Can We Detect Urban-Scale CO₂ Emission Changes Within Medium-Sized Cities?
-
1.
University of Utah
- 2. Utah Clean Energy, Salt Lake City, UT, USA
-
3.
California Institute of Technology
Abstract
The COVID-19 pandemic resulted in a widespread lockdown during the spring of 2020. Measurements collected on a light rail system in the Salt Lake Valley (SLV), combined with observations from the Utah Urban Carbon Dioxide Network observed a notable decrease in urban CO2 concentrations during the spring of 2020 relative to previous years. These decreases coincided with a ∼30% reduction in average traffic volume. CO2 measurements across the SLV were used within a Bayesian inverse model to spatially allocate anthropogenic emission reductions for the first COVID-19 lockdown. The inverse model was first used to constrain anthropogenic emissions for the previous year (2019) to provide the best possible estimate of emissions for 2020, before accounting for emission reductions observed during the COVID-19 lockdown. The posterior emissions for 2019 were then used as the prior emission estimate for the 2020 COVID-19 lockdown analysis. Results from the inverse analysis suggest that the SLV observed a 20% decrease in afternoon CO2 emissions from March to April 2020 (−90.5 tC hr−1). The largest reductions in CO2 emissions were centered over the northern part of the valley (downtown Salt Lake City), near major roadways, and potentially at industrial point sources. These results demonstrate that CO2 monitoring networks can track reductions in CO2 emissions even in medium-sized cities like Salt Lake City.
Copyright and License
© 2023. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Acknowledgement
This study was funded by the NOAA Climate Program Office's Atmospheric Chemistry, Carbon Cycle, and Climate program (NA20OAR4310301 and NA21OAR4310232). The authors would also like to acknowledge support from the University of Utah's SEED2SOIL program. We would also like to thank the Utah Transit Authority and the Utah Department of Environmental Quality for supporting the measurements collected on the TRAX light rail train. Model simulations and analyses were carried out using computational resources provided by the University of Utah's Center for High Performance Computing. We would finally like to acknowledge Snowbird Ski Resort for hosting the Hidden Peak site used for background measurements of CO2.
Funding
This study was funded by the NOAA Climate Program Office's Atmospheric Chemistry, Carbon Cycle, and Climate program (NA20OAR4310301 and NA21OAR4310232). The authors would also like to acknowledge support from the University of Utah's SEED2SOIL program.
Contributions
Conceptualization: Derek V. Mallia.
Data curation: Derek V. Mallia, Logan E. Mitchell, Dien Wu.
Formal analysis: Derek V. Mallia, Dien Wu.
Funding acquisition: Derek V. Mallia, Logan E. Mitchell, John C. Lin.
Investigation: Derek V. Mallia, Lewis Kunik.
Methodology: Derek V. Mallia, Lewis Kunik.
Project Administration: Derek V. Mallia, Logan E. Mitchell, John C. Lin.
Resources: Derek V. Mallia.
Data Availability
Biospheric fluxes for northern Utah were estimated using the SMUrF data set, which is publicly available at the Oak Ridge National Lab data base (Wu, 2021). Anthropogenic emissions for the northern Utah were obtained from the Vulcan emission inventory, which is downloadable from the Oak Ridge National Lab database (Gurney et al., 2019). The HYSPLIT-STILT v5.0.0 software was used to generate the spatiotemporal influence matrix for each measurement (NOAA ARL, 2020). Meteorological data used to drive HYSPLIT-STILT backward trajectories were generated by output from the Weather Research and Forecast model v4.2 software available at NCAR: https://www2.mmm.ucar.edu/wrf/users/download/get_source.html (Skamarock et al., 2019). Utah traffic data for 2019 and 2020 is publicly available on the Utah Department of Transportation's webpage (UDOT, 2023). TRAX and UUCON CO2 data is hosted by the University of Utah and is publicly available at https://air.utah.edu (Lin et al., 2018).
Files
| Name | Size | Download all |
|---|---|---|
|
md5:ee005b40cd62137bfd4bd7a44bd2336a
|
5.2 MB | Preview Download |
|
md5:85c27ffc1f2a8124f3794b7aabc1c4ad
|
153.4 kB | Download |
Additional details
- National Oceanic and Atmospheric Administration
- NA20OAR4310301
- National Oceanic and Atmospheric Administration
- NA21OAR4310232
- University of Utah
- SEED2SOIL
- Available
-
2023-06-10Issue Online
- Accepted
-
2023-05-14Manuscript Accepted
- Caltech groups
- Division of Geological and Planetary Sciences
- Publication Status
- Published