Preliminary Study On The Interdecadal Variability Of The North Pacific Climate And A Simple Mechanism Of Coupled Ocean-Atmosphere Interaction

The upper layer heat storage, atmosphere elements and the thermal advection of North Pacific has been analyzed here on the basis of some variable data from JEDAC, NCEP, SODA and WOCE. Results show that:1. The features of interdecadal variation of upper layer heat storage with a 25-year period are obvious in the North Pacific Ocean. The heat storage anomalies in the central north pacific surrounded by horseshoe pattern.2. Observations of atmosphere elements reveal interdecadal timescale, coherent variations.3. A simple coupled ocean-atmosphere mechanism is built between the upper layer heat process of North Pacific and the Aleutian Low system based on above result.When the upper layer ocean heat accumulates, the sea surface heat-flux is restrained, Aleutian Low is weak, westerly over North Pacific is sequentially weak, the weak westerly makes the sea surface heat-flux weakened further, the upper layer ocean heat accumulate more, that's a positive feedback; weakened westerly reduce the sea surface Ekman transport and the vertical mixing, with the raise of quantity of the upper layer heat, SST raises quickly, the increasing ocean-atmosphere temperature difference increase the sea surface heat-flux, the process of accumulating heat is restrained, that's negative feedback; when the sea surface heat flux becomes normal, the positive feedback disappear, the negative feedback come to the most power, that bring the sea surface heat flux become positive anomaly, upper layer ocean inverse to the process of dissipating heat.The mechanism indicates that the coupled ocean-atmosphere interaction can generate interdecadal fluctuation.4. The flux, heat flux and thermal advection of Kuroshio and Kuroshio Extension character with notable interdecadal variability. The analysis results of sea levelconfirm the interdecadal characters of the flux and heat transport too. Comparing the heat transport with the sea surface heat-flux, we can know that the heat transport is consistent with the coupled ocean-atmosphere interaction mechanism of North Pacific climate interdecadal variation.5. There are two main interdecadal periods in the North Pacific climate system. The short period is 20-30 years and the long period is 50-70 years, which makes the interdecadal variation very complex in the North Pacific climate. When the long period and the short period intersect with the zero swing and the same trend, the regime shift of the North Pacific climate seems to be happened.