북서태평양의 열대 저기압 발생 빈도와 열대 태평양 표층 수온의 상관성

Abstract

In this study we examine the relationship between the number of tropical cyclones (TCs) in the western North Pacific and the tropical Pacific sea surface temperature (SST) during the main TC season (July-August-September-October-November) for the period of 1965-2006. Results show that there are periods when TC frequency and the tropical Pacific SST are well correlated and periods when the relationship breaks down. Therefore, decadal variation is readily apparent in the relationship between the TC frequency and the SST variations in the tropical Pacific. We further examine the oceanic and atmospheric states in the two periods (i.e., 1979-1989 versus 1990-2000) when marked contrast in the correlation between the TC frequency and the tropical Pacific SST is observed. The analysis indicates that before 1990 oceanic conditions largely influenced anomalous TC frequency, whereas atmospheric conditions had little impact. After 1990, there the reverse appears to be the case, i.e., atmospheric conditions drive anomalous TC frequency and oceanic conditions are relatively unimportant. A role of atmosphere and ocean in relation to the TC development in the western North Pacific changes, which is consistent with change of the correlations between the TC frequency and the tropical Pacific SST.