Pacific Decadal Oscillation 변동에 관한 연구

Abstract

A long-term time series of the North Pacific mean sea surface temperature (SST) is characterized by two distinct epochs in observations, i.e., the cold epoch (1870-1935) versus the warm epoch (1945-2007). By directly comparing the Pacific Decadal Oscillation (PDO) between the two epochs we examine characteristic change in the PDO in relation to change in the mean SST in the North Pacific. While the spatial structure of the PDO is little changed from the cold epoch to the warm epoch, the temporal structure of the PDO is significantly changed between the two epochs. During the last half of the 20th (i.e., warm epoch), the period when one phase of the PDO persists becomes longer and low frequency variability in the PDO is dominant compared to the cold epoch. We argue that such change in the PDO is closely associated with changes in the PDO-ENSO relationship from the warm epoch to the cold epoch.