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First field team update and images direct from the ice!
Antarctica 2010 Newsletter #4 and Photo Gallery (below)
The field team has sent an update and images from the first week of activities - and by the looks of things its been quite a busy and exciting first week!
In order to drill the large ice hole required for UBC-Gavia a large Pisten Bully drill was initially used but the team ran into some troubles. The issue was the slow drilling speed (it took about 8 hours to cut three quarters of the way through the 2.5m thick sea ice) and they sheared two of the 4 drive bolts off of the flange. The team spent much time discussing options and decided to send Martin Doble to Scott Base to make a t-cutter for the hot water drill (inspired by a design by Arctic veteran Ron Verrall). While he was gone, Craig Stevens, Brett Grant and Alexander Forrest ran the Seamor ROV through the first hole they had melted out that morning to inspect the area. They were able to visually inspect the underside of the sea ice in the area that they were planning on flying the AUV. They were satisfied that it was all relatively flat, first year ice - i.e. no large ridges that could be obstacles for AUV missions. The team then ran the ROV up to the sidewall of the 50m+ Erebus Glacier Tongue and got a glimpse of things to come...! A special thanks goes out to Seamor Marine for providing the ROV that captured the incredible image of the underwater wall of the glacier (see the photo gallery below).
After dealing with the challenges of calibrating the ADCPs (acoustic doppler current profilers) internal compasses in a location south of the magnetic pole, our team had their first observations of flows in the region. They have seen a lot of flow variability (even more than they expected). This is almost certainly due to the presence of glacier. In particular vertical flows are comparable to horizontal flows which is very unusual in ocean flows. The 300 kHz ADCP is right next to the glacier tongue sidewall and is showing big vertical flows …60 cm/s at times! This is likely a result of some form of wake effect from tidal currents flowing around and under the floating glacier - which is one of the very subjects the field team is in Antarctica to study.
With the use of the hot water drill the AUV ice hole was finally finished...only to be occupied by seals almost immediately! As if the Antarctic conditions weren’t challenging enough for researchers, the local wildlife has decided to make things even more interesting. The camp was later inspected by a line of penguins on the march!
UBC-Gavia has now been successfully deployed several times. The team is having some trouble with the low backscatter properties of the very clear water - not enough plankton or suspended sediment in the water to reflect acoustic signals - thus making it difficult for the ADCPs on the AUV to measure current velocities. This combined with the high flows shown by the moored ADCPs is making for a challenging AUV deployment environment. But so far the team has been able to troubleshoot any challenges and research is progressing according to plan.
Another member of the team not previously mentioned is Dr. Tim Haskell. Tim is a veteran Antarctic researcher and recently joined the likes of famous Antarctic explorers in the honour of having a geographic feature named after him. Haskell Strait lies beneath the permanent McMurdo Ice Shelf and has Scott Base on its shores. It lies between Cape Spencer Smith and Cape Armitage which were named after two explorers of the Heroic Age of Antarctic exploration. It is a great privilege to have a researcher with Tim’s experience and expertise on the ice.
Three American researchers have also joined the field camp; Tim Stanton, Miles McPhee, and Jim Stockel. Hopefully we will get an update from them in the coming weeks describing the work they are doing on the ice.
Our team is currently in a 24 hour deployment phase, repeating instrument deployments every few hours in order to capture the effects of a full spring tidal cycle. We look forward to sharing more news in the coming week!
All the best,
Andrew
Thursday, October 28, 2010