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I’m curious about Canadian Archipelago sea ice area

October 16, 2008

What is happening with the Canadian Archipelago sea ice area?  Like all Arctic regions, the sea ice area of the Canadian Archipelago expands in the winter and shrinks in the summer.  Many people have come believe that the average yearly behavior of the ice from 1979 to 2000 represents what is “normal.  The only special thing about these years is that they are the first 20 years over which satellite data on sea ice area was accumulated.

For the last several years the Canadian Archipelago sea ice area, and the Arctic sea ice area in general, have dropped below the “normal” at least for part of the year.  The headline grabbing stories have been about “first time” openings in the “Northwest passage” through the Canadian Archipelago.  There seems to be a lot of interest, concern and talk.

I have turned to Cryosphere Today, from the Polar Research Group at the University of Illinois, and The Advanced Microwave Scanning Radiometer on the Earth Observing System Aqua satellite (AMSR-E) for my information.  The odd thing is that while Cryosphere Today’s 365 day plot of the Canadian Archipelago’s sea ice area (figure 1, below) indictes that the sea ice area is LESS today than it was one year ago, Cryosphere Today’s own graphics of arctic sea Ice area for 10/14/07 and 10/14/08 clearly show that the sea ice area in the Canadian Archipelago is GREATER now than it was a year ago.  The AMSR-E graphics show the same thing, as displayed in figures 2 and 3, below

Figure 1. CryoSphere Today's plot 365 days of Canadian Archipelago Sea Ice Area from 10/14/08.  Note that this plot shows the sea ice area about 25% greater one year ago.

Figure 1. Cryosphere Today's plot of 365 days of Canadian Archipelago Sea Ice Area from 10/14/08. Note that this plot shows the sea ice area about 25% greater one year ago.

 

AMSR-E data for 10/14/08.

figure 2. Sea ice area representations. Upper Left: Cryosphere Today for 10/14/07. Upper Right: Cryosphere Today for 10/14/08. Bottom Left: AMSR-E data for 10/14/07. Bottom Right: AMSR-E data for 10/14/08.

 

Figure 3.  Same as figure 2, except showing close-ups of Canadian Archipelag0.

Figure 3. Same as figure 2, except showing close-ups of Canadian Archipelago. Note that 2007 data is on the left, and the 2008 data is on the right. These graphics clearly show more ice in the Canadian Archipelago now (on the right) than there was one year ago (on the left).

 What gives?  Am I seeing this right? The ice distribution graphics from both Cryosphere Today and from AMSR-E instrument aboard the Aqua satellite both show GREATER sea ice cover now (10/14/08) than one year ago (10/14/07).  I am just trying to understand this discrepancy.  If anyone has an explanation, please comment below.

By the way, trips through the Northwest passage have been made long before now.  The wooden ship, St. Roch, made it twice in the 1940s.  Roald Amundsen did it even earlier aboard the Gjoa in 1905.  Of course, we do not have satellite data to show us the sea ice in the Northwest passage prior to 1979.  Who knows what could have been done with modern equipment thousands of years ago when the Arctic was warmer than today?

2 comments

  1. Vey nice info, thanks!


  2. Good reading, the answers are sometimes hidden in the questions
    Alan



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