURFACE PCO₂: A SCALE-DEPENDENT VIEW FROM CIRCUMPOLAR TO FRONTAL ENVIRONMENTS
Understanding Southern Ocean partial pressure of CO2 in surface seawater (pCO2w) variability requires accounting for processes that act across contrasting spatial scales. Here, we analyze monthly surface pCO2 south of 45°S over the period 1999-2022 using a new reconstruction of Southern Ocean surface pCO2 based on SOCATv2024 in situ observations, ocean color satellite data, reanalysis products, and Census X-13 time-series decomposition. At the circumpolar scale, our results indicate that variability is primarily seasonal, explaining approximately 90% of the total variance. The trend component accounts for a much smaller fraction of the variance (approximately 6%) and shows a coherent, although weak, relationship with the Southern Annular Mode (SAM), suggesting a detectable link to climate variability without dominating total variability. In contrast, local-scale decomposition reveals a broad circumpolar band in which pCO2 variability is frequently dominated by the irregular component. This irregular-dominant region partially overlaps the Antarctic Circumpolar Current frontal system, but extends beyond the frontal core, indicating enhanced variability across the broader frontal environment. This feature is strongly masked by spatial averaging, showing that circumpolar means damp an important fraction of local variability. Climatological analyses further show that Southern Ocean pCO2 is spatially heterogeneous and that its seasonal cycle cannot be interpreted as a purely thermodynamic response to temperature, particularly at high latitudes where non-thermal controls dominate. These results highlight a scale-dependent organization of Southern Ocean surface pCO2, with seasonal variability dominating at circumpolar scale and irregular variability becoming prominent within a broad frontal belt.
Maximiliano Arena, Laboratoire d’Océanologie et de Géosciences (LOG), [email protected], https://orcid.org/0000-0001-6162-9716
Hubert Loisel, Laboratoire d’Océanologie et de Géosciences, [email protected]
Roy El Hourany, Laboratoire d’Océanologie et de Géosciences, [email protected]
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
