Analyzing Four Years of Ground-Based Measurements of XCO₂ and XCO over Thessaloniki, Greece Using FTIR Spectroscopy

Abstract

The issue of atmospheric pollution in urban centers has become a growing concern in recent years. The increasing levels of greenhouse gases in the atmosphere are a major contributor to atmospheric pollution, and it is imperative to monitor these gases. This study presents the measurements of column-averaged dry-air mole fractions of carbon dioxide (XCO2) and carbon monoxide (XCO) in Thessaloniki, Greece. The measurements were taken in Thessaloniki using the Bruker EM27/SUN instrument, which was developed by Bruker and KIT and has been part of the Collaborative Carbon Column Observing Network (COCCON) since 2018. COCCON is a global network of stations around the globe and serves as an important supplement to the high-resolution Bruker IFS125 spectrometer used in the Total Carbon Column Observing Network (TCCON), and it provides an increased density of column-averaged greenhouse gas observations. In this work, a four-year analysis of column-averaged dry-air mole fractions of XCO2 and XCO is presented, focusing on diurnal and seasonal cycles as well as on the comparison between them. The hourly time series show the expected seasonal cycle of XCO2 with a spring maximum and late summer minimum due to photosynthesis activity, while XCO2 presents a daily maximum of 419.987 ± 2.286 ppm and a daily minimum of 405.001 ± 3.067 ppm. The seasonal co-variability between XCO2 and XCO reveals an interesting correlation—especially during winter (R2=0.841 for 2022) and spring (R2=0.437 for 2022) period, when anthropogenic emission sources occur.

Keywords

• FTIR
• EM27/SUN
• COCCON
• Thessaloniki
• XCO₂
• XCO