Response of Southern Ocean circulation and chlorophyll to the Southern Annular Mode over the period 1990-2012 from observations

• Main Authors: Panassa, Essowe, Hauck, Judith, Völker, Christoph, Hoppema, Mario, Wolf-Gladrow, Dieter
• Format: Conference Object
• Language: unknown
• Published: 2015
• Subjects: Southern Ocean
• Online Access: https://epic.awi.de/id/eprint/38801/; https://hdl.handle.net/10013/epic.46332

The positive trend in the Southern Annular Mode (SAM) perturbs circulation and biology in the Southern Ocean (SO). We aim to provide observational evidence of the SAM effect on SO circulation for 1990-2012 using Argo data. Preliminary results indicate immediate but seasonally different changes in Mixed Layer Depth (MLD) and Sea Surface Temperature in response to SAM. A marked effect of the summer SAM signal on the Southern Ocean SST is visible. We observe a positive trend in yearly mean MLD since 2000 (ΔMLD about 5 m/13 years) and an elevated inter-annual variability in MLD anomalies since 2005, especially in mode water formation regions. Further investigation revealed that SAM and winds can only partly explain MLD changes. In contrast, the changes in MLD anomalies are strongly correlated with observed salinity changes. The impact of MLD changes onto chlorophyll concentrations as a proxy for biological productivity will be presented.