Interactions between the Atlantic Multidecadal Oscillation, El Niño/La Niña, and the PNA in winter Mississippi Valley stream flow

Abstract

Winter streamgage data at 554 locations in the U.S. Geological Survey's Hydro‐Climatic Data Network are used to evaluate interactions between the Atlantic multidecadal oscillation (AMO), the Pacific/North American (PNA) teleconnection pattern, and warm and cold equatorial Pacific Niño 3.4 events in producing Mississippi River basin discharge variations. The AMO is linked to statistically significant stream flow differences over the upper Mississippi Valley, as well as low (high) winter stream flow from 1930–1959 (1965–1994). Its influence in the lower Mississippi Valley is however not as apparent because of 4 consecutive wet winters, 1949–1952, that disrupt the AMO warm/dry period. Persistent PNA zonal flow, and a La Niña event, occur during these winters and they are closely linked to high Tennessee and Ohio River valley stream levels. PNA‐influenced stream flow on these rivers has a greater long‐term winter impact on the lower Mississippi basin than does flow from the upper Mississippi.