High resolution solar FTIR spectrometer

The solar high-resolution Bruker 120M infra-red FT spectrometer (mobile version of the 125HR model) is a core element of our initial observation platform. This extremely versatile instruments provides both integrated total column amounts of some 35 atmospheric molecular constituents as well their respective vertical distributions (with modest vertical resolution) and their isotopic ratios. Continuous and ongoing measurement programmes exist since about 1985, which were formalised in the global measurement network NDACC and its predecessor NDSC in 1991.

We aim to establish ongoing atmospheric composition measurements within the global observation network NDACC and the COCCON project in support of GCOS, Copernicus and ACTRIS and the validation of international environmental satellites.

Bruker 120M FTIR spectrometer on Spitsbergen with covers removed.

Network for the Detection of Atmospheric Change (NDACC)

Present TRS staff has been active in the NDACC since 1993, then operating the FTIR spectrometer at Ny Ålesund, Spitsbergen (78.925N, 11.922E).

Ny Ålesund, Spitsbergen, 78.925N, 11.922E (photo by Arndt Meier, 1994)

Sun tracker of the FTIR spectrometer tracking the low Arctic sun.

It is thanks to an earlier version of this instrument and in particular one person that the Montreal protocol banned the use of freons leading to the recovery of the ozone layer, my esteemed colleague the late Rodolphe ‘Rudy’ Zander operating his instruments on the Jungfraujoch since 1950, where he could demonstrate that no freons had been present then and that thus freons were entirely man-made. Similar arguments hold for Rudy’s observations of greenhouse gases like methane, carbon dioxide, nitrous oxide and sulfur hexafluoride with respect to the Kyoto protocol. It is one of the strongest arguments for long-term high-quality observations of the atmospheric state.

The Bruker 120M FTS has been kindly provided by the University of Heidelberg (André Butz) and is presently undergoing refurbishment for infra-red operation and maintenance service at Bruker Optics, Germany. It will be the third such instrument operated in South America besides the spectrometers in Paramaribo/Surinam, and Porto Vellio/Brasil operated by NDACC groups in Germany and Belgium, respectively.