Thursday, December 20, 2007

Sea Ice

The sea ice in McMurdo Sound freezes each year. During the summer, it usually melts all the way up to base. McMurdo's site was originally chosen because it is the furthest point South that a ship can navigate when that sea ice melts. If the ice melted more they could go farther.

A Bassler plane on the sea ice runway.

We use the sea ice for roads and as a runway. Each year, those roads and runway are reestablished. We have another runway on the glacier for after the sea ice melts. We don't use it all the time because it is much farther away and therefore more costly to operate.

Mt. Erebus in the background. The sea ice runway road in the foreground.

Annual sea-ice thickness varies seasonally between 8 and 11 feet by the end of the growth period. Thinning by bottom melting starts about mid-December and continues until breakout in late January or early February. We usually move the sea ice runway out to Williams Field as soon as the melting starts.

A radar bubble on the sea ice runway.

While the sea ice is being used as a runway, the minimum thickness is 70 inches for a C-17 to land on it. The minimum length of the runway is 10,000 feet. There is a 69 page document that goes on and on about the smallest details of what needs to be done. It is more complicated than you'd ever guess. The maximum parking load is 600,000 lbs for 1 hour or 490,000 lbs for 3.2 hours. The most important thing we are monitoring is sea ice temperature because as the temperatures increase the weight of the aircraft is adjusted lower. They also have a surveyor measuring how much the sea ice bends every time a plane lands on it. If it bends too much, they'll decrease the weight on the next plane or close the entire runway.

More buildings that make up part of the sea ice runway facility

What other numbers do I have for you ... The average water temperature is -1.9 degrees Celsius or 28.58 degrees Fahrenheit.

The sea ice runway closed three weeks ago. However, until this week we were still using the sea ice as a road network out to field camps. This map shows our surrounding area and details about the sea ice thickness in early December when we were closing the runway.

Sea ice thickness map.

So I wanted to write about this to convey just how amazing and strong the sea ice is. I'm not sure if I did that, so just think about it again 600,000lbs of plane on eight feet of sea ice equates to 187.5 2008 Toyota Tacomas!!

Next blog should be about my trip out onto the closed sea ice!!


  1. How cool. I can't imagine how meticulously they monitor the sea ice. No one would want to watch a C-17 sink into the sea...well, come to think of it, that might be kind of funny to watch but a huge waste of money. So all in all not good.

    Where's the penguin?!?!?!

  2. How did you happen to know how much a 2008 Taco weighs? Shopping Toyota's website to purchase one when you're back in the states?

    (And yes, I think the facts about the sea ice are facinating!)

  3. I think the newest car I have ever owned was 5 years old with over a hundred thousand miles. After that one, I moved up to cars at least 10 years old. I think that is a trend that I plan to stick to. It's cheaper and keeps me away from car payments. Besides, I probably won't have any money left after I get done traveling :-)