Cruise Blog by Frances Cooke: Day 8
July 14th, 2021
Text and photo: Frances Cooke (PhD Candidate in the Gas Hydrates and Free Gas Reservoirs research group at CAGE, working within the SEAMSTRESS project).
The fog cleared during the night while the OBS team were in bed, and the sun shone briefly. We continued the multibeam survey, started two days ago, all through the night, until breakfast. We had an English breakfast this morning, eggs and bacon, but no beans. The final OBS was recovered mid-morning and OBS preparation for the active seismic experiment has started.
If it’s not the strong wind or the fog preventing OBS work – it’s the sea ice! We planned a seismic experiment before the start of the cruise, in the west of Vestnesa ridge. Here we will most likely encounter sea ice. We discover today that our proposed location for the OBS sits within the open drift ice. It would be foolish to take the risk and deploy the OBS, while the charts show drift ice nearby. I am told that deploying the OBS in sea ice is no problem, but when the OBS surfaces it could get stuck beneath the ice.
The Norwegian Meteorological Institute (www.cryo.met.no) provides ice charts and satellite images daily that we can use to monitor the whereabouts and movement of sea ice. The satellite imagery is not affected by cloud cover and can acquire data during the day or night and under all weather conditions.
An ice chart overlaid onto the bathymetry (seafloor map) provides location of drift ice in the Fram Strait. The active seismic planned experiment in the west of Vestnesa ridge is within open ice drift.
The latest satellite image used for mapping of the sea ice (cryo.met.no). The sentinel-1 mission includes a C-band Synthetic Aperture Radar (SAR) sensor that has a resolution down to 5m. Red arrow points to west Vestnesa ridge.
The winds were high in the afternoon, so we continued with multibeam mapping, extending away from our first survey area towards the northwest. Once the ship met the sea ice we decided to abort the multibeam survey, change course and head three hours east to prepare ourselves for the active OBS deployment in an ice free conditions.
For the transit there were fresh wienebrød (Norwegian custard centered pastries). De var gode!
Birds pictured on the sea ice, during the last multibeam survey line, heading northwest, towards the western part of Vestnesa ridge.
Read more about the SEAMSTRESS project here.