EarthCARE's view of volcanic plume boosts air safety

Anak Krakatau, a volcanic island known as the "Child of Krakatoa," has been sporadically active since emerging from the sea in the late 19th century. Despite the eruption of Anak Krakatau in September 2022, which led to the grounding of thousands of flights and stranding of hundreds of thousands of passengers, even minor volcanic eruptions can significantly impact air travel.

Volcanic ash can damage aircraft engines, cause stalls, and reduce pilots' visibility by scratching cockpit windows. Toxic gases released can also contaminate cabin air supplies.

To address these risks, a global network of nine Volcanic Ash Advisory Centers (VAAC) provides aviation guidance, with each center responsible for a specific region of the world. When the Anak Krakatau eruption occurred, the Darwin VAAC, operated by the Australian Bureau of Meteorology (BOM), took charge of monitoring the volcanic plume.

In response to the eruption, BOM incorporated EarthCARE's atmospheric lidar (ATLID) data into its monitoring tools. ATLID, a specialized laser instrument, provides unique insights into clouds and aerosols, including their altitude and concentration.

Robin Hogan from the European Center for Medium-Range Weather Forecasts (ECMWF) noted that while ATLID detects aerosols at high altitudes, its sensitivity to large particles means that smaller particles, such as those in a volcanic plume, might not be detected. However, ATLID's data helped forecasters verify that ash was present at altitudes of around 15 km (9.3 miles), which is crucial for aviation safety.

Helen Dacre from the University of Reading suggested that this observation could provide valuable information about the longevity and range of volcanic ash particles, which is currently uncertain.

The detection of large ash particles in the plume by ATLID has significant implications for aviation. Andy Prata of BOM emphasized the importance of following the VAAC's advisories and avoiding flying in the affected area. Shannon Mason from ECMWF stressed the complexity and rapid evolution of volcanic plumes, which include ash, clouds, gases, and aerosols.

With timely observations from EarthCARE, scientists can better understand the vertical structure of these events and provide crucial aviation advice. The data collected by EarthCARE will also contribute to understanding the long-term impacts of volcanic eruptions on climate, as highlighted by ESA's Alex Hoffmann.