Submitted by Anonymous on Wed, 12/17/2008 - 08:18
Forums
Oden Antarctic Expedition 08

Hello Jeff,

 After taking a test today my students and I were able to take a look at your journal entries and one of my students remarked on the highly irregular shape of the sea ice at the bottom.  Do you or your team have any explanations for the shape of the ice being this way.  Look foward to hearing from you soon

 Mr. Garippa

Gloversville Earth Science

Thu, 12/18/2008 - 10:10

Jeff Peneston

Mr. Garippa,
First, check out today’s journal (12/17).  I think you will recognize one of the flags being lashed by the fierce Antarctic wind!  I also think you will like today’s little video.
Regarding the uneven bottom of the sea ice, that is a big deal to us.Lake ice back home generally forms when the surface of a lake freezes and you can sometimes see layers of frozen snow and slush on the top and sometimes layers of lake water on the bottom.  But, the bottom is more or less smooth because in most lakes the ice doesn’t move much after it forms.  Most of the 1-2 meter thick sea ice we are finding is actually composed of broken, tilted and overturned blocks of ice that formed as a flat layer on the sea, but were broken up by storms and winds.  The first year floes are broken, mixed up and refrozen several times throughout the 10-11 months they exist each year.  Closer to shore, there is multiyear ice that can be even thicker but the bottom of the ice is often just as jumbled.  Today, our ice core cut through 1.7 meters of ice to reach sea water.  However, just beneath each hole was another layer of ice up to a meter thick that was rafted and floating up against the bottom of the solid sea ice.  And, just for fun, there is up to a meter of snow on top of the ice.  This makes the surface of the sea ice look like a junkyard where you can’t see what is buried under the snow!   
Take care, and keep the questions coming,
Jeff