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Keywords:

  • Western Pacific teleconnection pattern;
  • rainfall;
  • sea surface temperature

Abstract

This study analyses the correlation between western Pacific (WP) teleconnection pattern index (WPI) in April and rainfall amounts in the same month during 1954–2008. On the basis of the results, it is identified that there have been strong positive correlations between central China, Korea, and the southwestern part of Japan in the East Asian region. Through differences between 10 positive WP years and 10 negative WP years selected from the April WPI excluding El Niño-Southern Oscillation years, it is found that rainfall amounts increase in April of positive WP years due to the following characteristics. Increases in rainfall amounts are evident in the East Asian middle latitudinal region where the positive correlation between the two variables is the highest and this is because anomalous southwesterlies are strengthened in the East Asian middle latitudinal region due to the spatial pattern of a south-low-north-high anomalous pressure system centered on this region that is made by anomalous anticyclones centered on the southeastern side of the region and other anomalous anticyclones centered on the northeastern side of the region. In addition, anomalous westerlies (jet) are strengthened in the upper troposphere of the East Asian middle latitudinal region. As a result, anomalous upward flows are strengthened in this region and thus anomalous warm air temperatures are formed in the entire level of the troposphere in the region. In addition to atmospheric environments, anomalous warm sea surface temperatures are formed in the seas in the East Asian middle latitudinal region to help the rainfall amount increases in the East Asian middle latitudinal region. Copyright © 2012 Royal Meteorological Society