Document Details

The Altamaha River estuary off the southeastern U.S. is an important source of dissolved organic carbon (DOC) to the coastal ocean. The estuary is formed by three interconnected sounds, and it is characterized by a complex network of narrow channels and creeks with high spatial heterogeneity, making it difficult to study with in situ observations alone. Here, use used satellite data from Landsat available in high resolution (30 m) to investigate DOC distribution and variability in the system. Our analyses show that DOC variability in the estuary is characterized by two seasonal peaks, one in spring and one in fall, while over the shelf maximum DOC content is observed during summer. A multiple regression analysis was used to quantify physical mechanisms controlling DOC variability in the estuary. In addition to seasonal variations, anomalies in river discharge are the dominant factor controlling DOC variability throughout much of the estuarine system. Tides play a key role near the mouth of each sound and in some upstream regions, likely associated with inputs from salt marshes. The influence of winds is smaller and is restricted to the area near the mouth of the Altamaha Sound. Landsat data also captured an input of ~ 2 Gg of DOC to the estuary associated with the passage of Hurricane Irma in 2017. Our results demonstrate that Landsat can provide useful information about scales of variability in narrow estuaries, including capturing the occurrence of sharp fronts that would be difficult to observe with traditional in situ measurements alone.

Castelao, R. and Medeiros, P.M. 2025. Satellite-derived dissolved organic carbon distribution and variability in an interconnected estuary off the southeastern U.S. Estuaries and Coasts. 48:12. (DOI: 10.1007/s12237-024-01455-3)