D. Session II: Southern Ocean Variability
Structure and Evolution of Simulated Antarctic Circumpolar Wave
Tatsuo Motoi
Institute for Global Change Research, Frontier Research System for Global Change, Tokyo, Japan
Antarctic Circumpolar Wave (ACW) was found as interannual variability over the Southern Ocean by analyzing Sea Surface Temperature (SST), Sea Ice Extent and Sea Surface Height anomalies. Previous studies show that ACW has wave number two patterns of these anomalies and propagates eastward with 6-10 cm/s around the Antarctica but are limited to identify ACW signal at the ocean surface due to satellite observations.
Here we analyze the data from 100-year experiment with a R30 global coupled ocean-atmosphere general circulation model to study the ACW signal inside the Southern Ocean. Lagged regression analysis for SST anomalies shows resemble structure and evolution of ACW. Eastward propagating and standing barotropic structure of temperature anomalies are found to penetrate deeply inside the Southern Ocean. The propagating signal has planetary scale and wave number two pattern corresponding to ACW. The standing signal might be caused by the topographic perturbation. Ocean sub-surface (50-600m) heat content anomalies are clearly showing the eastward propagating and perturbed structures of ACW within the Southern Ocean.
