Teleconnections of the ENSO and South Korean precipitation patterns

Abstract

Summary The climatic relationship of the ENSO phenomena (El Nino/La Nina) and monthly precipitation patterns over South Korea is examined based on the composite and harmonic analysis. Three core regions, namely the Upper Region (UR), the Middle Region (MR), and the Lower Region (LR), were identified with a high level of the spatial coherence and temporal consistency rate, which represent the geographical extent and magnitude of the response of the ENSO forcing to the precipitation patterns. During the El Nino events, the February (+) to May (+), November (0) to April (+), and November (0) to May (+) wet period for UR, MR, and LR respectively, are the signal seasons having a high level of coherence and consistency. The spatial coherence rates of each region are 0.94, 0.98, and 0.98, and the temporal consistency rates are 0.80, 0.90, and 0.80 respectively. On the other hand, in case of the La Nina events, the October (0) to January (+), November (0) to May (+) dry period for UR and MR respectively, are the signal seasons showing a strong and consistent teleconnection. The spatial coherence rates of each region are 0.98, 0.96 and the temporal consistency rates are both 0.78. According to the comparative analyses for both extreme episodes, in three core regions, the El Nino/La Nina–precipitation relationships show the opposite sign, positive and negative precipitation anomalies respectively. Based on the results of annual cycle analysis, Mann–Whitney U hypothesis test and cross-correlation analysis, the wet anomalies during the warm event years, which prevail over the whole region, are more remarkable and significant than the dry departures during the cold event years. In conclusion, the climatic teleconnection between the extreme phase of SO and mid-latitude precipitation is identified over South Korea.