Abstract
In this work, column-averaged dry-air mole fractions of carbon dioxide (XCO2), methane (XCH4) and carbon monoxide (XCO) are presented for the first time at a mid-latitude urban station, Thessaloniki, Greece, using the Bruker EM27/SUN ground-based low-resolution Fourier Transform spectrometer operated according to the requirements of the Collaborative Carbon Column Observing Network (COCCON). Two years of measurements are presented and examined for seasonal variability. The observed XCO2 levels show the expected seasonal cycle (spring maximum, late summer minimum) with a peak-to-peak amplitude of 12 ppm, with maximum values reported for winter 2021 exceeding 416 ppm. The XCH4 values are shown to increase in the second half of the year, with autumn showing the highest mean value of 1.878 ± 0.01 ppm. The XCO levels, following anthropogenic sources, show high winter and low summer values, exhibiting a rise again in August and September with a maximum value of 114 ± 3 ppb and a minimum in summer 2020 of 76 ± 3 ppb. Additionally, methane and carbon monoxide products obtained from the TROPOspheric Monitoring Instrument (TROPOMI), Sentinel-5P space borne sensor, are compared with the ground-based measurements. We report a good agreement between products. The relative mean bias for methane and carbon monoxide are −0.073 ± 0.647% and 3.064 ± 5.566%, respectively. Furthermore, a 15-day running average is subtracted from the original daily mean values to provide ΔXCO2, ΔXCO and ΔXCH4 residuals, so as to identify local sources at a synoptic scale. ΔXCO and ΔXCO2 show the best correlation in the winter (R2 = 0.898, slope = 0.007) season due to anthropogenic emissions in this period of the year (combustion of fossil fuels or industrial activities), while in summer no correlation is found. ΔXCO and ΔXCH4 variations are similar through both years of measurements and have a very good correlation in all seasons including winter (R2 = 0.804, slope = 1.209). The investigation of the X-gases comparison is of primary importance in order to identify local sources and quantify the impact of these trace gases to the deregulation of earth-climate system balance.
Highlights
Industrialisation, urbanisation, transport and domestic heating sustain but continuously increase the need for fossil fuel combustion, the main source of the anthropogenic component of the carbon cycle
The amplitude of the seasonal cycle in CO2 is larger in the northern hemisphere than in the southern hemisphere, as northern hemispheric continents are the areas containing the majority of land plants covering the Earth’s surface and the seasonal changes in temperature result in large differences in plant photosynthesis from summer to winter
Compared to other mid-latitude NDACC Fourier transform infrared (FTIR) stations, such as those in Bremen, Garmisch and Karlsruhe, Germany, we find a good agreement with our Collaborative Carbon Column Observing Network (COCCON) site in Thessaloniki
Summary
Industrialisation, urbanisation, transport and domestic heating sustain but continuously increase the need for fossil fuel combustion, the main source of the anthropogenic component of the carbon cycle. Agriculture, coal mining, waste management, natural gas networks and other human activities greatly contribute to the increase of greenhouse gas (GHG) concentrations in the atmosphere. 2021, 13, 3395 of atmospheric greenhouse gas abundances is the major driver of anthropogenic global warming and subsequently climate change. The most important longlived greenhouse gas in the atmosphere, is responsible for about 65% of the radiative forcing (RF) and continues to increase at a rate approximately 2.0 ± 0.1 ppm per year for. Methane (CH4 ), the second most important anthropogenic greenhouse gas after CO2 , has increased by about 259%.
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