Using satellite data to track and improve volcanic ash forecasts

Using satellite data to track and improve volcanic ash forecasts

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US: NASA 3D satellite data can be used to improve forecasts of volcanic ash plumes to benefit aviation, according to a new study published in the Journal of Applied Meteorology and Climatology. NASA currently has a number of instruments in space with the ability to “see” volcanic ash. Each of these instruments provides the researchers with information about the ash. This data helps detect, locate and characterise the physical and chemical properties of the ash plume. None of the instruments, however, creates a complete enough picture of the ash plume and its constituents to provide effective information to the aviation community about the threat, but that is changing.

NASA’s CALIPSO (Cloud Aerosol-Lidar and Infrared Pathfinder Satellite Observations) mission is uniquely suited to provide researchers with updated information about ash plume height and location. CALIPSO provides an unprecedented 3D view of atmospheric particles, like volcanic ash, and cloud in the atmosphere using a space-based LiDAR system since 2006.

The research team focused on the volcanic eruption of Puyehue-Cordón Caulle in Chile in June 2011. This eruption disrupted air traffic throughout much of the Southern Hemisphere. This powerful eruption ejected ash in the upper troposphere – 3 to 9 miles above the Earth. Because of the higher ejection, the plume was longer-lasting, circling the globe at least three full times in the southern latitudes.

The data from CALIPSO allowed the researchers to track the plume on its trip around the world. Different channels of the CALIPSO LiDAR were investigated to be able to differentiate between clouds and ash.

“CALIPSO gives us very accurate information about the 3D location of ash,” said Vernier. “However, the CALIPSO LiDAR data comes to us in curtains and we don’t know what’s between two curtains. We use trajectory models to fill in those gaps.”

Volcanic ash observations from CALIPSO were used as initiation points for the trajectory model. It is possible to produce a more accurate forecast than using a simple dispersion model by accumulating several days of observations transported by the trajectory model forward in time.

A key advancement with this technique, according to Duncan Fairlie, research scientist at NASA’s Langley Research Center, was being able to use “cloud clearing” algorithms, or mathematical formulas, developed by Vernier.

Comparing the model results with independent CALIPSO observations showed the team that the model had successfully reproduced the 3D structure of volcanic ash clouds.

Source: Red Orbit