Freshwater variability and predictability in the Alaska Coastal Current

November-May anomalies of ACC mass transport, FWT, and FWC are significantly correlated with runoff anomalies and the latter are significantly correlated with anomalies of Ketchikan-Seward atmospheric sea level pressure gradient. These results lead to a 20th century runoff record that permits retrospective examination of the ACC. It appears that the wettest (driest) decade was the 1920s (1900s) during which time ACC transports decreased (increased). While the Pacific Decadal Oscillation is correlated with this “runoff” time series, it explains <25% of the runoff variance. Coastal measurements of salinity and/or dynamic height are better predictors of these ACC variables than runoff, suggesting that along-shelf monitoring of the ACC might be achieved using simple measurements at only a few coastal stations.