Antarctica is a very challenging environment to study, with a forbidding climate and terrain. Most field research is limited to the summer months because the Sun doesn't rise over the horizon in the winter. Even taking pictures of Antarctica from space is tricky due to the reflectivity of the snow and ice and to the cloud cover that can obscure the view.

Perhaps it should come as no surprise, then, that new data available to glaciologists have caused them to revise upward the rate of glacial melting and increase in sea levels from their 2007 predictions. A new high-tech map promises to change the state of Antarctic research. Offering the most detailed and geographically accurate map of the planet's southernmost continent, the Landsat Image Mosaic of Antarctica, or LIMA, features virtually cloudless, true-color views of the continent.

LIMA is made from more than 1,100 high-resolution satellite images that have been digitally stitched together. Most images were collected between 1999 and 2003. This free downloadable mosaic provides researchers, educators, and the general public a resource that can help them better visualize Antarctica and the changes affecting its landscape and seascape. As the interactive activity demonstrates, researchers can use LIMA to detect the motion, speed, and direction of flowing Antarctic ice. They can also gauge how these factors may be changing in response to other environmental conditions. LIMA can also be used in other fields of study, including biology, and even help plan fieldwork.

To create the mosaic, a research team sorted through thousands of satellite images, or scenes, taken of different areas of the Antarctic landscape. For clarity, they chose scenes with no more than 10 percent cloud cover. To ensure a consistent image quality across the entire mosaic, the team had to correct for variables such as brightness and shadows. For example, because sunlight strikes Antarctica's surface at a low angle, the outer edges of the continent appear brighter than areas closer to the South Pole. This low-angle light also casts long shadows, which can obscure surface features. The LIMA team enhanced the selected scenes, balancing brightness and color quality and eliminating shadows and glare. Finally, the team used custom software to merge the scenes, following natural features where possible to trim the boundaries between scenes and eliminate seam lines, as seen in the Flying Tour of McMurdo Area video in this interactive activity.

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