Horizontal and vertical distributions of colored dissolved organic matter during the Southern Ocean Gas Exchange Experiment

Field and remote sensing measurements of colored dissolved organic matter (CDOM) were acquired in the Southern Ocean during the 2008 Gas Exchange experiment. Values of CDOM absorption coefficient at 440 nm (ag440) ranged from ∼0.02 to ∼0.06 m−1. In general, CDOM was higher in the region sampled during this study than in other regions of the Southern Ocean. CDOM showed an inverse correlation with salinity, and the spectral slope parameter S varied directly with salinity. These relationships, water circulation patterns, and characteristics of South Georgia Island suggested that runoff was a source of CDOM in the study site. Analysis of seasonal variability of ag440 using ocean color imagery of areas away from the effect of South Georgia Island showed seasonal fluctuations between ∼0.02 to ∼0.03 m−1. CDOM production models showed that in situ production could also account for seasonal changes in CDOM. Key Points CDOM is higher in the GasEx Region than in areas away from South Georgia Island High CDOM can be produced in situ South Georgia Island can be a source of CDOM