The GAW-CH Aerosol Monitoring Program at the Jungfraujoch

Aerosols are solid or liquid particles in suspension in the air, which size is comprised between some nanometers and some hundred of micrometers. Aerosols may influence the atmosphere in two important ways, through aerosol direct effects and aerosol indirect effects. The direct effect is the mechanism by which aerosols scatter and absorb radiation, thereby altering the radiative balance of the Earth-atmosphere system. The indirect effect is the mechanism by which aerosol modify the microphysical and hence the radiative properties, amount and lifetime of clouds. Despite the uncertainty, it is believed that in regions with high anthropogenic aerosol concentrations, aerosol forcing may be of the same magnitude, but opposite in sign to the effect of all greenhouse gases.

Aerosol monitoring:

The objective of the GAW programme is to determine the spatio-temporal distribution of aerosol properties related to climate forcing and air quality up to multi-decadal time scales. The aerosol programme measured by the Laboratory of Atmospheric Chemistry of the Paul Scherrer Institut (LAC/PSI) at the global GAW station of the Jungfraujoch (JFJ) is one of the most comprehensive worldwide.
Because of the station elevation, the JFJ is considered to be partly in the free troposphere (FT) and therefore suited to the measurement of the background aerosol. A seasonal cycle is detected for all aerosol measured parameters and is principally due to convective transport of the planetary boundary layer up to the JFJ during summer times.

Long-term trend:

The 10-year aerosol trend analysis (Collaud Coen et al., 2007) showed that an increase in aerosol parameters is found in autumn when the JFJ is mainly influenced by the FT. During summer when the PBL influence at the JFJ is the greatest, no significant trends were detected for any of the analyzed parameters.

Selected recent publications:

Collaud Coen, M., Weingartner, E., Furger, M., Nyeki, S., Prévôt, A.S.H., Steinbacher, M., and Baltensperger, U.: Aerosol climatology and planetary boundary influence at the Jungfraujoch analyzed by synoptic weather types, Atmos. Chem. Phys., 11, 5931-5944, 2011. http://www.atmos-chem-phys.net/11/5931/2011/acp-11-5931-2011.pdf

Collaud Coen, M., Weingartner, E., Apituley, A., Ceburnis, D., Fierz-Schmidhauser, R., Flentje, H., Henzing, J. S., Jennings, S. G., Moerman, M., Petzold, A. et others: Minimizing light absorption measurement artifacts of the Aethalometer: evaluation of five correction algorithms, Atmos. Meas. Tech., 3, 457-474, 2010. www.atmos-meas-tech.net/3/457/2010/amt-3-457-2010.pdf

Cozic, J., Verheggen, B., Weingartner, E., Crosier, J., Bower, K. N., Flynn, M., Coe, H., Henning, S., Steinbacher, M., Henne, S., Collaud Coen, M., Petzold, A., and Baltensperger, U.: Chemical composition of free tropospheric aerosol for PM1 and coarse mode at the high alpine site Jungfraujoch, Atmos. Chemis. Phys., Vol.8, pp. 407-423 SRef-ID: 1680-7324/acp/2008-8-407, 2008. www.atmos-chem-phys.net/8/407/2008/acp-8-407-2008.pdf

Collaud Coen, M. C., Weingartner, E., Nyeki, S., Cozic, J., Henning, S., Verheggen, B., Gehrig, R. et Baltensperger, U.: Long-term trend analysis of aerosol variables at the high-alpine site Jungfraujoch, J. Geophys. Res., 112(D13), D13213, 2007. dx.doi.org/10.1029/2006JD007995

Collaud Coen, M, Weingartner, E., Schaub, D., Hueglin, C., Corrigan, C., Henning, S., Schikowski, M., and Baltensperger, U.: Saharan dust events at the Jungfraujoch: Detection by wavelength dependence of the single scattering albedo and first climatology analysis, 4, 2465-2480, 2004. www.atmos-chem-phys.net/4/2465/2004/acp-4-2465-2004.pdf