Preliminary Study Of The Pacific Sea Surface Temperature Interdecadal Variations Of Structure And Communication Mechanism

The main form of Pacific ocean temperature decadal variation and its probable origination investigated using Maryland Ocean Data Assimilation Analysis Datasets. The result show:(1) there is significant variation in the upper level of Pacific ocean, its distribution varies in different levels, but the remarkable levels all locate in the levels of the most variation with depths, which indicates that the vertical structure of Pacific decadal variation has the relationship with the stratificatrion of temperature. In thermocline, cold water is on top and warm water is at below, convection is stable, turbulence and mixture are not the same strong as in mixture level, so its thermal status is more stable. Actually thermocline performs the character that traps the signal propagating to deeper levels, which absorbes and reserves most signals, so the position of significant temperature decadal variation accords with the level of the most variation with depths.(2) The decadal signal from the surface of central north Pacific region extend to lower levels and subduct towards western south, the one from tropical western south Pacific get across equator and push forward to eastern north, the direction of propagation is along the position of most variation of temperature with depth, its main cycle is about 30 yrs. The direct character is that the water mass with greater density subducts below the one with little density, the distribution of density relates with temperature, salinity and pressure, the pressure term is little in upper levels and salinity term is quite less than temperature term. In fact, the distribution of isothermal surface represents the distribution of isopycnal surface in upper levels. So the subducting process lies on the structure of thermocline.(3) The decadal signal of north Pacific originals from ocean-atmosphere coupling, propagates from surface to deeper levels, and bring the lag of deeper levels. During the ocean-atmosphere coupling, the change of surface wind perform the key action. By changing the surface latent heat flux, the decadal change of surface wind greatly affects the surface temperature, which aroses the Pacific decadal variation. This is the direct affection of atmosphere circulation to Pacific ocean.(4) In decadal scale, wind force anomaly changes ocean current by Ekman connection, and current's change affects ocean temperature, bring its decadal change.The distribution of both current and temperature are correspondent, the decadal change of ocean temperature changes of warm currents and cold currents, and affects the vertical motion by three-dimension circulation, makes the greatly changes of ocean temperature. So the affection of ocean current to ocean temperature is not neglectable. The change of cold currents or warm currents and vertical motion is the main form of ocean current's affection to ocean temperature, and it's the indirect affection of atmosphere circulation to ocean temperature.Our article analyse the reason of Pacific ocean temperature decadal variability, but they only focus on diagnoses, the origin lies on ocean numerical models.