Teleconnection of ENSO extreme events and precipitation variability over the United States

•The linkage between the El Niño/La Niña and precipitation over the contiguous United States is examined.•Five core regions were detected based on composite and harmonic analysis, etc.•The El Niño/La Niña-precipitation relationships show the opposite sign, positive and negative.•The teleconnection between the ENSO and mid-latitude precipitation is identified over the contiguous United States. This study describes a comprehensive investigation of the contiguous United States precipitation patterns in relation to the warm and cold phases of El Niño/southern Oscillation (ENSO) using a set of empirical and statistical analyses, such as harmonic analysis, annual cycle composites, and cross-correlation analysis. Monthly precipitation composites for the first harmonic, covering 24-month ENSO events, are formed for all climate divisions over the United States spanning up to 29 ENSO episodes. From the harmonic vectorial maps plotted on the study area, each vector reveals both intensity and temporal phase of the ENSO-related precipitation teleconnection, and the corresponding candidate and core regions are determined using a machine learning technique of Gaussian Mixture Model (GMM) based on magnitude and temporal phase of climate signal, and Köppen climate classification. As a result of vectorial mapping, five core regions were designated as North-West region (NW), South-West region (SW), Middle-Inland region (MI), South-East region (SE), and North-East region (NE). During fall (0) to spring (+) seasons, the results of this analysis show below (above) normal precipitation response to the El Niño events at the NW region (SW, MI, SE, and NE regions), while the opposite patterns are detected for the cold phase of ENSO. The temporal consistency values were 0.72 to 0.86 (0.77 to 0.82), and spatial coherence values ranged from 0.96 to 0.99 (0.94 to 0.99) for the warm (cold) events. Comparative analyses of precipitation responses to both El Niño and La Niña events reveal the high significance level of the ENSO-related precipitation signals with an opposite tendency in monthly precipitation anomalies. Positive precipitation anomalies during the El Niño thermal forcing are more significant than negative precipitation departures during the La Niña events. Consequently, middle latitude precipitation responses to the El Niño/La Niña phenomena are detectable over the contiguous United States.