Regional sea surface temperature (SST) mode variabilities, especially the La Niña-like Pacific Ocean temperature pattern known as the negative phase of the Interdecadal Pacific Oscillation (IPO), and the associated heat redistribution within the ocean are the leading mechanisms explaining the recent global warming hiatus. Here we use the Community Earth System Model (CESM) version 1, to examine how different phases of two leading decadal timescale SST modes, namely the IPO and the Atlantic Multidecadal Oscillation (AMO), contribute to heat redistribution in the global ocean in the absence of time evolving external forcings.
Our results show that both the IPO and AMO contribute a similar magnitude to global mean surface temperature and ocean heat redistribution. Both modes contribute warmer surface temperature and higher upper ocean heat content in their positive phase, and the reverse in their negative phase. Regionally, patterns of ocean heat distribution in the upper few hundred meters of the tropical and subtropical Pacific Ocean depend highly on the IPO phase via the IPO associated changes in the subtropical cell. In the Atlantic, ocean heat content is primarily associated with the state of the AMO. The differences between IPO and AMO’s influence on ocean heat content is that IPO can induces an opposite sign of ocean heat content change between surface and subsurface layers of the ocean, but AMO induces a heat content change in the same sign up to 1500m depth
- Our results show that both IPO and AMO can modulate the ocean heat content distribution.
- The major influence of IPO is in the Pacific basin, and the major influence of AMO is in the Atlantic with significant impact to other basins in association to AMOC.
- IPO can induce a seesaw-like heat content change between the surface and subsurface oceans.
- AMO will, in general, induce heat content change with the same sign up to 1500m depth.