Airborne laboratory presented to research community, new horizons for earth system science, DFG priority programme broadens university research capacities

The airborne research platform "High Altitude and Long Range Research Aircraft" (HALO), co-funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), is ready for takeoff. The German Federal Minister of Research, Professor Annette Schavan, presented the research platform to the science community in Oberpfaffenhofen on Monday, 20 August 2012. Since 2007, the DFG has provided approximately 15 million euros in funding to the project through its Priority Programme "Atmospheric and Earth System Research with the High Altitude and Long Range Research Aircraft". This funding enables German universities participating in the Priority Programme to use the research platform for a wide range of research purposes. HALO is expected to open new horizons in Earth systems science and to particularly enhance our understanding of climate processes.

A joint initiative of German research institutes for environmental and climate studies, HALO has also received funding from the German Federal Ministry of Education and Research (BMBF), the Helmholtz Association, the Max Planck Society, the Leibniz Association, the Free State of Bavaria, the Helmholtz Centres in Jülich and Karlsruhe, the GFZ German Research Centre for Geosciences, and the German Aerospace Centre (DLR). While the aircraft itself is operated by the DLR, individual missions are conducted under the aegis of the various participating universities and non-university research institutions, which undertake collaborative research with national and international partners.

HALO is a unique airborne research platform with a maximum altitude of 15.5 kilometres and a range of over 8,000 kilometres. The aircraft can remain airborne for over ten hours and is capable of reaching the remotest parts of the globe – from the poles to the tropics. Initial test missions have already proven the aircraft's utility as a key research instrument in the fields of geophysics, geodesy, geology and general Earth observation. HALO will be used to study climate related phenomena such as atmospheric chemical processes, which are changing as a result of increases in the emission of pollutants on the ground and from aircraft. The measurement equipment on board the aircraft is able to identify and quantify atmospheric elements in the troposphere and lower stratosphere, including aerosols and greenhouse gases. Among other impacts, these are known to influence changes in the climate, extreme weather events, ozone depletion and the atmospheric energy budget. The data gained will be used in climate projections and atmospheric modelling with supercomputers. HALO will also enable researchers working on space missions to combine data from orbital research platforms with atmospheric data, and to test and validate remote sensing methods.

"In future, thanks to HALO's long range and large payload, we will be able to fly major missions without the need to plan for costly and timeconsuming stopovers. The aircraft's generous maximum height will also allow us to conduct analyses of the tropical tropopause for the first time ever. This is expected to greatly enhance our understanding of both Earth system science and climate change," explained DFG Priority Programme Coordinator, Professor Joachim Curtius, from the Institute for Atmospheric and Environmental Sciences of Goethe University in Frankfurt am Main.

The use of aircraft as research platforms fills the gap between terrestrial and orbital monitoring stations, enabling researchers to target and conduct measurements in specific atmospheric regions. HALO enhances this capacity with its high altitude performance, generous payload of 3 tonnes and state-of-the-art measurement instruments.

The concept for this type of airborne atmospheric research was developed by representatives of leading German research institutions in the year 2000. Five years later, the DLR commissioned the construction of the HALO aircraft, which is based on the UltraLong Range Busi-ness Jet G 550. Following a call for proposals in 2006, the DFG commenced funding for the preparation of future missions the following year. On its completion in 2009, HALO began operations in 2010, undertaking measurements in a series of research flights dubbed the "Techno Mission". In June 2012, the aircraft undertook its first flight for the project "Geophysical Research of the Mediterranean using the HALO Research Aircraft" (GEOHALO). The project aims to improve our understanding of plate tectonics and the mechanisms under-lying earthquakes. GEOHALO is the first project in a geodetic and geophysical sequence of flights using HALO, effectively making it a pilot for subsequent projects, such as a planned mission over Antarctica.

Scientists hope to implement more than ten further projects in the period through to 2015, including the "Transport and Composition in the Upper Troposphere/Lowermost Stratosphere" (TACTS) mission, coordinated by the Goethe University in Frankfurt am Main within the framework of the DFG Priority Programme. This mission will study the chemical composition of the tropopause, an atmospheric region where the air masses of the troposphere and stratosphere meet. These two atmospheric layers feature different chemical compositions and their transport processes impact on changes in the climate.