Abstract:

Several dataset are used to study the interannual variability of the mesoscale eddies in the ACC (Antarctic Circumpolar Current) region. Analysis of AVISO data (Archiving, Validation and Interpretation of Satellites Oceanographic data) reveals that seasonal variability of EKE (Eddy Kinetic Energy) is barely discernible in this area, but its interannual variability is significant. Analysis of zonal wind stress and the interannual abnormal event of SAM (Southern Annular Mode) shows that maximum/minimum of zonal wind stress occurs around 3 years ahead of EKE maximum/minimum, lag and strength of the EKE response depend on the strength of wind stress anomaly. In addition, we also use ECCOJPL temperature and salinity data to calculate the distribution of baroclinic energy conversion rate in the ACC region. Based on this we analyze the energy transfer between wind field and the background ocean in interannual time scales. Based on the above analysis, we consider that the interannual variability of the ACC mesoscale eddies is contributed to the SAMrelated wind stress, which causes the variation of ACC transport and tilt of isopycnal surface. And this causes the variation of baroclinic energy conversion rate from the background ocean to mesoscale eddy, leading to the interannual variability of mesoscale eddies.

Key words: Antarctic Circumpolar Current, mesoscale eddy, interannual variability, baroclinic energy conversion rate