| The North Pacific Low Latitude Western Boundary Currents (NPLLWBC) plays a quite important role in meridional transport of mass, heat and salt in the world ocean circulation. It connects the Tropical Gyre (TG) and Subtropical Gyre (STG) and forms the NMK system. Thus studies on spatial and temporal characterizes of NMK system as well as its mechanism are significant in both theoretical consideration and practice. Spatial and temporal distribution characteristics of NMK system and its connection with ENSO cycle are analyzed using a fifty-year high resolving simulations of OFES (OGCM for the Earth Simulator). The results are as follows:First, the characteristics of NMK systems can be well described by the OFES compared with T/P data and in-situ observation data. The variability of the eddy structure in the source area of Kuroshio, MUC, LUC and the eastward current under the NEC is well described as well.Second, The NMK system has obvious seasonal and interannual variability signals. In the seasonal timescale, the whole NMK system has a maximum transport in spring and a minimum transport in fall. The NEC and KC has 2-7 years ENSO cycle period whereas the MC has a quasi-biennial oscillation; during the warm phase of ENSO cycle, the NMK system has a bigger transport whereas during the cold phase, it has a smaller transport. ENSO cycle has a bigger impact on NEC, KC than MC. The correlation between distribution rates of KC and MC in negative. Distribution rate of MC are bigger during El Ni?o years while distribution rate of KC is bigger during La Ni?a years. The NEC bifurcation latitude (NBL) has similar variability signals as NMK system and it lags Ni?o 3.4 index for about 4-6 months. Reasons for this signal are the datelines of zonal wind stress curl. It decides the location of NBL. The reaction time scales are changed with depth, in the seasonal timescale, about one month in the surface and increase to four months in the bottom.Third, the linear impact of ENSO cycles to NMK is complied by SST anomaly and its related atmospheric remote teleconnection. During the warm phase of ENSO, the warm anomaly in the eastern pacific extends northward, at the same time, there is a westward wind anomaly in North Pacific Current zone. It converses to a northward wind anomaly with California Current and finally changes to eastward wind anomaly in the source area of NEC. The NEC transport is thus bigger as well as the North Pacific Current. Because the NEC decides the KC and MC, the whole NMK system is stronger during El Ni?o as well as the STG. During La Ni?a years, it is just reversed.Fourth, the nonlinear impact of ENSO cycles to NMK is complied by local effects near the western boundary. The positive transport anomaly of the whole NMK system during El Ni?o is much bigger than the negative anomaly during La Ni?a. NBL has similar feature. In the cross-section of MC, the decreasing trend is not so obvious during La Ni?a years due to the NBL change and asymmetry structure, whereas the KC is not so. The pacific SST has similar nonlinear asymmetry structure. The center of warm anomaly is mainly located in the eastern pacific during El Ni?o while the center of cold anomaly is located in the center pacific during La Ni?a. This trend is strengthened in the last fifty years. The SST anomaly will lead to zonal wind stress anomaly and finally influence the NMK system. There will be a positive anomaly in the center pacific and stimulates an anomaly cyclone atmospheric circulation near the Philippine islands during El Ni?o years, however, during La Ni?a years, the negative anomaly in the center pacific will move to northwest. Negative anomaly will restrain the anti-cyclone atmospheric anomaly and thus leads to a smaller decrease of transport, the NBL has similar feature. This can be seen in the third mode of nonlinear analysis. The wind stress curl has similar distribution and contributes to different impacts on NMK system during ENSO cycles.
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