The Role of Ice in the Ocean: Pt. II: How Do We Measure Ice?

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If all of the ice in the Arctic Circle were to melt, life as we know it would be dramatically different - and not in a good way.

That is why measuring how much is there, how thick it is and how fast the ice is melting -- both on land and in the ocean - is so crucial for understanding what is happening in a changing Arctic. There are three main ways that scientists measure Arctic ice: satellites, aircraft, and on-site, or "in situ" measuring.

It is these multiple observations that provide a more complete picture and story of the ice. Scientists use satellite images to create an outline of the dimensions of sea and land ice, including the Greenland ice sheet. The measurements show how wide and thick the ice is in different regions. 

Some satellites measure small changes in gravity that reveal where ice sheets are losing mass, while others have used lasers to measure the height of ice above the land.

To understand the rate of sea ice melt, scientists have placed submerged buoys, called moorings, at strategic locations in the Bering Strait and farther north. 

Devices are attached to the moorings that collect data on temperature, salinity, nutrients, currents, and the thickness of the ice above it.

Using this data, scientists can calculate how much warm water is flowing north into the region, a potential source of heat for sea ice melt.

To study ice melt on the Greenland ice sheet, scientists also use manned and unmanned aircraft systems. The aircraft carry a digital camera, atmospheric temperature and pressure sensors, an ice-surface temperature sensor and a laser range finder.

The data collected from these instruments allow researchers to create 3D digital elevation models, which help calculate the thickness of the ice sheet. By putting all of this information together, scientists can get a more accurate picture of how Arctic ice is changing both on the land and in the ocean.