Wednesday, July 13, 2011

The Arctic Project

I guess I should explain what I’ll be doing up north. I’ll be working as part of a diverse group of scientists on a small research ship where I'll be the only physical oceanographer. We’re heading out to Cumberland Sound, Baffin Island, Nunavut.

Cumberland Sound is large and very remote. It’s located in a part of the Arctic I’ve never been too but, I hear the surroundings are picturesque. At the surface, the sound is about 250 km long by 80 km wide and littered with little islands. Multiple fjords open into the sound, including Pangnirtung Fjord, which is home to the only human settlement in the area (Pangnirtung) were I’ll be flying into.

Due to the remote location, little physical oceanography has been done in the area (if you know of some work that has been done, please tell me as I’m still looking). This lack of information means we know little about how the water moves beneath the surface and the influence of the bottom topography. Physical water properties, such as mixing, influence the availability of nutrients which in turn affects local fish, bird and mammal habitats. To understand a bit about the critters that live there, we need to take a look at the conditions they thrive in.

A number of processes influence the physical properties of the water in the sound, including tides, fresh water inputs and wind (there are likely other things going on as well). There is a tide gauge in the sound, so I know to expect big tides. Fresh water enters the sound from rivers and/or glaciers – and, as a twist on what happens in more southern locations, the fresh water may be colder than the salty water below. Because, the sound is open to the North Atlantic, it could also be windy. The fact that ice covers Cumberland Sound in the winter may also be important – or at least make winter-time winds unimportant.

The sound’s geometry also plays a roll and I’m having a tough time finding good charts of the area – the one I have looks like it was compiled from sparse lead line and sinker measurements. The bottom of the sound appears pockmarked with deep basins extending past a kilometer in depth. Shallow sills separate the deep areas. Greenland halibut and skate are caught in the deep basins – they must like something about the conditions there. In other locations, deep basins behind shallow sills often lack enough oxygen for life to thrive (with the exception of some specialist bacteria). So at Cumberland Sound, if the fish are using up the oxygen in these deep basins it must be replaced somehow (it’s too deep for plants – light simply doesn’t penetrate into the ocean that far). There may be an unknown deep water renewal process occurring or some completely different explanation.

To get data, I’ve shipped two instruments to use off the ship. One is a CTD profiler, where CTD stands for conductivity (from which salinity is calculated), temperature and depth. My profiler is also fitted with a dissolved oxygen sensor. This instrument is lowered down through the water column where it takes measurements as it goes. When the instrument is back on board, I can download the data to my laptop. My second instrument is a current meter which can measure how fast the water is moving and in what direction based on the doppler shift on a sound chirp bouncing off stuff in the water. This instrument provides a real-time view of the currents every meter down to 100 m (I’m hoping the ship will have a current meter that goes even deeper).

For a longer view, we’ll install a number of instrumented moorings that will stay in place (hopefully) until next summer.

My work isn’t the only science that will be going on. A group of biologist will also be on board to implant tracking devices into various species of fish (maybe even sharks). We’re also planning on doing range testing on the tracking devices. Later, another group of biologists will arrive to further investigate the lives of fish. As always in my line of work, what actually gets done depends heavily on the weather.

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