Simultaneous atmospheric observation of CO2 flux, 14CO2, O2 and CO2 concentrations and aerosol components in Tokyo for partitioning of CO2 flux into emission sources

Variations in carbon dioxide (CO₂) flux observed in urban area are considered to be attributed to the CO₂ emissions from burning of fossil fuels (oil, natural gas, and coal) and from biotic activities. To evaluate CO₂ flux from each emission source, we have simultaneously observed CO₂ flux, atmospheric radiocarbon in CO₂ (¹⁴CO₂), atmospheric oxygen (O₂), CO₂, methane (CH₄) and carbon monoxide (CO) concentrations and aerosol components at the Yoyogi (YYG) site (35.66 N, 139.68 E), Shibuya, Tokyo. At YYG site, CO₂ fluxes were continuously measured at 52m above ground (25m above roof), CO₂ and O₂ concentrations were continuously measured at 52m and 37m, ¹⁴CO₂ were measured by flask samplings of the air at 52m, aerosol components were continuously measured at 27m (on the roof), and CO₂, CH₄, and CO concentrations were continuously measured at 37m. The ¹⁴CO₂ measurement is used for separating the fossil fuel CO₂ emissions from the biotic emissions. Preliminary results from ¹⁴CO₂ measurement indicated that a ratio of fossil fuel-derived CO₂ to the variation of CO₂ concentrations varied from 50% to 100%. The O₂:CO₂ exchange ratio (oxidation ratio) provides information on the fuel types (oil or natural gas). The aerosol component measurement is used for detecting coal burnings. In this presentation, we show our observational data and preliminary results of the partitioning of CO₂ flux into emission sources using ¹⁴CO₂ and O₂.