Tidal harmonics at the GCE monitoring sites Dr. Jackson O. Blanton Skidaway Institute of Oceanography

10 Ocean Science Circle Savannah Georgia 31411 USA

jack.blanton@skio.uga.edu http://www.skio.peachnet.edu/faculty/blanton.html Georgia Coastal Ecosystems LTER Project

Dept. of Marine Sciences University of Georgia Athens Georgia 30602-3636 USA

gcelter@uga.edu https://gce-lter.marsci.uga.edu/ Dr. Jackson O. Blanton Skidaway Institute of Oceanography

10 Ocean Science Circle Savannah Georgia 31411 USA

jack.blanton@skio.uga.edu http://www.skio.peachnet.edu/faculty/blanton.html Principal investigator Dr. Daniela Di Iorio University of Georgia

Dept. of Marine Sciences University of Georgia Athens Georgia 30602-3636 USA

daniela@uga.edu http://www.marsci.uga.edu/directory/daniela-di-iorio Co-investigator 2026

An REU student from the Georgia Tech Regional worked with Jack Blanton in 2002 to analyze the tidal harmonics observed at seven of the monitoring sites in the LTER domain. Table 1 shows the dominant harmonics for two contemporaneous time periods for the seven stations, each lasting 2 months. The form factor (K1+O1)/(M2+S2) gives the relative strength of the diurnal inequality for each station during each time period. The tidal wave becomes increasingly distorted as it travels between the ocean and the upstream portion of the two tidal channels, as indicated by an increase in the M4/M2 amplitude. However, when one compares the relative phases (2*M2-M4), the duration of ebb and flood flows are almost equal in Sapelo Sound. By contrast, the Altamaha River is dominated by stronger and longer ebb flows, consistent with the seaward pressure gradient associated with freshwater discharge.

Question 2: How do the spatial and temporal patterns of biogeochemical processes, primary production, community dynamics, decomposition, and disturbance vary across the estuarine landscape, and how do they relate to environmental gradients? (more information)

LTER NSF Georgia Sapelo Sound GCE discharge ebb flow freshwater harmonics tidal Overall geographic extent of the research project -81.431980 -81.154122 31.559628 31.516636 2002-06-01 2002-09-01

National Science Foundation grant numbers OCE-9982133 and OCE-0620959

estuary marsh complex Sapelo River - Sapelo River transect used for GCE quarterly hydrographic monitoring surveys. Nominal profiling stations are defined every 3-4km from 0km to 36km (relative to station 0km at the line of demarcation), based on an estimated Thalweg line running up the main river channel. -81.431980 -81.154122 31.559628 31.516636 Table 1. Dominant harmonics for two contemporaneous time periods for the seven stations, each lasting 2 months https://gce-lter.marsci.uga.edu/public/resources/projects/Table1HarmonicsQ2Di.png