Back to overview

A century of apparent atmospheric transmission over Davos, Switzerland

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Lachat D., Wehrli C.,
Project Global Change and Mountain Regions: the Mountain Research Initiative Coordination Office
Show all

Original article (peer-reviewed)

Journal Theoretical and Applied Climatology
Title of proceedings Theoretical and Applied Climatology
DOI 10.1007/s00704-012-0685-z


Pyrheliometer measurements have been carried out at the Physikalisches-Meteorologisches Observatorium Davos from 1909 to present which results in the longest stationary direct irradiance record worldwide. A variety of different instruments and measurement scales were homogenized and adjusted to the World Radiometric Reference. Following the pyrheliometric ratioing technique, a time–series of apparent atmospheric transmission was calculated and analyzed for possible trends in column transparency over Davos. In order to assess the trend found in the transmission record, the long-term annual cycle in apparent atmospheric transmission was used to deseasonalize the daily transmission data. The trends of early brightening, dimming and brightening were localized and found to be small but highly significant.