Last updated: Saturday 9th December 2017   

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Saturday has been a day of swath bathymetry as the James Clark Ross sits off the pack ice that is between us and Rothera Base on Adelaide Island.  There was the potential for some excitement after lunch when Twin Otter Alpha Zula flew across from Rothera to carry out some science work,  but sadly we were unable to spot the aircraft due to the low cloud base.  All we could manage was to hear it as it passed overhead.

Swath image from our time off Adelaide Island waiting for conditions to improve,  showing scarring of the seabed.  Picture BAS

  This image gives a very good representation of how swath bathymetry works.  This is based on a multibeam system,  which we have fitted on the JCR.

On the hull of the ship is a huge array of transducers,  which are used to transmit and receive the sound wave that is transmitted.  In the case of the JCR there is one set of transducers for transmitting and one for receiving the signal. The transmitted 'ping' will be returned from the seabed and by using some very clever software it can then produce a map of the seabed to either side of the ship.  A traditional echo-sounder has a single transducer and will only give the depth directly below the ship. The deeper the water the further can be seen,  much like a torch beam radiating out.

The science team have a blog about their work on board and it can be read HERE

Noon Position Report Saturday 9th  December  2017 

Latitude: 67 06.04 S
Longitude: 071 14.03 W
Bearing: 291 T, 78 Nm from Rothera
Cruise Number: JR17001
Distance Travelled: 44
Total Distance Travelled: 1868.9
Steam Time: 10
Total Steam Time: 210.6
Average Speed: 4.4
Total Average Speed: 8.9
Wind: Direction ENE, Force 5
Sea State: Moderate
Air Temp: -0.9 C Sea Temp: 0.0 C
Pressure: 974 Tendency (3hrs): Steady

 

Previous updates from the current trip.

Previous updates from my last  trip,  to the Arctic in the summer of 2017

Mike Gloistein
gm0hcq @ gm0hcq.com