Whoever wants a glimpse of the future of our climate has to cast his eyes upward. Almost into outer space, up some 100 kilometres, at night. Then the consequences of global warming become rapidly evident. For years the Earth Observation Center (EOC) has been monitoring the temperature of the atmosphere at this altitude and analysing the changes—in order to improve climate models and to detect natural disasters early, like flooding, earthquakes and tsunami. The "base camp" for measurements is Germany‘s highest research station, the Schneefernerhaus Environmental Research Station (UFS) on Zugspitze mountain.
With this year’s UN Climate Conference in Paris in mind, the Federal Minister of the Environment, Nature Conservation, Building and Nuclear Safety, Barbara Hendricks, paid a visit to Schneefernerhaus on 6 July 2015. She informed herself about the latest developments in climate and environmental research. She was joined by Ulrike Scharf, Bavarian State Minister of Environment and Consumer Protection and Markus Reiterer, General Secretary of the Alpine Convention.
"Climate change leaves traces in almost all realms of System Earth. At the Schneefernerhaus Environmental Research Station a number of science institutions share tasks to detect these traces and monitor the effects of climate change at all levels, from the ground to the upper atmosphere. That is our contribution to international climate research activities" was how Prof. Michael Bittner of DLR’s German Remote Sensing Data Center and the spokesman of the UFS science team described the challenge.
The temperature of the atmosphere as early indicator
Earth’s surface takes ten years to increase in temperature by one half degree Celsius. Measurements which can reliably document that rate of increase are difficult to achieve. In the upper levels of the atmosphere the changes are much more evident. In the course of ten years, warming at the surface leads to cooling of up to five or even ten degrees Celsius in the mesosphere—a layer of the atmosphere found at altitudes between 50 and 80 kilometres. Changes in the climate and their effects can therefore be reliably identified more rapidly. At the research station’s DLR laboratory Germany’s minister of the environment familiarized herself with the technology being employed.
Bittner and his team operate an exceptional "atmosphere thermometer" on Zugspitze mountain: the GRIPS infrared spectrometer (Ground-based Infrared P-branch Spectrometer) and an imaging infrared camera trigger measurements at minute intervals, night for night. Atmospheric illumination at the edge of outer space, so-called "airglow", emits characteristic infrared radiation. Scientists can read this radiation like a fingerprint. Excited hydroxyl molecules (OH) produce a signature that permits conclusions about the temperature prevailing there.
The high-alpine location of Schneefernerhaus facilitates precise measurements without light pollution from streetlights or other types of artificial illumination. Worldwide, GRIPS measurements are made at a total of eleven locations, from Tel Aviv in Israel to the Neumeyer research station in the Antarctic.
Faster detection of natural hazards
GRIPS data are used not only for climate monitoring but also to quickly detect natural hazards. This application also aroused the interest of Environmental Minister Hendricks. The latest DLR research shows that tsunami and earthquakes generate infrasound, in each case with a characteristic temperature signature.
The sound from such events ascends into the atmosphere and spreads out like a pressure wave. Air is compressed and expanded, and with each meter of altitude the air density decreases exponentially. These phenomena modify the temperature fluctuation of the atmosphere, and at an altitude around 100 kilometres this fluctuation can be considerable. The DLR scientists have found out, for example, that tsunami cause the airglow of the mesopause to "flicker".
Temperature disturbances of a mere tenth of a degree at the surface of the ocean lead to fluctuations in the upper mesosphere of some ten degrees, a disturbance that can easily be confirmed by GRIPS. Measurements with the customized infrared spectrometer should also contribute to improving meteorological forecast models. For example, heavy rainstorms that may cause flooding can already be reliably forecast two to three weeks in advance, instead of today’s three to five-day prognosis.
Using GRIPS to investigate earthquake and volcanic activity is an innovative approach. For some time, GRIPS measurements have therefore been collected on Mount Etna in Italy and in the Georgian Caucasus for that purpose. But this by no means exhausts the list of promising research topics and possible applications. Bittner adds, "We want to carry out measurements also from space in the future. So we are continuing to develop the GRIPS system at Schneefernerhaus Environmental Research Station for installation on satellites." Then the future development of the climate will also become visible from above for researchers of the atmosphere.
About the research station
The Schneefernerhaus Environmental Research Station (UFS) is the "virtual institute" of a science consortium under the aegis of the Bavarian Ministry of the Environment and Consumer Protection. The ten consortium partners are the German Aerospace Center (DLR), Germany's national meteorological service Deutsche Wetterdienst (DWD), Helmholtz Zentrum München (HMGU), Karlsruhe Institute of Technology (KIT), Ludwig-Maximilians-Universität München (LMU), Max Planck Society Munich (MPG), Technische Universität München (TUM), Augsburg University (UAU), Umweltbundesamt (UBA) and the Free State of Bavaria. The infrastructure of the alpine research station is managed by the operating company UFS GmbH.