Creating a Time Series Visualization of Two Decades of Changes in a Glacier

Greenland’s Helheim Glacier has become the center for researchers and glaciologists who are hoping to learn more about the behavior and composition of the glacier. New technology has allowed scientists to map, measure, and track the movement of the glacier using visual scanners and other mapping tools. Over time, scientists are hoping to create a fully functional, 3D model of the glacier in order to see how the world around the glacier impacts it.

NASA created a mission to map the Helheim glacier called IceBridge, which also works to map glaciers in Antarctica. The mission uses aircraft equipped with radar, lasers, and high-resolution cameras to image the glacier. NASA also utilizes instruments like the Airborne Topographic Mapper, a laser altimeter, and the Digital Mapping System cameras. The Canadian Space Agency also utilizes its Radarsat Satellite to assist with the IceBridge missions every year.

The Helheim glacier is of interest to scientists because of its rapid changes over time. In the 20 years of the IceBridge missions, Helheim has advanced and retreated, in addition to increasing how much ice it is putting into the ocean. Between 2000 and 2005, the glacier retreated at a quicker pace than it had in previous years.

Retreat of the Helheim Glacier between 2001 and 2005. Images from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite.

Retreat of the Helheim Glacier between 2001 and 2005. Images from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite.

Using the date compiled by the Airborne Topographic Mapper and the Digital Mapping System, NASA has created a time lapse of the changes experienced by the Helheim glacier. Using this data, NASA can extrapolate potential information regarding sea levels, climate change, and other factors that influence the growth or decrease of a glacier.

NASA has been running the IceBridge mission for 20 years, and in that time technology has improved rapidly. When the imaging technology was first put together, it weighed nearly 4,000 pounds. Now the equipment weighs 400 pounds and can be put onto smaller aircraft to image the glacier.

One of the instruments that has been used on the project is the Airborne Topographic Mapper, or ATM. ATM uses lasers to map the elevation of the glacier. The ATM measures the glacier along a center line, as this area is the most consistent with the movement and characteristics of the rest of the glacier. Using this information, the glacier’s elevation can be compared year to year and the density of the glacier can be extrapolated.

The laser scans the glacier in a circular pattern. The lasers now fire quicker than ever, which gives the computer more information to work with. The laser formerly transmitted 2,000 pulses per second, whereas the modern version of the ATM can fire pulses 10,000 times a second. This allows the map to have more detailed information contained in it. The laser is also accurate up to 2 inches on the surface of the glacier. The computer is able to measure the time it takes for the laser to bounce off the glacier and get back to the aircraft. Combined with camera imaging, researchers can create an animated model of the glacier to visualize changes in it over time.

The images also capture the glacier calving, and the amount of ice being lost to the water is calculated. This way, researchers can detect how much the glacier is moving and how much of the ice is melting into the ocean. This is useful information for figuring out how and why the glacier may be calving more at certain times instead of others.

Using the ATM and the Digital Mapping Systems instruments, NASA can track changes in the Helheim glacier incredibly accurately and allow researchers to see how the glacier is changing over time.

You can see the results of the time series visualization in this video:

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