ENSO Influences on Seasonal Rainfall and River Discharge in Florida

Hemispherical and regional analyses of climatic patterns relating to El Niño–Southern Oscillation (ENSO) indicate strong responses in the southeastern United States, especially during the wintertime. Using Florida as an example, the authors focused on local-scale patterns within this region in order to examine the geographic variability of seasonal rainfall and river discharge as related to ENSO. Forty-eight years (1950–98) of precipitation and river discharge data in Florida were classified, using sea surface temperature anomaly data from the equatorial Pacific Ocean, as occurring during an El Niño (warm event), La Niña (cold event), or neither (neutral). Seasonal precipitation and streamflow both exhibited strong responses to ENSO as shown by their relationships to Niño-3.4 sea surface temperature anomalies. Florida does not respond as a uniform region to ENSO, particularly with respect to precipitation in the Panhandle and the southernmost areas of Florida. In particular, seasonal river discharge in south-central Florida responds in a complicated manner to ENSO conditions; however, there are seasonal ENSO patterns. The authors have linked the results of larger regional and hemispherical research to a focused local-scale approach that demonstrates variability in precipitation and river flow using datasets and statistical techniques that are readily available to and interpretable by water resource planners and managers