In Brief
Flight Recorded Volcanic Ash Data Evaluated
When Eyjafjallajökull volcano in Iceland erupted a year ago, air traffic across Europe was terminated on reasons of precaution. The safety concerns were due to uncertainty as to how the volcanic ash would spread in the atmosphere and that it could possibly damage aircraft engines. With its surveying aircraft Falcon 20E, the DLR then began with an encompassing airborne data acquisition and measurement campaign. Now the results have been published, allowing for improved forecasts, so that airspace restrictions due to volcanic eruptions may be kept at a minimum or not become necessary at all in the future.
"The volcano discharged an estimated total of some ten megatonnes ash and three megatonnes sulphur dioxide", says Prof. Dr Ulrich Schumann, Head of the DLR Institute of Atmospheric Physics. "We were able to verify the layer of ash in heights of up to seven kilometres. It ranged between several hundred metres and up to three kilometres in thickness and 100 to 300 kilometres in width." The Falcon performed altogether eight data acquisition flights. During the flights across Iceland on 1 and 2 May 2010, the measured values in the centre of the ash cloud exceeded one milligram per cubic metre.
On 19, 20, 22 April and on 9 May, ash clouds with a concentration below 0.2 milligram per cubic metre were verified above Germany and the Baltic and North Sea. On 17 and 18 May, ash clouds with a concentration of in part exceeding 0.2 milligrams per cubic metre drifted across the Netherlands and Germany, but they are sure to have remained below the agreed limit of two milligram per cubic metre.
The results of the ash data acquisition flights now are used across the globe to reappraise and improve the forecast models. For the future, the aviation industry insists on having the right to make their own decisions regarding flights in the event of volcanic eruptions. To this end, the required risk analysis processes and information need to be ready at hand.
