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Expanding urban populations and the significant contribution of cities to global fossil-fuel CO₂ (CO₂ff) emissions emphasize the necessity of achieving independent and accurate quantifications of the emissions from urban area. In this paper, we assess the utility of total column dry air CO₂ mole fraction (XCO₂) data retrieved from NASA’s Orbiting Carbon Observatory 2 (OCO-2) observations to quantify CO₂ff emissions from cities.

Airborne measurements of methane emissions from oil and gas infrastructure were completed over two regions of Alberta, Canada. These top-down measurements were directly compared with region-specific bottom-up inventories that utilized current industry-reported flaring and venting volumes (reported data) and quantitative estimates of unreported venting and fugitive sources.

We employed an atmospheric transport model to attribute column‐averaged CO₂ mixing ratios (XCO₂) observed by Greenhouse gases Observing SATellite (GOSAT) to emissions due to large sources such as megacities and power plants. XCO₂ enhancements estimated from observations were compared to model simulations implemented at the spatial resolution of the satellite observation footprint (0.1° × 0.1°).

The Indianapolis Flux Experiment (INFLUX) aims at quantifying emissions of anthropogenic carbon using top-down methods and process-based information (Hestia) at very high resolution over the city of Indianapolis (IN). At present, 9 sensors measuring continuously atmospheric mixing ratios of GHG have been deployed, with additional flask samples of isotopic ratios, one eddy-flux site measuring the surface energy and CO₂ fluxes, frequent aircraft flight measurements of GHG, and a column-integrated surface based sensor (FTS-TCCON).

The Indianapolis Flux Experiment (INFLUX) aims to use a top-down inversion methodology to quantify sources of Greenhouse Gas (GHG) emissions over an urban domain with high spatial and temporal resolution. Analyzing the contribution of different source types or sectors is a fundamental step in order to achieve an accuracy level desired for such applications. To this end, the Weather Research and Forecasting model (WRF-ARW) was used along with a modified version of the GHG chemistry module for simulating the CO₂ mole fraction transport during September and October 2013.