On the Track of Detergents and Aerosols
In May 2012, the Zeppelin NT embarked on its biggest scientific mission so far. The objective was to investigate relations between atmospheric chemistry and climate change. As an integral part of the EU PEGASOS project, the Zeppelin NT explores air quality in the European air space in three campaigns headed by Forschungszentrum Jülich that each lasts several weeks. Together with the results from investigations by a total of 26 partners from 14 European countries and from Israel in the PEGASOS project, the findings will provide the basis for climate protection measures throughout the EU. The fist results have been published in the peer-reviewed journal Science in April 2014.
Jülich climatologists already undertook Zeppelin expeditions in 2007 and 2008. The two measurement campaigns convinced the scientists that the Zeppelin NT ideally complements aircraft and fixed ground stations. This is due to its unique flight characteristics. It can float slowly, hover in the air, ascend and descend vertically, and fly for up to 24 hours while carrying measuring equipment weighing more than a tonne. Moreover, it makes the atmospheric layer at an altitude of between 100 and 1000 metres, known as the planetary boundary layer, accessible to researchers. It is precisely in this chemically very reactive, but as yet little investigated region that the fate of most of the pollutants emitted on the earth's surface is decided. Information about this region is therefore necessary to understand the atmospheric processes in detail and to verify model concepts. The Zeppelin can investigate the distribution of trace gases in this layer precisely and flexibly.
This campaign focuses on aerosols in the air and also on the "detergent of the atmosphere", the chemical hydroxyl radical (OH radical). This detergent, which triggers the degradation of pollutants and is thus a measure of the cleaning efficiency of the atmosphere, is continuously recycled in a natural cycle. However, in past years Jülich researchers have come across discrepancies in the prevailing theory with respect to recycling. It is hoped that the Zeppelin flights will clarify the matter, including the following issues related to aerosols: Where do they originate? How do they combine to form larger particles? What chemical and physical impacts do they have on the climate and on air quality? And what part do they play in recycling the natural "detergent"?
The scientists use three different sets of measuring instruments for their investigations. Each set is designed for a slightly different question relating to the behaviour of the detergent and aerosols. Depending on the meteorological and chemical situation in the air layers they fly through, the sets of instruments will be changed during the campaign. In a two-week campaign at Friedrichshafen in November 2011, the measuring instruments were adapted to the interior of the Zeppelin NT and their function tested during flights.
The campaign was launched in May 2012. A team of about fifteen researchers from Jülich, Switzerland, Estonia and the USA accompanied the Zeppelin NT on its three missions. The journey began in Friedrichshafen and continued to Cabauw in the Netherlands. After returning to Friedrichshafen, the second mission then spent five weeks travelling to Italy, where measurements will be taken in the Po Valley and above the Adriatic. In April 2013, the atmospheric researchers will embark on their third mission travelling for two months towards the north heading for Hyytiälä in Finland. Both the mission routes and the measuring stations have been coordinated with existing ground measuring stations. In this way, the researchers can directly compare data from the flight with measurements by scientists on the ground.