The Effects of Decadal Oscillations of the Curl τ = 0 Line on Intergyre Water Exchange and Temperature Variability

Abstract

The effect of meridional movement of the curl τ = 0 line on the intergyre transport is investigated by passive tracer experiments in a double gyre circulation. Furthermore, the contribution to temperature distribution is considered. The nonlinear quasigeostrophic, reduced-gravity model is employed to express a fundamental baroclinic ocean response. Parameter studies show that a decadal wind migration causes the intergyre exchange much more effectively than does an annual wind migration. The efficiency of the intergyre exchange is primarily determined by the wind migration period relative to the necessary time in which a tracer crosses the ocean basin from west to east. The meridional movement of the curl τ = 0 line can induce temperature change through two processes: 1) entrainment of subtropical (subpolar) water into the subpolar (subtropical) gyre along the eastern boundary and 2) a vertical movement of the thermocline propagating as a Rossby wave. The temperature variability is similar to the decadal temperature variability observed in the North Pacific.