The Hawaiian Lee Countercurrent region is characterized by high occurrence of mesoscale eddies and complex flows. The activity of mesoscale eddies in this region is critical for the oceanic and atmospheric circulations, sea-air exchange, etc. The interannual variability of the Eddy Kinetic Energy (EKE) and its mechanisms in this region were investigated using reanalysis data from 1993 to 2020. According to the EKE distribution, two regions were selected, namely off-island and near-island. The results showed the following:
The interannual variation of the EKE is significant in both the off-island and near-island regions. The EKE variation in the near-island region leads that in the off-island region by 12 months, with a maximum correlation coefficient of 0.57.
The interannual variation of the EKE is mainly regulated by baroclinic instability, barotropic instability, transport, and wind stress work. Analysis of the EKE budget revealed that the interannual variation of the EKE in the off-island region is mainly controlled by baroclinic instability variation, whereas that in the near-island region is mainly controlled by wind stress work.
Interannual variations of the EKE are modulated by large-scale signals. The interannual variation of the EKE in the off-island (near-island) region is significantly correlated with the PDO index, leading by 10 (2) months, with a maximum correlation coefficient of 0.85 (0.40).