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Arctic Diary – Navigation Experiments - April 2003

We have returned to Alert this year to do some more experiments with navigation and surveillance devices that use the Global Positioning System (GPS). We are at least 4000 km from our hometowns in southern Canada, and traditional compasses don't work here because magnetic north is actually south of us.
A GPS receiver gets radio signals from several satellites at once, and triangulates this information in order to tell us exactly the latitude, longitude and altitude of our position on earth. With this information and a map of the area, we can safely navigate throughout the Arctic.
Early Arctic explorers on Ellesmere Island had to rely on inaccurate maps and traditional navigation devices that used the sun, moon and stars. On repeat voyages, they may have recognized unique characteristics of the Arctic landscape to help guide them on their way.
When early explorers went searching for new land in Canada's Arctic, some of them were fooled by mirages that looked like cliffs in a distant landscape. We saw this effect, which is caused by the sun's rays traveling through air above the ice surface that is undergoing a rapid change in temperature. Since light travels slightly faster through warm air than through cold, the light rays become curved and objects on the horizon can appear taller and distorted.
Since there is no smog near Alert to give us atmospheric perspective, the distant hills seem closer to us than they really are. There are no buildings or trees, so only our tents give us an idea of scale and distance in the landscape.
GPS systems are essential to us when the weather is so overcast that we cannot even see any of the familiar landmarks en route to our ice camp. The sky and the snow look the same and we have to travel very slowly by snowmobile to avoid running into ice chunks in our path. In other areas of the world, a sandstorm in the desert would also create a similar problem for soldiers, who would use GPS receivers to navigate in unfamiliar terrain.
During our stay at CFS Alert, Canadian Forces personnel did a practice drill in fire and rescue techniques. If a real emergency occurred, they might use GPS to navigate to the site of an accident during snowstorm conditions.

During our flight home in a Hercules CC-130 aircraft, the flight crew uses an inertial navigation system to know where we are going. A gyroscope that measures the angle of the plane in all directions works together with an accelerometer that measures the distance traveled in all directions. GPS receivers are often incorporated into flight navigation systems for increased accuracy.

Summer at CFS Alert - July 2002 / Arctic Diary