Multi-scale variation of the meridional movement of the western Pacific warm pool and its associated large-scale climate features

Abstract

In this study, we investigated variation of the meridional movement of the western Pacific warm pool (WPWP). The variation was measured by the central latitude (Clat) of the WPWP on various time scales. Its relationships with global sea surface temperature (SST), precipitation, and atmospheric circulation were examined by applying several advanced statistical methods. First, the techniques of wavelet analysis and least-square adjustment were used to depict the time-frequency features and the mean dominant oscillating time scales of the Clat. Then, a multi-stage filtering technique was applied to illustrate the related dominant oscillating signals. We also examined the time-frequency characteristics of the relationships between Clat and the leading modes of the Indo-Pacific oceans by employing a cross-covariance function analysis and a multiple moving-window method. The physical mechanisms for the relationships between Clat and the patterns of SST, precipitation, and atmospheric circulation were discussed. Results indicated that there is a weakening trend in the oscillation of Clat mainly because the quasi-annual oscillation of Clat increases in January-March and decreases in July-September. The semi-annual oscillation of Clat closely interacts with the westerly wind over the summer hemisphere of the tropical western Pacific Ocean and with the easterly wind over the winter hemisphere of the ocean. The interannual component of Clat corresponds to El Niño-Southern Oscillation and the Indian Ocean basin-wide warming or cooling with strengthened oscillations in the 1970s, and the lower-frequency component of Clat closely corresponds to the central Pacific type of El Niño from the 1990s.

Seasonal and Interannual Variability of the Indo-Pacific Warm Pool and its Associated Climate Factors Based on Remote Sensing

“…In addition, the zonal variation was found leading the Niño 3 index 3-4 months and the depth variation was found lagging the index for three months. The time-frequency features of the central latitude of the WPWP have also been investigated on multi-time scales from 1948 to 2012 in detail [23]. Moreover, Kim et al [4] firstly introduced five warm pool surface properties to delineate the variabilities of the warm pool and contrasted the similarities and differences of the Indian Ocean sector and the Pacific Ocean sector on the seasonal and interannual time scale.…”

Spatio-Temporal Characteristics of the Indo-Pacific Warm Pool and the Corresponding Rain Pool

“…The essential basis for the interaction between ocean and atmosphere is sea surface temperature (SST). When the SST rises beyond a certain threshold, structured deep convective systems transfer heat and moisture from the ocean to the atmosphere, serving as a significant source of heat and water vapor for large-scale atmospheric circulations [2][3][4]. In the tropical ocean-atmosphere system, where there is high SST, there is usually more precipitation because of the moist deep convective systems that quickly grow over it [5].…”