School of Earth and Space, University of Science and Technology of China
The authors researched the inter-decadal trend shifts of latent heat flux (LHF) over the Kuroshio extension (KE) region and Gulf Stream (GS) region during the warming period and the warming hiatus period by using the latent heat flux data and relevant variables produced by the Objectively Analyzed Air-Sea Fluxes project (OAFlux) of the Woods Hole Oceanographic Institution, and the Ishii subsurface temperature and salinity data from Japan Agency for Marine-Earth Science and Technology. Small perturbation method, EOF analyzation, and International Thermodynamic Equation Of Seawater – 2010 (TEOS?10) are applied in this research. Contrast inter-decadal trend shifts of latent heat flux exist in KE and GS region. The inter-decadal LHF trend of KE region shifts from positive to negative around 2001, while the GS region shifts from negative to positive around 1993. The variation of KE region is primarily resulted from sea surface temperature change (ocean-induced) , while in GS region it is resulted from wind speed (1979~1992) (atmosphere-induced) and sea surface temperature (1993~2013).The inter-decadal variations of seawater heat content in KE and GS regions are also different: the inter-decadal variation of surface heat content in KE region is consistent with mixed layer; the inter-decadal variation of surface heat content in GS region is different from that in deep layer, while the changes below surface layer are more consistent; the deep heat content changes in both regions reflect the phenomenon of warming hiatus, and KE region may have the influence of the lower layer to the upper layer; while GS region may have the influence of the upper layer to the lower layer. The difference between the surface of KE and GS can be attributed to the difference between ocean and atmospheric factors, and the vertical difference of inter-decadal variation of internal heat content may be attributed to the structural difference between the two regions. All of those variations are associate with the warming hiatus, and may affect the warming hiatus conversely.