Assessing COS Spatiotemporal Variability in the Surface Waters of Two Key Regions

durch Li Zhou

Mittwoch 23.07.2025, 13:15 → 14:30 Europe/Berlin

8A-002 - Hörsaal Ostufer / Lecture Hall East (GEOMAR - Standort Ostufer / GEOMAR - East Shore)

Abstract

Carbonyl sulfide (COS) is an abundant atmospheric trace gas with important climate implications. Marine emissions of COS dominate the atmospheric sources, but large uncertainties remain in specific key regions. Here, we present a dataset of COS surface concentrations and atmospheric mixing ratios from three cruises spanning 30°N to 80°S. These data cover all seasons and two key regions: the western Pacific, hypothesized to be a missing source region, and the Southern Ocean, hypothesized to be the area with highest seawater concentrations and emissions. We confirm that the northwestern Pacific, which has been suggested to be a hot spot for marine emissions in atmospheric top-down modelling, could not explain the missing atmospheric sources and may be more influenced by local land emissions than ocean emissions. With respect to the Southern Ocean, we present the first mechanistic assessement of COS cycling. Analysis of temporal trends in the Southern Ocean showed that COS surface seawater concentrations are highest in summer, consistent with modeled distributions, but the average value in this region is 22% lower than modeled. Modeled COS fluxes are generally higher than observed (more than 100%), with distinct latitudinal difference.