Impacts of Different Types of El Nino on the East Asian Climate: Focus on ENSO Cycles

Using multiple datasets and a partial correlation method, the authors analyze the different impacts of eastern Pacific (EP) and central Pacific (CP) El Nino on East Asian climate, focusing on the features from El Nino developing summer to El Nino decaying summer. Unlike the positive-negative-positive (+/-/+) anomalous precipitation pattern over East Asia and the equatorial Pacific during EP El Nino, an anomalous -/+/- rainfall pattern appears during CP El Nino. The anomalous dry conditions over southeastern China and the northwestern Pacific during CP El Nino seem to result from the anomalous low-level anticyclone over southern China and the South China Sea, which is located more westward than the Philippine Sea anticyclone during EP El Nino. The continuous anomalous sinking motion over southeastern China, as part of the anomalous Walker circulation associated with CP El Nino, also contributes to these dry conditions. During the developing summer, the impact of CF El Nino on East Asian climate is more significant than the influence of EP El Nino. During the decaying summer, however, EP El Nino exerts a stronger influence on East Asia, probably due to the long-lasting anomalous warming over the tropical Indian Ocean accompanying EP El Nino. Temperatures over portions of East Asia and the northwestern Pacific tend to be above normal during EP El Nino but below normal from the developing autumn to the next spring during CP El Nino. A possible reason is the weakened (enhanced) East Asian winter monsoon related to EP (CP) El Nino.