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Scientists Track Sub-Surface Waves to Detect Sea Temperatures

When most people think of waves, they think of waves that can be seen off the ocean shore. However, internal tides or waves are those located deep below the surface of the ocean.

“You cannot see internal waves by eye,” Zhongxiang Zhao said. “Oceanographers can detect the weak sea surface signals by satellite altimetry, which measures the sea surface height accurately.”

Zhao is a principal oceanographer at the UW Applied Physics Laboratory whose work focuses on using satellite data to measure ocean warming. The latest breakthrough in the Zhao lab is the technique called internal tide oceanic tomography (ITOT), which uses internal tides to track ocean temperatures.

Internal waves rub on ridges on the bottom of the ocean, moving back and forth. The movement of internal waves actually changes the height of the ocean surface by a few centimeters. These tiny changes in the ocean’s surface can be detected by satellite altimeters orbiting the Earth. According to the National Oceanic and Atmospheric Administration (NOAA), satellite altimeters measure the ocean sea surface height by measuring the time it takes a radar pulse to make a round-trip from the satellite to the surface and back.

John Lemieux

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