Installation of Sea State Cameras on the Aurora Australis

On October 9, 2018, we have installed a stereo camera system on the Aurora Australis, the Australian icebreaker, within the AAS project 4431 (CAMPCANN), led by Dr Robyn Shofield (School of Science of The University of Melbourne). The camera will operate from October 2018 to March 2019 and will monitor the ocean surface, including the marginal ice zone, during the supply voyages to Antarctica.

The equipment consists of two synchronised industrial cameras equipped with low distortion 5mm lens, which will record overlapping videos of the ocean surface and sea ice floating on it. Cameras are operated via a laptop computer using an automated acquisition system. An inertial measurement unit (IMU) is installed with the cameras to record ship motion. Using photogrammetry principles, the exact position of the ocean surface can be recovered and the three-dimensional wave motion recon- structed (Benetazzo A., 2006 Measurements of short water waves using stereo matched image sequences. Coastal Engineering 53 (12), 1013–1032); ship motion is removed with the aid of the IMU data. The Waves Acquisition Stereo System (WASS) toolbox developed by colleagues at the University of Venice and CNR is used for post processing.

 

 

Camera were installed on the port side of the vessel and will scan the ocean surface at an angle of 35 degrees with the ship’s heading. About 30m of cables runs along the hand rail to connect the cameras to a laptop computer in the metlab.

It is expected that more than 100tb of images will be recorded during the season (see below an example taken during another expedition), which will provide valuable statistical information on waves and sea ice properties, including probability of extreme waves, ice floe size distribution and ice thickness.

 

 

EGU 2018

EGU 2018

 

Air-Se-ice Lab participated to the last The General Assembly 2018 of the European Geosciences Union (EGU) is held at the Austria Center Vienna (ACV) in Vienna with 3 posters. The conference included a total of 4,776 oral, 11,128 poster, and 1,419 PICO presentations with 15,075 scientists from 106 countries. It has been a great occasion to share the latest news in wave-ice interaction, wave forecasts and CFD modelling.

Drift of ice: an experimental model in a wave-ice flume

An experimental study was set up at the University of Melbourne to investigate continuous and broken ice motion due to waves. For short period waves the continuous ice cover remained unbroken and its motion only included heave oscillations. Increasing the period the continuous ice cover entirely broke up. Broken floes moved both vertically and horizontally.  Heave never vanished but dissipated towards the end of the flume.  Surge and drift are relevant only at the beginning and middle of the flume.

Drift of ice: an experimental model in a wave-ice flume

An experimental study was conducted at the University of Melbourne to investigate continuous ice cover breakup due to incident waves with varying amplitudes and periods. Wave attenuation due to the ice cover was also studied. Results showed that both wave attenuation and ice cover break-up depend on amplitude and period. Long waves break the ice cover entirely while short waves attenuates at the beginning of the ice cover.

Surface waves and currents in the Southern Ocean were measured remotely using the WaMoS II radar on the Russian icebreaker Akademik Tryoshnikov. Wind was gathered from the meteostation available on-board. Using WaMoS spectra as input, a nonlinear phase-resolving model based on the Higher Order Spectral Method (HOSM) was used to compute MonteCarlo simulations of the temporal evolution of the random ocean surface. Approximately 30% of them showed a substantial deviation from the exponential, highlighting a high probability of encountering rogue waves.

 

References

https://www.egu2018.eu/