Partitioning of biogenic and anthropogenic CO2 signals using CO Tracer Technique

  • Lahiru Gamage
  • Ha Nguyen


The poster reports a CO:CO2 ratio technique in the estimation and quantification of biogenic CO2 (CO2 bio) and anthropogenic CO2 (CO2 anth) signals in an urban setting following continuous dry mixing ratio measurements of carbon dioxide (CO2) and carbon monoxide (CO) using a wavelength-scanned cavity Ring-Down spectroscopic (CRDS) technology. The measurements were carried out in different days during the spring, summer, and winter of 2017 and 2018 at a height 15 m above the ground. The CO:CO2 correlation ratios (β values) were evaluated using regression analysis after subtracting the region’s background concentration based on a 5th percentile background subtraction technique. For the year 2017, β values (ppb:ppm-1) of 9.7 ± 0.4, 5.3 ± 0.4, and 2.0 ± 0.2 were obtained for the winter, spring and summer seasons, respectively. In 2018, a similar trend in the β values was observed where values of 8.7 ± 0.5, 7.4 ± 0.7, and 2.6 ± 0.5 measured in winter, spring, and summer seasons, respectively. Correlation values (r2) of 0.9, 0.8 and 0.6 were obtained for winter, spring and summer seasons respectively, indicating the strong biospheric CO2 exchange during summertime. This strong biospheric signal is brought about by the strong photosynthetic activity in the summertime as opposed to the dominant respiratory carbon fluxes that dominate the winter season.