DOES THE EL NINO SOUTHERN OSCILLATION LEAVE AN IMPRINT ON THE MISSISSIPPI RIVER'S DISCHARGE RECORD?

The El Nino Southern Oscillation is the one of the largest, and most dynamic component of Earth’s climate system. Yet, to date, few studies have shown a relationship between ENSO and flow in North America’s largest river. This study attempts to discern relationships between ENSO by examining the discharge anomaly in Mississippi River using a suite of statistical tools, climate indices, and climate reanalyses. While ENSO is not the only influence on flow anomalies in the Mississippi River, periods with strong El Nino events appear to also have high discharges. The link appears to be moisture, originating in the tropic Pacific Ocean, which is transported across North and/or Central America. The former yields enhanced precipitation in the western half of the Mississippi River watershed, and the latter yields enhanced Gulf of Mexico moisture that feeds precipitation in the eastern half of the Mississippi River watershed. These findings have the potential to influence preparations for flood fights, coastal sediment management, and hypoxia forecasts, which are dependent on Mississippi River stage, as El Nino events are predicted on time scales that are substantially longer than current river stage predictions.