Measurement of climate-relevant trace gases via infrared spectroscopy
The goal of this thesis was to develop and build a fully automated FTIR system for total column measurements of atmospheric trace gases. As part of TCCON, it is planned to install the system in the tropics where such measurements are very sparse. The designated site is Ascension Island, a British oversea territory in the South Atlantic. This unique location should provide excellent observation conditions for the FTIR instrument. Due to its small size and very scarce vegetation, the inﬂuence from local sources and sinks on the CO2 and CH4 measurements should be minimal. This work describes the history of the system in three parts: Development, Calibration, and Testing. Chapter 2 introduces the design of the system: chosen components and self- made parts like a custom solar tracker protection dome are explained and the automation concept of the system is illustrated. Besides that, ﬁrst results of total column measurements in Jena are presented. In 2009, after the Jena FTIR system was completed, it took part in the IMECC aircraft calibration campaign. The integration of the FTIR measurements into the existing ground-based in-situ network requires a calibration. Earlier campaigns (Wunch et al., 2010) pointed out that it is highly likely that there is a species-speciﬁc uniform calibration factor for all TCCON FTIR systems. The goal of the IMECC aircraft campaign was to verify these ﬁndings and to calibrate six of the European TCCON stations. The results of the CH4 calibration are presented in Chapter 3. After successfully taking part in the calibration campaign, the FTIR system was shipped to Australia for a test campaign. The aim was to prove the systems functionality and to compare the measurements of the system to the ones performed by a similar instrument operated by the University of Wollongong (UoW), Australia. The results of this campaign are presented in Chapter 4.