资源环境科技发展态势分析平台

This study presents evidence of interannual to interdecadal variabilities residing in the subsurface nonlinear dynamical heating (NDH) along the equatorial Pacific thermocline based on ocean reanalysis products. In association with a flattened thermocline and drastic halt of the Equatorial Undercurrent, the NDH increases sharply right after a peak of the strong El Nino, reducing the linear anomalous advective subsurface cooling by 30%. As the result, subsurface cold signals in the west are significantly weakened as it reaches the easternmost Pacific, causing less surface cooling in the east and thus weakening the subsequent La Nina. Therefore, the subsurface NDH contributes to asymmetry in both the magnitude and structure between El Nino and La Nina. The acute positive subsurface NDH associated with strong El Nino events leads to substantial variations in its decadal means and serves as a potential source for tropical Pacific decadal to interdecadal variabilities.