During a descent in Brisbane on May 4, 2024, unexpected severe turbulence injuring crews and passengers on a Qantas Boeing 737. Subsequent investigations by the Australian Transportation Safety Agency suggested that the severity of the turbulence surprised the captain.
This is not an isolated event. Thunderstorms featuring violent upstreams and violent gusts of winds, such as downbursts, are dangerous to aircraft. Downburst in particular is known to cause many serious accidents.
Our new research suggests that global warming increases the frequency and intensity of gusts of wind from thunderstorm “downbursts.”
Machine learning technology was used to identify climate drivers and cause downbursts of thunderstorms. Increases in heat and moisture in eastern Australia have been found to be important components.
Findings suggest that aviation safety authorities and airlines in eastern Australia must be more vigilant during takeoffs and landings in the warm world.
Qantas annotated by ATSB
Warm and humid air writes about plane troubles
Global warming increases the amount of water vapor in the lower atmosphere. This is because warming at 1°C allows the atmosphere to retain 7% water vapor.
The excess moisture usually comes from adjacent warm waters. It evaporates from the surface of the sea and nourishes clouds.
Increased heat and steam lead to stronger thunderstorms. Therefore, climate change is expected to increase thunderstorm activity in eastern Australia
For aircraft, the main problem with thunderstorms is the risk of rapid changes in wind strength and direction at low levels.
Small but powerful
Small downbursts, a few kilometres wide, are particularly dangerous. These “microbursts” can cause sudden changes in the speed and direction of wind gusts, causing turbulence that suddenly moves the plane in all directions, both horizontally and vertically.
Microburst gusts of wind can be very strong. Brisbane Airport recorded microburst gusts of wind at 157km per hour in November 2016. Three planes on the runway were severely damaged.
Aircraft encountering microbursts on descent or ascend can experience sudden, unexpected losses or high gains. This has resulted in many aircraft accidents in the past. Microburst will become an increasingly problematic in warming climates.
Microburst analysis and prediction
Microbursts are very small and are extremely difficult to predict. Therefore, machine learning was used to identify environmental factors that most contribute to the formation of intense gusts associated with microbursts.
We accessed observation data from the extensive archives of the Meteorological Bureau. We then applied eight different machine learning techniques to find the best one.
Machine learning is the field of research in artificial intelligence using algorithms and statistical models, allowing computers to learn from data without explicit programming. As the system incorporates more information, it allows the system to identify patterns, make predictions, and improve performance over time.
Atmospheric conditions in eastern Australia are found to be increasingly supporting the development of stronger and more frequent thunderstorm microbursts.
We investigated the occurrence of microbursts from the storm front in 2018. Six regional airports in New South Wales produced severe surface gusts at six regional airports: Burke, Walgett, Conamble, More, Naraburi and Ganeda.
Regional airports in Australia and around the world often use small aircraft. Small planes with 4-50 passenger seats are more vulnerable to powerful, extreme wind gusts produced by microbursts of thunderstorms.
Wide range of results
Our extensive local case studies identified weather patterns that produced severe thunderstorms in eastern Australia during warm months.
If the cloud water content is high, a (downward force) (https://repository.library.gov/view/noaa/11215) will be created in the cloud. This force induces a downward air current. When heavier air reaches the ground, gusts of wind will spray in multiple directions.
Mehmood, K., et al (2023) fluids. ,cc by
These gusts of wind put the aircraft at risk during takeoff or landing. This is because rapid wind changes from tail wind to head winds can lead to aircraft dangerously gaining or losing altitude.
Our analysis highlights the increased aviation risk of increased air turbulence from thunderstorm microbursts in eastern Australia.
Small aircraft at inland regional airports in southeastern Australia are particularly vulnerable. However, gusts of winds generated by these sudden microbursts require surveillance by major East Coast airports such as Sydney and Brisbane.
AAP Image/Dean Lewins
Beware of increased microburst activity
Flying has long been recognized as a very safe mode of travel, with an accident rate of just 1.13 per million flights.
However, the number of passengers around the world has increased dramatically, meaning that even a slight increase in risk can affect many travelers.
Previous studies on risks to climate-related air travel have tended to focus on high altitude cruise risks, such as clear air turbulence and jet stream instability. In contrast, low levels of ascending and falling risks are less emphasized.
Our study is the first to detail the increased climate risk to airlines from thunderstorm microbursts, particularly during takeoff and landing. Airlines and aviation safety authorities need to predict stronger microbursts. In our ongoing warming climate, gusts of wind turbulence is expected more frequently in eastern Australia.
