North Pacific To The Thermohaline Conveyor

The North Pacific Ocean meridional heat and salt transport play an importantrole in the mass, heat and salt transport of the world ocean. Therefore, it is importantsignificant in both theory and practice to study the spatial and temporal characteristicsand variability of the North Pacific Ocean meridional heat and salt transport forunderstanding the role of the North Pacific in the global climate change.In this work, based on monthly mean SODA (Simple Ocean Data Assimilation)data of 50 years (1958~2007), the major feature and seasonal and interannualvariability of the North Pacific meridional heat and salt transport are extensivelyanalyzed, and the possible causes of seasonal and interannual variability in the heatand salt transport are also discussed. The major results are as follows.1.The North Pacific net meridional heat and salt transport display strong regionalcharacteristics. Namely, there is southward heat transport between 6.5°N and 10.6°N,and southward salt transport between 6.3°N and 12.2°N, with the maximumsouthward heat and salt transport at 8°N, whereas the northward heat and salttransport are seen in the north of 12.25°N, with the maximum northward heat and salttransport at 24°N. The meridional net heat and salt transport also display strongregional characteristics in seasonal change. Their seasonal changes are stronger in thesouth of 14°N than in the north of 14°N.2.The seasonal variabilities of the North Pacific net meridional heat and salttransport are mainly caused by the seasonal changes of Ekman heat and salt transportand the western, central and eastern Pacific meridional heat and salt transport on thesame latitude. Among these, the Ekman and the central-eastern Pacific meridional heatand salt transport have larger contributions, whereas the western boundary flow hassmaller contibution.3.The North Pacific net meridional heat and salt transport also display distinctregional characteristics in interannual and interdecadal variability. Namely, the netmeridional heat and salt transport have strong interannual and interdecadal variabilityon 8°N section, and experience a climate jump in 1976, while the interannual andinterdecadal variabilities of heat and salt transport in the north (14°-32°N section) areweaker.4.The interannual variabilities of the North Pacific net meridional heat and salttransport are mainly caused by the interannual variations of the western, chentral and easttern Pacific meridional heat and salt transport on the same latitude. However, theseimpacts also display regionalism. All of, the interannual variabilities in the NorthPacific net meridional heat and salt transport on 8刟N section are primarily caused bythose of the west and eastern Pacific heat and salt transport, and the interannualvariabilities in the net meridional heat and salt transport on 18刟N section primarily bythose in the eastern and western Pacific heat and salt transport, whereas theinterannual variability in the net meridional heat and salt transport on 32°N sectionprimarily by those of the central and eastern Pacific heat and salt transport.5.On interannual scale, the Ekman heat and salt transport have different impacton the North Pacific net meridional heat and salt transport in different sea region. Inother words, the Ekman heat and salt transport have larger contribution to themeridional heat and salt transport on 8刟N section, while they have smaller contributionto the meridional heat and salt transport on 18刟N section, but they play an oppositerole in the interannual variability of meridional heat and salt transport on 32刟N section.