Decadal-scale variability of upper ocean heat content in the tropical Pacific

[1] Decadal-scale variability of upper ocean heat content (OHC) in the tropical Pacific is investigated and is compared with that of ENSO scale. The decadal-scale OHC anomaly with a period of about 13 years shows anticlockwise propagations in the tropical North Pacific like as that of ENSO scale. It is also shown that the entire equatorial OHC anomaly leads Nino-3 index anomaly by about a quarter (about 3 years) of the period of the decadal variability in the tropical Pacific. This time lag of a quarter of the period is consistent with the idea of the "recharge oscillator'' model for ENSO dynamics. Further it is shown that the magnitude of leading OHC anomalies in the entire equatorial Pacific is linearly related to the subsequent magnitudes of Nino-3 and Nino-3.4 indices. This relationship is also similar with that of ENSO scale, but there are several different points between them. Particularly, in contrast with the ENSO scale, the amplitude is larger in central equatorial Pacific (Nino-3.4 region) than in the eastern region (Nino-3 region).