Petermann Ice Island Seen from International Space Station

Ron Garan aboard the International Space Station just send this photograph of Petermann Ice Island PII-A down to earth as reported by Jason Major.

Petermann Ice Island PII-A on July-25/26, 2011 as seen by MODIS/Terra and the International Space Station

While the detailed photo indicates that the ice island was about as close to the coast as it is long, it has since moved offshore and to the south. The ice island is on its way to clear the similar sized island of Belle Isle in the middle of a channel that separates Labrador in the north from Newfoundland in the south. The distance from the coast is not all that relevant, but the water depth is. Classical physical oceanography says so and I urge you to watch this MIT movie.

In a nutshell: The rotating earth limits large-scale flows, such as those that propel the ice island, to move in ways that seem to make no sense. More specifically, if there is a tiny change of the bottom depth, then the flow at all depths, and this includes the surface, will want to go around this obstacle to stay with the depth it started at. It is very hard to move water from water 200 meters deep such as on continental shelves to water 2000 meters deep such as further offshore. There are exceptions to this rule, of course, but they involve other forces that usually, but not always, are small.

It is so much fun to watch and predict where this ice island will move next, especially if one can be proven wrong so easily. “The proof of the pudding is,” as Cervantes has Don Quixote say so wisely, “in the eating.”

4 responses to “Petermann Ice Island Seen from International Space Station

  1. So given the water depths in this area what is your prediction?

  2. The ice island will stay to the east of Newfoundland, make to the latitude of St. Johns and the rich fishery grounds of the Grand Banks which also sees a fair bit of oil production inshore of the 1000 meter isobath. I will have to down-load and plot the bathymetric data, but a quick google-search revealed a beautiful map from Shaw (2006) who describes how this shelf evolved over the last many thousands of years that includes the last ice age. I am unsure about copyright issues as this is a Canadian Government publication, but the images are so vivid, that I post them here anyway and let Dr. Shaw know. More to read, more to learn, too much fun.

    This entire area has very good historical data coverage as the livelihood of Newfoundland is tied closely to these two offshore industries.

  3. One interesting aspect is the tabular nature of this iceberg. Most Greenland icebergs are not tabular. This berg also has a shallower draft and hence less freeboard than most as well. This should lead to a bit different behavior.

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