Blog: Painting a coloured image

August 24, 2019, the Ryder expedition

How do you fill a fjord? We do it by mapping. The icebreaker has a Multibeam. It´s an echosounder with many beams that like a scanner scans the seafloor and creates a 3D image of the sea floor. Spectacular to see us moving at the surface painting a coloured image of what is below. So, we fill the image of the seafloor by going back and forth in the fjord. The best is straight lines. Straight lines are best for processing the data. We hardly ever go straight. Ice is blocking our way. There is sea ice and there is glacial ice. The glacial ice comes from the glacier. The Ryder glacier has a floating tongue. 40 km in from the front is the grounding line. From the high plateau the glacier is slowly floating down and at the grounding line it becomes a floating tongue. As it becomes floating it becomes thinner, as the friction to the bottom is lower. At the front, big chunks of the glacier is broken off and floats out in the fjord. One piece we found was 9 km long and 4 km wide and almost 100 meters deep. A heavy piece you do not move even with the strongest icebreaker. So we cannot map where they are. We have to wait, study out satellite images trying to figure out how they move in a pattern driven by currents and wind.

Investigating connecting glaciers

Now we have done all we can. Taken all sediment cores, plankton nets, CTD´s and removed all instruments we set out. We have brought the Land team back onboard and are getting ready to go out on a transect to investigate what´s outside the fjord. How far did the glaciers reach when they were so much bigger and covered most of the area? Did they turn south or north outside the fjord? How did our glacier connect or interact with the others north of us, like the Victoria fjord?

Straight lines do not exist

The ice outside is tough to get through. The mapping is a time-consuming adventure. Straight survey lines do not exist anymore. We are trying to follow the small leads we can find, circle around ice floes and slowly doing our job. We will be in this ice for a number of days yet trying to map our way to the next target box where we will take yet another core, fill more water bottles, cast CTD´s and so on.

Ice looks better on the Canadian side. A polynya has opened up. That might be our next move to try to go there. Speed is low. We are happy to do 2 knots. Travelling here takes time. Lots of time ….

Text av: Ulf Hedman

Sidan uppdaterades: 6 september 2019