S2 observatory Filchner Ronne

The S2 Observatory for long term monitoring of Ice Shelf Water (ISW) Overflow situated at the Filchner sill in the southern Weddell Sea was established in 1977 and continues to deliver the longest existing marine time series from Antarctica. The position for the observatory S2 proved to be a key site for monitoring the ISW overflow produced beneath the huge Filchner Ronne Ice Shelf and is selected to be a part of the global net of monitoring sites under CLIVAR ( and OceanSITES ( Time series of current speed and direction, temperature and salinity exist back to 1977.  Continuous observation of dissolved oxygen started in 2009.

Infrastructure Location

Study Area

Location Filchner-Ronne Ice Shelf, Antarctica
Distance from Land 200 km
Max Depth 600 m
Oceanographic features of area Long term observations of the flow of dense waters from their area of formation to the abyss of the World Ocean, and the return flow of warm waters, are central to climate research. For the Weddell Sea an important component of such a system entails monitoring the formation of High Salinity Shelf Water (HSSW) on the continental shelf north of Ronne Ice Front, the transformation to Ice Shelf Water (ISW) beneath the floating Filchner-Ronne ice shelf, and the flux of ISW overflowing the shelf break to the deep Weddell Sea. Equally important is the return flow of warm water toward the Filchner-Ronne Ice Shelf system.

Observations at the Filchner sill also show a seasonal inflow of relatively warm water that is able to reach Filchner Ice Front. New model results indicate that this flow of water might increase in the future and we have deployed a number of instrumented moorings in the Filchner Depression to estimate the heat flux towards the ice shelf.

Relevant publications isi journals Foldvik, A. et al., Ice shelf water overflow and bottom water formation in the southern Weddell Sea. J. Geophys. Res. 109 (2004).
Nicholls, K.W., Østerhus, S., Makinson, K., Gammelsrød, T., & Fahrbach, E., Ice-ocean processes over the continental shelf of the southern Weddell Sea, Antarctica: a review. Rev. Geophys. (2009).
Østerhus, S., Monitoring of Bottom Water Formation in the Southern Weddell Sea. CLIVAR Exchanges Nº35 10 (4), 61-63 (2005).
Relevant publications proceedings published in the context of conference

Scientific Researchers

Name Email
Svein Østerhus <Please login to view>

Status / Maintenance

System Status Operational Planned Frequency 24 month(s)
Platform Required Deep Sea Research Vessel, Icebreaker People Involved 1
Duration of Operations 800 day(s) Cleaning Yes
Replacments Yes Download Data Yes

Data Information

Final data output format ASCII Data Quality Check Yes
Type of quality check on real-time/near-real time data Manual Real Time – Data availability target
Type of Quality check on delayed mode data Manual Delayed Mode – Data availability target
Own data management No Type of use of data Research
Data Management Link


Avaliable for TNA Yes
Prefered time period for TNA September 2015 to March 2017
TNA Support offered Basic infrastructure. Technical assistance adding additional sensors or complete monitoring system to the site.
Services Available
Potential Additional Uses
Data Ports RS232, CANBUS
Availability of External Power 25 V
Instrument installation methodology
Data History
Instrument installation methodology Recovery and redeployment from ships
Observatory maintenance estimated or planned schedules
Data policy and access Open
Additional comments
Modality of access In-Person


Deployed 26/01/2013 Planned 15/02/2016
Instrument/Sensor Type Parameter(s) CTD, Currents, DOXY
Platform Mooring Manufacturer Aanderaa
Instrument/Sensor documentation (URL)
Sensor Type / Model Power Supply
Approximate Depth / Height Sampling interval
Calibration Samples Available Yes Frequency of Calibration Samples
Intercalibration Available Yes Intercalibration Platform
Intercalibration Frequency
Solution Adopted
Datasheet URL