High spatiotemporal resolution urban fossil fuel CO ₂ emissions mapping and modeling: A pilot study in Indianapolis, Indiana, USA

In order to advance the scientific understanding of terrestrial carbon exchange and contribute to quantitatively-based climate change mitigation at the national to urban scales, quantification of greenhouse gases emissions drivers at fine spatial and temporal scales is essential. Quantification of sector-specific fossil fuel CO ₂ emissions, the primary greenhouse gases, has become a key component to cost-effective CO ₂ emissions mitigation options and a carbon trading system. Being the 12 ^th largest city in the United States with significant seasonality, Indianapolis serves as a good test case for high resolution CO ₂ emissions quantification and modeling. Called the 'Hestia Project', this pilot study generates CO ₂ emissions every hour at the scale of individual buildings and road segments in Indianapolis. The urban scale effort begins with county level estimation produced by the Vulcan Project, which quantifies fossil fuel CO ₂ emissions at coarser scales across the entire U.S. A combination of geocoded point source information and county-level estimates are downscaled and further improved through the use of air quality and traffic monitoring data, remote sensing, GIS, geospatial statistics, and building energy modeling. For example, we utilize observed hourly CO ₂ emissions available at electrical generating units for powerplant facilities. We quantify the commercial and residential emissions using Assessor's parcel data, building footprints GIS data, and remote sensing data to determine building height. Mobile source CO ₂ emissions are estimated at the month/county scale using the Mobile6 combustion model and the National Mobile Inventory Model database and downscaled to road segments, every hour using a GIS road atlas and ATR traffic data. These urban scale methods, results and analysis should be of use to city environmental managers and industry, offering a means to baseline emissions, plan mitigation strategies, and atmospheric sampling/evaluation strategies. This effort can also test remote sensing capabilities aimed at atmospheric CO ₂ and carbon flux measurements.