El Niño signals contained in precipitation at the East China Sea

ABSTRACT: In general, El Niño signals can be easily identified in the tropical Pacific Ocean but not in the East China Sea, due to the complexity of the monsoon system and insufficient knowledge of El Niño effects in mid-latitudinal regions. In this study interannual variability of precipitation at the East China Sea is analyzed. Regional correlation and the spatial distribution of interannual variation of precipitation are also analyzed in order to confirm the teleconnection pattern. Most of the rainfall stations located in the southern area of Korea show significant biennial and interannual cycles with 2 to 8 yr periodicity. As for the wavelet analysis, it was found that the periods of significant maximum power spectrum corresponded with historical El Niño episodes, especially when a strong El Niño/La Niña was repeated. Maximum positive correlation appears between the Niño3 region (equatorial eastern Pacific) and the East China Sea at a time lag of about 4 mo. This correlation tendency can be confirmed in the second mode of Empirical Orthogonal Function analysis explaining the strong El Niño event. These results also suggest variation in upper wind fields such as the Hadley circulation and East Asia jet stream.