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Title: Using Space‐Based CO 2 and NO 2 Observations to Estimate Urban CO 2 Emissions

As the majority of fossil fuel carbon dioxide (CO2) emissions originate from cities, the use of novel techniques to leverage available satellite observations of CO2and proxy species to constrain urban CO2is of great importance. In this study, we seek to empirically determine relationships between satellite observations of CO2and the proxy species nitrogen dioxide (NO2), applying these relationships to NO2fields to generate NO2‐derived CO2fields (NDCFs) from which CO2emissions can be estimated. We first establish this method using simulations of CO2and NO2for the cities of Buenos Aires, Melbourne, and Mexico City, finding that the method is viable throughout the year. For the same three cities, we next calculate empirical relationships (slopes) between co‐located observations of NO2from the Tropospheric Monitoring Instrument and Snapshot Area Mode observations of CO2from Orbiting Carbon Observatory‐3. Applying varying combinations of slopes to generate NDCFs, we evaluate methodological uncertainties for each slope application method and use a simple mass balance method to estimate CO2emissions from NDCFs. We demonstrate monthly urban CO2emissions estimates that are comparable to emissions inventory estimates. We additionally prove the utility of our method by demonstrating how large uncertainties at a grid cell level (equivalent to ∼1–3 ppm) can be reduced substantially when aggregating emissions more » estimates from NDCFs generated from all NO2swaths (about 1%–6%). Rather than rely on prior knowledge of emission ratios, our method circumvents such assumptions and provides a valuable observational constraint on urban CO2emissions.

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Publication Date:
Journal Name:
Journal of Geophysical Research: Atmospheres
DOI PREFIX: 10.1029
Sponsoring Org:
National Science Foundation
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