Spatial and temporal distribution of the wind-induced internal wave energyavailable for deep water mixing in the North Pacific

Using a three-dimensional multilevel numerical model, we examine the distri bution of the wind-induced near-inertial internal wave energy in the North Pacific. Energetic low vertical mode near-inertial internal waves are excit ed at 30 degrees-45 degrees N in the western and central North Pacific by t raveling midlatitude storms during winter and at 10 degrees-30 degrees N in the western North Pacific by tropical cyclones during fall. Thus excited i nternal waves propagate equatorward down to 5 degrees-15 degrees N, where t heir frequencies are twice the local inertial frequencies. Parametric subha rmonic instability can then transfer their energy across the local internal wave vertical wavenumber spectrum to small dissipation scales. The calcula ted results show that low vertical mode double-inertial frequency internal waves are very weak at the times and locations of previous microstructure m easurements, which suggests that the observed value of diapycnal diffusivit y of similar to 10(-5) m(2) s(-1), an order of magnitude lower than require d to satisfy the large-scale advective-diffusive balance of the thermohalin e circulation, may not be representative.