Impact of Two Distinct Teleconnection Patterns Induced by Western Central Pacific SST Anomalies on Korean Temperature Variability during the Early Boreal Summer

Abstract

This study investigates the impact of western central Pacific sea surface temperatures (SSTs) on the temperature variability over the Korea Peninsula during the early boreal summer season. The authors found a significant positive correlation between June temperature anomalies across the Korea Peninsula and a horseshoe pattern of ENSO-related SST anomalies in the western central Pacific during May. While this SST pattern is relatively stationary throughout the boreal summer, the SST-driven atmospheric teleconnection exhibits dramatic subseasonal changes. During May, positive precipitation anomalies caused by SST warming in the northern central Pacific (NCP; 20 degrees-30 degrees N, 160 degrees E-160 degrees W) induce a wave train extending in a northwest-southeast direction. During June, while this wave train pattern is weakened, a Pacific-Japan (PJ) pattern is formed by positive precipitation anomalies over the off-equatorial western Pacific (off-WP). Even though dramatic subseasonal changes exist in the teleconnection patterns, both patterns contribute to temperature warming over Korea. It is shown that the subseasonal change in the atmospheric teleconnection is caused by changes in climatological precipitation. During May, significant climatological precipitation related to the pre-mei-yu and pre-baiu fronts occurs over the NCP. These wet background conditions provide a favorable environment for anomalous convection over the NCP but not over the off-equatorial western Pacific. On the other hand, during June, convective activities over the off-WP result in the formation of a PJ pattern, enhanced by an increase in climatological precipitation associated with the activation of the western North Pacific (WNP) monsoon. These results indicate that climatological conditions play an important role in the formation of atmospheric teleconnection linking Pacific and East Asian climates.