Multiscale observations of CO₂, ¹³CO₂, and pollutants at Four Corners for emission verification and attribution

Abstract

There is a pressing need to verify air pollutant and greenhouse gasemissions from anthropogenic fossil energy sources to enforcecurrent and future regulations. We demonstrate the feasibility ofusing simultaneous remote sensing observations of column abun-dances of CO₂, CO, and NO2to inform and verify emission inven-tories. We report, to our knowledge, the first ever simultaneouscolumn enhancements in CO₂(3–10 ppm) and NO2(1–3 DobsonUnits), and evidence ofδ¹³CO₂ depletion in an urban region withtwo large coal-fired power plants with distinct scrubbing technol-ogies that have resulted inΔNOx/ΔCO₂emission ratios that differby a factor of two. Ground-based total atmospheric column tracegas abundances change synchronously and correlate well with simultaneous in situ point measurements during plume intercep-tions. Emission ratios of ΔNOx /ΔCO₂andΔSO2/ΔCO₂ derived from in situ atmospheric observations agree with those reported by in-stack monitors. Forward simulations using in-stack emissions agree with remote column CO₂and NO₂ plume observations after fine scale adjustments. Both observed and simulated column ΔNO₂/ΔCO₂ ratios indicate that a large fraction (70–75%) of theregion is polluted. We demonstrate that the column emission ra-tios of ΔNO₂/ΔCO₂ can resolve changes from day-to-day variation in sources with distinct emission factors (clean and dirty power plants, urban, and fires). We apportion these sources by usingNO₂ ,SO₂, and CO as signatures. Our high-frequency remote sens-ing observations of CO₂ and co emitted pollutants offer promise for the verification of power plant emission factors and abatement technologies from ground and space.