Completed projects


The Medusa is an analytical system (preconcentration unit and GC/MS) for the detection of  more than 40 halogenated ozone-depleting gases and greenhouse gases. The Medusa was developed at the Scripps Institution of Oceanography for the AGAGE (Advanced Global Atmospheric Gases Experiment) programme. At the heart of the preconcentration unit are two traps which are cooled to -165°C (liquid N2 free). The design of these traps allow accurate measurements even at very low concentrations (ppt) as well as the detection of several new substances (e.g. tetrafluoromethane). The Medusa system at Jungfraujoch station has been delivering 2-hourly air measurements since it’s installation in spring 2008. We have completed building 5 new Medusa systems at our laboratory in Dübendorf in cooperation with our colleagues at NILU (Norwegian Institute for Air Research) and CAMS (Chinese Academy of Meteorological Sciences). These Medusas are now installed at the GAW station of Shangdianzi (China), in the laboratory at CAMS, at the Zeppelin station in Spitsbergen, in the NILU laboratory in Kjeller, and at the Empa laboratory. Measurements at the two fields stations are ongoing and results are included in the AGAGE network.




The LEMURE project (PhD of Christoph Keller) will advance methods to obtain reliable and independent emission numbers of non-CO2 greenhouse gases, which can be used to check emissions to be reported by the signatory countries within the Kyoto Protocol.

The common way to calculate the emissions of such species is a bottom-up approach, where categories of usage and specific activity functions are applied. Within the LEMURE project, an alternative method of estimating the emissions of non-COgreenhouse gases will be applied. This method is based on continuous ground-based measurements of these gases at Jungfraujoch (SOGE/HALCLIM) (Switzerland) and K-puszta (Hungary), in combination with measurements of Radon (222Rn) and meteorological transport models222Rn is an excellent reference tracer for continental air masses, since it has a well-known half-life of 3.8 days and spatial as well as temporal relatively homogeneous emission rates (see for further details).


Oxygenated Volatile Organic Compounds

OVOCs (oxygenated volatile organic compounds) are an important fraction of the organic air pollutants. OVOCs encompass important anthropogenically emitted substances such as alcohols, ketones, ethers and esters. OVOCs have been measured by a specifically developed adsorption unit and GC-MS in 3 different campaigns:

1. Gubrist-tunnel (2003) aim: emissions of OVOCs from traffic
For details see: Legreid et al. (2007): Measurements of OVOCs and NMHCs in a Swiss Highway Tunnel for Estimation of Road Transport Emissions

2. Zürich city (2005/06) aim: assessment of anthropogenig emissions
For details see: [pdf], Oxygenated volatile organic compounds (OVOCs) at an urban background site in Zürich (Europe): Seasonal variation and source allocation

3. Jungfraujoch high-Alpine (2005/06) aim: background climatology and European sources
For details see: Legreid et al. (2008), Measurements of organic trace gases including oxygenated volatileorganic compounds at the high alpine site Jungfraujoch (Switzerland): Seasonal variation and source allocations.


Sources and Sinks of Hydrogen in the Atmosphere during Transition to Hydrogen-based Transportation (SASHA-THT)

The PhD thesis “Sources and Sinks of Hydrogen in the Atmosphere during Transition to Hydrogen-based Transportation” commenced in the summer of 2007. The thesis is part of the Competence Center for Energy and Mobility (CCEM-CH) project “Transition to hydrogen-based transportation (Hy_Change)” led by Professor Alexander Wokaun. Details of Hy_Change can be found at

Monitoring Atmospheric Hydrogen

H2 observations from Jungfraujoch are currently being analyzed and interpreted for the more than 2-year period of 08.2005 – 10.2007. The goal of these observations is to evaluate various trends (e.g. diurnal, seasonal, annual), in addition to identifying European sources. Continuous H2 (and carbon monoxide (CO)) measurements are conducted at Jungfraujoch with a modified reduction gas analyzer (RGA-3).

Sources of Atmospheric Hydrogen

Currently, at the chassis dynamometer test stand within Empa’s Laboratory for Internal Combustion Engines, direct online H2 emissions from vehicles are measured using a mass spectrometer based on the electron pulse ionization (EIMS) principle. The emissions, which are measured from vehicles selected from the Swiss fleet (current technologies such as gasoline and diesel fuels), result from vehicles driving pre-designed test cycles. These cycles are aimed at simulating real-world driving conditions – from urban, to rural, to highway conditions. Figures 3 and 4 below depict results of measurements from a diesel Euro-4 automobile and a gasoline Euro-3 motorcycle.