Patterns of coherent decadal and interdecadal climate signals in the Pacific Basin during the 20th century

Two distinct low-frequency fluctuations are suggested from a joint frequency domain analysis of the Pacific Ocean (30S-60 degreesN) sea surface temperature (SST) and sea level pressure (SLP). The lowest frequency signal reveals a spatially coherent interdecadal evolution. In-phase SST and SLP anomalies are found along the subarctic frontal zone (SAFZ). It is symmetric about the equator. with tropical SST anomalies peaking near 15 degrees latitudes in the eastern Pacific. The other low-frequency signal reveals a spatially coherent decadal evolution. It is primarily a low-latitude phenomenon. Tropical SST anomalies peak in the central equatorial ocean with evidence of atmospheric teleconnections. These interdecadal and decadal signals join the ENSO and quasibiennial signals in determining dominant patterns of Pacific Ocean natural climate variability. Relative phasing and location of the SST and SLP anomalies for the decadal. ENSO, and the quasi-biennial signals, are similar to one another but significantly different from that of the interdecadal signal.