Deployments

Deployment of the moorings has varied with time, with the SAZ mooring deployed for the first time in 1998. The biogeochemical Pulse moorings had several deployments that were used for development (2007 to 2011). In 2011 a duplicate mooring was built to enable at-sea turn-arounds. The Pulse moorings are swapped over on roughly an annual basis, depending on ship availability. The Southern Ocean Air Sea Flux mooring was deployed in 2010, with a duplicate flux mooring deployed for the first time as SOFS-3 in July 2012. This allowed for a continuous record of flux measurements at the site. The air sea flux mooring is swapped over on a roughly annual basis.

Temporal distribution of the growing observational assets generated by the SOTS mooring program. Filled, open and dashed bars indicate past, foreshortened (by lack of ship availability), and current deployments.

Each of the moorings required some development to overcome engineering and technical requirements for operating consistently in the high seas, strong current and severe storms that dominate the sub-Antarctic Zone.

SOTS (red star) is located in a low current region, north of the Subantarctic Front (SAF) that marks the northern edge of the Antarctic Circumpolar Current (see Figure 1). SOTS is located in deep waters (>4500 m) west of the Tasman Rise (the shallow region south of Tasmania; with waters less than 2000m deep shown in blue). SOTS exhibits oceanographic properties representative of the Australian sector of the Subantarctic Zone (from ~90 to 145 E; Trull et al., 2001). Waters flowing southward in the East Australian Current reach this region by transiting through channels in the Tasman Rise (Herraiz-Borreguero et al., 2011; from which this figure is adapted).

Between 2010 and 2011 iRobot ocean gliders were deployed at the Southern Ocean Time Series site to traverse a line from the Southern Ocean Time Series site back to the Tasmanian coast.  The glider deployed in March 2010 successfully completed its mission after being recovered in June 2010 but a second deployment in April 2011 had some technical issues. The glider work is now on hold until methods are developed to ensure that they work successfully when deployed from the Southern Ocean Time Series site.

Deployment of a sediment trap