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Pine Island iceberg under midnight sun

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December 29, 2017

In September 2017, a new iceberg – named B-44 – calved from Pine Island Glacier — one of the main outlets where the West Antarctic Ice Sheet flows into the ocean. Just weeks later, it shattered into more than 20 fragments.

NASAs Landsat 8 satellite captured the above image of the broken iceberg near midnight local time on December 15, 2017.

Scientists say that an area of relatively warm water, known as a polyna, has kept the water between the iceberg chunks and the glacier front ice-free. In fact, NASA glaciologist Chris Shuman suggests that it’s the polynya’s warm water that caused B-44’s rapid breakup.

Scientists used parameters in the satellite’s midnight image to calculate the iceberg’s size. Using the azimuth (an angular measurement) of the sun and its elevation above the horizon, as well as the length of the shadows, Shuman has estimated that the iceberg rises about 49 meters (161 feet) above the water line. That would put the total thickness of the iceberg — above and below the water surface — at about 315 meters (1,033 feet).

This animation combines five Landsat 8 views of B-44 acquired over the past four months (September – December 2017). Image via NASA.

Eleanor Imster

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About the Author:

Eleanor Imster has helped write and edit EarthSky since 1995. She was an integral part of the award-winning EarthSky radio series almost since it began until it ended in 2013. She and her husband live in Tennessee, where they enjoy guitar playing and singing. They have 2 grown sons.