Dispatch 20: Mooring A Redeployment and Another Aurora!     Print

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Mengnan Zhao

October 7, 2015

After one day of hard work by the WHOI group, Mooring A was ready for another year in the Beaufort Gyre. The preparation for its redeployment began soon after breakfast – instruments and equipment were positioned on the fore deck, and the anchor waited beside the winch. Today I was once again on the bridge to experience a mooring deployment from this perspective.

In preparation to deploy, instead of coming to a stop at the precise location of Mooring A (75N, 150W), we continued forward for a few nautical miles – Second Officer Mark Gould told me that since the mooring deployment would take about 4 hours, the officers would estimate how far the Louis would drift with the wind and currents during that time, so that the mooring was in the designated location when the floatation sphere (the last component) was released in the water.

In addition to the Bottom Pressure Recorder (BPR), Sediment Trap, McLane Moored Profiler (MMP), Upward Looking Sonar (ULS) and Remote Access Sampler (RAS), we had some exciting new equipment attached to the top floatation sphere – an Acoustic Wave and Current Profiler (AWACS) plus an Acoustic Doppler Current Profiler (ADCP) to measure ocean currents and waves.

Up on the bridge, three telegraphs, corresponding to the three propellers of the Louis, communicate with the engine room to make tiny speed and direction adjustments of the ship throughout the deployment. The bubbler system is also controlled by the bridge, and this was especially important today when we were surrounded by ice – it’s important that the wire over the side does not get snagged in an ice chunk. This is true anytime there is equipment over the side; during a rosette cast, if we spot an ice chunk approaching, we contact the bridge by radio so that they may turn on the bubbler system which releases compressed air from the side of the ship, pushing the ice away.  Today there were no problems and Mooring A was successfully deployed by the skillful scientists, officers and crew.

The highlight of our night was when northern lights showed up in the sky (for the second time this trip!). The aurora this time was not only green, but also decorated by red edges which are apparently very rare. Watching northern lights fill the sky in the Arctic with dear friends might be the most magnificent thing I have experienced in my life.