Analyzed 44 years of medium-strong turbulence data to understand the impact of climate change and contribute to a safer aviation future
A team of researchers fromNational Institute of Geophysics and Volcanology (INGV) conducted a study, published in Geophysical Research Letters, on the significant increase in air turbulence in European skies, including those in Italy. This phenomenon is closely linked to climate change and can manifest itself in different ways with serious implications for flight safety.
The study looked at data from the past 44 years, focusing specifically on moderate to severe turbulence. There has been a significant increase in such events, particularly over the UK, northern Europe and the Mediterranean region. Convective turbulence, for example, is caused by the vertical motion of air caused by intense heating of the Earth's surface, often associated with the formation of cumulus clouds and thunderstorms. Clear air turbulence (CAT), unlike convective turbulence, occurs without any visible signs and is caused by strong vertical variations in wind speed, usually associated with jet streams.
"CAT appears to be particularly dangerous" explains Tommaso Alberti, INGV researcher, “because it is difficult to detect and predict. This represents a risk for pilots and passengers. There are different levels of turbulence, light turbulence, the most common, can cause small movements without compromising safety, while moderate or severe turbulence (MOG) can cause sudden changes in altitude and/or course, endangering the safety of passengers, thus increasing the risk of structural damage to aircraft. On May 20, Singapore Airlines flight SQ381, while flying over the Gulf of Myanmar, encountered sudden and severe turbulence".
The most significant result of the study concerns the role of the jet stream, in particular the subtropical one. The research has shown that, in the vicinity of this current, the probability of MOG turbulence in clear air has almost tripled during the same period, going from 1.5% to 4%.
"The subtropical jet stream promotes turbulence in the southern regions of European airspace”, continues Alberti, “while the subpolar one is responsible for MOG turbulence events near the UK and areas of Northern Europe. However, the intensity and frequency of turbulence events in the vicinity of these jet streams have increased significantly in recent decades due to global warming. This has led to a greater involvement of the areas affected by the turbulence, with episodes distributed over a wider area. This area extends from the North Atlantic to the Scandinavian regions, up to the central and southern Mediterranean, with Italy also being affected. The effects vary according to the season, more intense in winter and more tenuous during the summer period.".
These results highlight the importance of developing new forecasting techniques and mitigation strategies, in order to improve passenger safety and comfort, thus also reducing airline operating costs. The increase in the frequency and intensity of turbulence continues to have a significant economic impact, and expenses are likely to increase further in the future. By combining climate data from the ERA5 reanalysis and new statistical approaches, the work provides a deeper insight into the role of global warming in atmospheric circulation changes and its effects on airborne turbulence, contributing to a safer and more sustainable future for aviation.
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Figure 1: Comparison of typical conditions (top panel) and climate change-induced conditions (bottom panel) on air turbulence monitored by the Ellrod index TI1 which identifies areas where strong vertical gradients of wind speed develop.
Figure 2: Comparison of typical conditions (top panel) and climate change-induced conditions (bottom panel) on air turbulence monitored by the Ellrod index TI3 which identifies areas where strong vertical temperature gradients develop.