Researchers from the University of Oxford and the Munich University of Applied Sciences used a new satellite method based on the parallax effect to determine the height of the January eruption. They found that the plume it produced reached about 35 miles (57 kilometers) into the atmosphere, with some ash potentially reaching another half a kilometer higher. The researchers also claim that the plume is the first seen to enter Earth’s mesosphere, which begins about 31 miles (50 kilometers) above the planet’s surface. The team’s work was published in Science. read more Typically, the height of volcanic plumes is measured by measuring the temperature at the top of the cloud using infrared satellites. As the top of the cloud reaches the troposphere, where temperature drops with altitude, the height of the cloud could be determined by the temperature at the top as it cools. In the stratosphere, however, temperature increases with altitude, meaning that the temperature of the already hot volcanic cloud—and therefore its height—cannot be accurately calculated. Since the team could not rely on temperature measurements from a single satellite, they used a new method of observing cloud height based on data from multiple satellites. Observation of a high-altitude cloud by a single satellite will distort the true cloud height and cause an incorrect estimate. Instead, three geostationary satellites overlooking Tonga provided the data needed for the team’s calculations, aided by the parallax effect: the phenomenon in which viewing an object from different vantage points makes it appear to change positions. You can experience this for yourself by holding your thumb in front of your face and looking at it with only one eye at a time. your thumb will appear to “jump” in the background. The story continues “It is an extraordinary result, as we have never seen a cloud of any type this high,” lead author Simon Proud said in a press release from the University of Oxford. “Furthermore, being able to estimate height the way we did (using the parallax method) is only possible now that we have good satellite coverage. It wouldn’t have been possible a decade or so ago.” According to Proud and his colleagues, Hunga Tonga-Hunga Ha’apai’s plume reached an altitude of 15.5 miles (25 kilometers) 15 minutes after the eruption and 24.8 miles (40 kilometers) 10 minutes later. Thirty minutes after the explosion, the team observed a plume of ash starting 21 miles (34 km) above the surface and reaching the plume’s record peak, with an estimated diameter of 56 miles (90 km). The researchers look forward to using this observational method to create an automated workflow for calculating volcanic plume heights with multiple satellites, which could create a detailed data set for use by volcanologists and atmospheric scientists. Even the questions that remain about how the plume got so high and what effects it might have had on our climate have yet to be answered. More from Gizmodo Subscribe to the Gizmodo Newsletter. For the latest news, Facebook, Twitter and Instagram. Click here to read the full article.
