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Freshwater delivery is an important factor determining salinity in the LTER Georgia Coastal Ecosystem (GCE) site. Variability in freshwater delivery was examined in relation to various climate indices: the Southern Oscillation Index (SOI), the North Atlantic Oscillation (NAO) and the Bermuda High Index (BHI). Monthly standardized anomalies of river discharge and climate indices were compared with multi-decadal time series of Altamaha watershed precipitation at 7-13 stations using empirical orthogonal function (EOF) analysis to describe the precipitation patterns. The first EOF mode (65% of the variance) was spatially uniform with temporal variability at the monthly scale. The second mode (11% of the variance) showed a spatial gradient along the long axis of the watershed (NW-SE) whereas the third mode (6% of the variance) showed an onshore-offshore pattern with higher variability during June-September. There were no consistent relationships between NAO and precipitation. The SOI shows correlations with discharge and weak correlations with modes 1 and 2 of the precipitation. The BHI is correlated with May-January discharge with a 0-1 month lag, and is also strongly correlated with EOF mode 1 of precipitation. The occurrence of tropical storms in theregion is also strongly related to the BHI, but not the SOI.

Sheldon, J.E. and Burd, A.B. 2009. Poster: The Effects of Climate Signals on Freshwater Delivery to Coastal Georgia, U.S.A. 2009 LTER All Scientists Meeting, Sept. 14-16, 2009, Estes Park, CO.