The hiatus and accelerated warming decades in CMIP5 simulations

Observed hiatus or accelerated warming phenomena are compared with numerical simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5) archives, and the associated physical mechanisms are explored based on the CMIP5 models. Decadal trends in total ocean heat content (OHC) are strongly constrained by net top-of-atmosphere (TOA) radiation. During hiatus decades, most CMIP5 models exhibit a significant decrease in the SST and upper OHC and a significant increase of heat penetrating into the subsurface or deep ocean, opposite to the accelerated warming decades. The shallow meridional overturning of the Pacific subtropical cell experiences a significant strengthening (slowdown) for the hiatus (accelerated warming) decades associated with the strengthened (weakened) trade winds over the tropical Pacific. Both surface heating and ocean dynamics contribute to the decadal changes in SST over the Indian Ocean, and the Indonesian Throughflow has a close relationship with the changes of subsurface temperature in the Indian Ocean. The Atlantic Meridional Overturing Circulation (Antarctic Bottom Water) tends to weaken (strengthen) during hiatus decades, opposite to the accelerated warming decades. In short, the results highlight the important roles of air-sea interactions and ocean circulations for modulation of surface and subsurface temperature.