Assessing the meridional atmosphere and ocean energy transport is one of the most classical problems in climate research.The meridional energy transport plays a critical role in maintaining the equilibrium of the earth system.Although the principle to calculate the meridional energy transport is simple,many fundamental questions remain unsolved.For example,what are the intrinsic mechanisms to maintain the hemispherically antisymmetric structure in the total energy transport? How on earth does the meridional energy transport partition between the atmosphere and ocean and,is there really a so-called "Bjerknes compensation" relationship between them? This relationship would provide us deep insight into the coupling mechanisms between the ocean and atmosphere in global scale.In this review we try to come out some important problems that are deserved in-depth investigations in current climate studies.
The equatorial response to subtropical Pacific forcing was studied in a coupled climate model. The forcings in the western, central and eastern subtropical Pacific all caused a significant response in the equatorial thermocline, with comparable magnitudes. This work highlights the key role of air–sea coupling in the subtropical impact on the equatorial thermocline, instead of only the role of the "oceanic tunnel". The suggested mechanism is that the cyclonic(anticyclonic) circulation in the atmosphere caused by the subtropical surface warming(cooling) can generate an anomalous upwelling(downwelling) in the interior region. At the same time, an anomalous downwelling(upwelling) occurs at the equatorward flank of the forcing, which produces anomalous thermocline warming(cooling), propagating equatorward and resulting in warming(cooling) in the equatorial thermocline. This is an indirect process that is much faster than the "oceanic tunnel" mechanism in the subtropical impact on the equator.
