Abstract Submission: Large scale circulation patterns affect both the magnitude and timing of extremes. The El Niño Southern Oscillation (ENSO), the most notable climate teleconnection, is known to periodically influence precipitation regimes and flood risks. In this study, we investigate the influence of ENSO on the characteristics, namely magnitude and timing, of peak flows in the Lower Mississippi River Basin (LMRB). Records from twenty-four selected gages, two on the inlets from the Mississippi and Ohio Rivers before they discharge into LMRB, and twenty-two from the main sub-basins of LMRB, were examined. Daily mean discharges were segregated into El Niño, La Niña, and neutral water years, based on the corresponding phase of ENSO. We found that although peak flows, and even extreme peaks, may occur in any of the three periods, there is a discernible influence of ENSO on the nature of the extremes. This influence, however, is not consistent and varies geographically. A larger frequency of extreme events may be expected during El Niño on the Mississippi River, whereas on the Ohio River, higher magnitude extremes were recorded during neutral years. Downstream, in LMRB, when flow from the Mississippi and Ohio Rivers are combined, large magnitude events can be expected during both La Niña and neutral water years. In the sub-basins closer to the coast there was no discernible influence of ENSO on peak flows.
Learning Objectives/Expected Outcome (Optional) : ENSO, Extreme Flow, Mississippi River
