Measuring Volcanic Ash Possible With Space-Borne Laser Instruments

by Tanya Thomas on Jun 1 2010 10:56 AM

 Measuring Volcanic Ash Possible With Space-Borne Laser Instruments
Space laser technology is needed to measure volcanic ash, scientists said at a meeting of some 50 experts in Frascati, Italy, to assess Iceland's Eyjafjallajokull eruption.
Experts believe the information provided by laser instruments can be used to work out ash concentration and determine the risk to aircraft engines.

The US Calipso lidar (light detection and ranging) has been very effective in returning this data.

Currently, the European Space Agency (Esa) is preparing two lidar missions: ADM-Aeolus and Earthcare will be launched later this decade.

Aeolus is designed to study the wind, while Earthcare will profile normal weather clouds.

However, just like the American Calipso spacecraft, these can be used to determine the thickness of drifting ash plumes.

If the vertical profile is combined with the known extent of the plume, a concentration can be arrived at.

The airlines at this time are working to a safe limit of four milligrams of ash per cubic metre of air.

The performance of current space sensors and the requirements for future technologies were discussed during a two-day meeting at Esa's Esrin Earth-observation centre.

The space agency organised the meet jointly with Eumetsat, which operates Europe's weather satellites.

The necessity of space lidar instruments is sure to be featured in the white paper that will summarise the outcome of the discussions at the gathering, said Dr Ken Holmlund, the head of Eumetsat's meteorological observations division.

"Esa will look into its future missions now to see if there is some tweaking that can be done or some additional instrumentation or further improvements that should be taken onboard," the BBC quoted Holmlund, as saying.

He added: "And from a Eumetsat perspective, this really emphasises the crucial role of the Meteosat Third Generation mission which is now being debated. This was a clear message for me that for future volcanic monitoring, you really need good observations from geostationary orbit; and for Europe, it will be MTG or nothing."

In the short term, Dr Holmlund said, existing sensors and data could be used to provide better information to the national Volcanic Ash Advisory Centres (VAACs) which issue the atmospheric warnings to the aviation sector.

He said: "Until now the data from the various missions have been used in isolation.

"We should try more to look at multi-mission approaches, bringing together all the available data in a more effective way to make better products.

"What was demonstrated during this workshop was that the advice that has been given out by the VAACs has been very, very accurate in most cases; and this has been confirmed by aircraft measurements.

"There were a lot of [aircraft measurement] campaigns going out from France, the UK and Germany, and in most cases the ash was confirmed to be where the satellite data saw it and the modelling had predicted it to be. We did a pretty good job."