Data

Your access to IMOS New South Wales Mooring data discovery and exploration is through the Australian Ocean Data Network (AODN) Portal.

The PH100, SYD100, SYD140, CH070 and CH100 moorings consist of a bottom mounted TRDI 300 kHz ADCP and a string of Aquatech 520 temperature and temperature/pressure loggers at 8 m intervals through the water column. Below the sub-surface float at SYD100 (and intermittently at PH100) is a Wetlabs water quality meter (WQM) that consists of a SeaBird CTD, as well as measurements of fluorescence, and turbidity (Wetlabs FLNTU) and dissolved oxygen. The BMP moorings consist of thermistor / pressure string only. Temperature and velocity data are recorded at 5 min intervals, while the WQM records 60 burst samples at a rate of 1 Hz, every 15 mins.

In the context of sustained observing, minimising data gaps is critical. Data coverage for the NSW-IMOS array is shown below.

Data return from the NSW-IMOS mooring array from each of the moorings. Temperature, velocity and Biogeochemistry sensors are indicated by T, V and BGC respectively (Roughan et al 2013).

The NSW mooring array was designed to capture the key continental shelf processes along the narrow continental shelf of southeastern Australia. The East Australian Current (EAC) flows southward along the east coast of New South Wales, transporting heat poleward. It drives upwelling in coastal waters and enhances productivity.

EAC Dynamics

Cross-shelf dynamics:

Up to 4 years of measurements from Coffs Harbour and Sydney moorings were used to investigate the cross-shelf dynamics upstream and downstream of the separation point of the EAC. Bottom cross-shelf transport was quantified, showing net onshore transport at all locations, with Ekman theory based on along-shelf bottom stress explaining up to 64% of the temporal variability. Uplift in the bottom boundary layer was more intense and frequent upstream than downstream. At both locations, strong variability was found in bottom water transport at periods around 90–100 days. This corresponds with periodicity in EAC fluctuations and eddy shedding, highlighting the EAC as a driver of variability in the continental shelf waters (Schaeffer et al., 2014).

Seasonality:

It has been shown that the East Australian Current warms and strengthens in the Austral summer. However, its highly dynamic nature results in variability in separation and eddy shedding which may have an a-seasonal impact on continental shelf waters. The seasonal cycle in the temperature accounted for up to 49% of variability upstream of the EAC separation zone (Sydney) and 66% downstream (Coffs Harbour). The same annual harmonic found that only 6% (3%) of the variability in the along-shelf velocity in 100 m (140 m) of water upstream (downstream) of the separation was explained by the seasonal cycle.

Data from the SYD100 mooring showing along and across shelf current, temperature and wind stress during 2011.

References:

Roughan, M., Schaeffer, A., Kioroglou, S. (2013). Assessing the design of the NSW-IMOS Moored Observation Array from 2008-2013: Recommendations for the future. In Proceedings of MTS/IEEE Oceans 2013, San Diego USA.Sept 2013

Schaeffer, A., Roughan & Morris, B. 2013. Cross-shelf dynamics in a Western Boundary Current. Implications for Upwelling. AOM Journal of Physical Oceanography. vol 43. pp 1042-1059, 2013.

Schaeffer, A., M.Roughan,and J. E.Wood (2014), Observed bottom boundary layer transport and uplift on the continental shelf adjacent to a western boundary current, J. Geophys. Res. Oceans, 119, doi:10.1002/2013JC009735