Thermal variability of the Indo-Pacific warm pool

Abstract

The Indo-Pacific warm pool (IPWP) over the Indian Ocean and the Pacific Ocean is the largest warm pool in the global oceans. Its thermal variability and trend between 1982 and 2011 are extracted from the Ensemble Empirical Mode Decomposition method. Time–frequency energy distributions using the Hilbert–Huang transform are computed to evaluate the thermal spectrum-energy. From the SST variability and the heat storage anomaly, we find that the thermal variability is strongly influenced by the Pacific Decadal Oscillation (PDO). The size, increasing trend in the IPWP, calculated from the SST data is (0.18±0.01)×106km2/decade. Besides, the magnitude of increasing rate during the positive phase of the PDO is couple times higher than that during the negative phase. Furthermore, the SST trend is also associated with 1999/2000 climate shift. The heat increases in the IPWP from 1993 to 2011 implied an average warming rate of 1.41Wm−2. The thermal variations in the IPWP are controlled by interannual to decadal variabilities mostly related to the PDO in the Pacific Ocean sector and by annual variability in the Indian Ocean sector.