The Antarctic ice sheet changes in size over the course of a year, as you can see in this animation. When it is summer in the southern hemisphere (our winter) the ice sheet decreases in size. As the ice sheet melts it releases fresh water into the ocean. In the southern winter (our summer) the ice refreezes, drawing fresh water out of the surrounding ocean, leaving the salt behind. These seasonal changes in the ice sheet can be examined by satellite imagery. NOAA keeps track of what the ice cover is on a daily basis in Antarctica.
Using imagery from the imaging radar used on board the space shuttle, scientists have begun to analyze the thickness (hence the age) of the ice sheet around Antarctica. Sample images and more information are available from NASA's Jet Propulsion Laboratory.
By joining satellite images, scientists have been able to create a single image of Antarctica using the Advanced Very High Resolution Radiometer (AVHRR) on NOAA satellites. More information on this image and its importance are available from an Educator's Packet put together at the Goddard Space Flight Center.
Use an atlas and satellite imagery to examine the geography of the region and the changing boundaries of the ice sheet.
This activity can either be done with tracing paper and clear plastic overlays or using NIH Image as outlined by this activity.
- Trace the different satellite images of Antarctica. Be sure to label the different months.
- Locate the Ross Ice Shelf, Ross Sea, Weddell Sea, McMurdo Station (United States research center since 1955), Mawson Base, Ellsworth Mountains, Transantarctic Mountains, Mount Erebus, West Antarctica, East Antarctica, Antarctic Peninsula, Pacific Ocean, Atlantic Ocean, and Indian Ocean
- Examine the satellite image from winter for differences between the two seasons. On your map draw differences in the ice sheet from one season to the next.
- Discuss why the seasons are different in the southern hemisphere than in the northern hemisphere.
- Determine the scale of your map to calculate how much the ice sheet receded over the course of one year.
Tracking Annual Changes in Sea Ice
Collect a series of images of the Antarctic ice sheet covering a period of several years. Draw the boundaries of the ice sheet over the course of several years and discuss possible reasons for the differences in the ice sheet.
- graphing paper
- satellite images of Antarctica
- colored pencils