Remotely Gathered Data May Prevent Airline Delays

Photograph: JON GUSTAFSSON/AP

Grounded flights are a nightmare for travelers, especially when traveling internationally.  The 2010 eruption Eyjafyallajökull in Iceland resulted in a week-long travel ban across Europe.  Over 100,000 flights were cancelled, costing airlines US$1.7 billion.

Planes were grounded due to the destructive interactions between ash particles and jet engines, which could cause the engines to stall when the glassy ash melts in the engine.  The International Civil Aviation Association (ICAA) institutes a no-fly zone in areas where the ash concentration exceeds 4 milligrams per cubic meter of air space.  Currently, a conservative approach is taken for determining the no-fly zones, but it is expensive and may be overkill.  Better methods for determining the location of ash would allow for more tightly constrained bans and less interruption to aviation.

The ash concentration and the predicted spread of the ash cloud are determined from source parameters like the rate of eruption and ambient wind conditions.  These parameters are normally inferred from satellites, radar, and ground observations.  However, in the first hours of any eruption, accurate values of these parameters are usually unavailable and the destructiveness of eruptions means that we cannot directly sample them even if we could get a scientist there fast enough.  A paper published in Earth and Planetary Science Letters in March 2013 has addressed this problem by using infrasound and thermal imaging to determine these source parameters.

Infrasonic monitoring and thermal imagery are remote sensing techniques that allow scientists to safely monitor volcanoes without any direct contact with the volcano and ash cloud.  Infrasound records sound waves whose frequencies are too low to be heard with the human ear. Thermal imagery, or heat sensing, detects the heat emitted by an object.  Infrasound recordings were combined to identify consistent jumps in low-frequency sound that result from changing pressures at the vent.   These jumps in pressure are used to calculate the acoustic speed.  When combined with thermal imaging, they determine that the acoustic speed is equivalent to exit velocities at the vent. Knowing the exit velocity and the radius of the vent, the scientists were able to calculate the eruption rate.

By using remote sensing techniques, scientists can more quickly gather the data they need. The eruption rate is used determine the amount of volcanic material being erupted into the atmosphere.  The scientists can use atmospheric models to predict where the ash will go and how much of it will be there, allowing the ICAA to better constrain the no fly zone for planes – great news for all of us hoping to travel safely.

Original article: Ripepe, M., Bonadonna, C., Folch, A., Delle Donne, D., Lacanna, G., Marchetti, E., Huskuldsson, A., 2013. Ash-plume dynamics and eruption source parameters by infrasound and thermal imagery: The 2010 Eyjafjallajokull eruption. Earth and Planetary Sciences Letters. 366. 112–121.

Synopsis by Meghan Fisher