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Toward consistency between trends in bottom-up CO_2 emissions and top-down atmospheric measurements in the Los Angeles megacity

Newman, Sally and Xu, Xiaomei and Gurney, Kevin R. and Hsu, Ying Kuang and Li, King Fai and Jiang, Xun and Keeling, Ralph and Feng, Sha and O'Keefe, Darragh and Patarasuk, Risa and Wong, Kam Weng and Rao, Preeti and Fischer, Marc L. and Yung, Yuk L. (2016) Toward consistency between trends in bottom-up CO_2 emissions and top-down atmospheric measurements in the Los Angeles megacity. Atmospheric Chemistry and Physics, 16 (6). pp. 3843-3863. ISSN 1680-7324. doi:10.5194/acp-16-3843-2016.

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Large urban emissions of greenhouse gases result in large atmospheric enhancements relative to background that are easily measured. Using CO_2 mole fractions and Δ^(14)C and δ^(13)C values of CO_2 in the Los Angeles megacity observed in inland Pasadena (2006–2013) and coastal Palos Verdes peninsula (autumn 2009–2013), we have determined time series for CO_2 contributions from fossil fuel combustion (C_(ff)) for both sites and broken those down into contributions from petroleum and/or gasoline and natural gas burning for Pasadena. We find a 10 % reduction in Pasadena C_(ff) during the Great Recession of 2008–2010, which is consistent with the bottom-up inventory determined by the California Air Resources Board. The isotopic variations and total atmospheric CO_2 from our observations are used to infer seasonality of natural gas and petroleum combustion. The trend of CO_2 contributions to the atmosphere from natural gas combustion is out of phase with the seasonal cycle of total natural gas combustion seasonal patterns in bottom-up inventories but is consistent with the seasonality of natural gas usage by the area's electricity generating power plants. For petroleum, the inferred seasonality of CO_2 contributions from burning petroleum is delayed by several months relative to usage indicated by statewide gasoline taxes. Using the high-resolution Hestia-LA data product to compare C_(ff) from parts of the basin sampled by winds at different times of year, we find that variations in observed fossil fuel CO_2 reflect seasonal variations in wind direction. The seasonality of the local CO_2 excess from fossil fuel combustion along the coast, on Palos Verdes peninsula, is higher in autumn and winter than spring and summer, almost completely out of phase with that from Pasadena, also because of the annual variations of winds in the region. Variations in fossil fuel CO_2 signals are consistent with sampling the bottom-up Hestia-LA fossil CO_2 emissions product for sub-city source regions in the LA megacity domain when wind directions are considered.

Item Type:Article
Related URLs:
URLURL TypeDescription
Newman, Sally0000-0003-0710-995X
Gurney, Kevin R.0000-0001-9218-7164
Li, King Fai0000-0003-0150-2910
Jiang, Xun0000-0001-8932-3807
Keeling, Ralph0000-0002-9749-2253
Feng, Sha0000-0002-2376-0868
Patarasuk, Risa0000-0002-3961-4662
Rao, Preeti0000-0002-5549-0583
Fischer, Marc L.0000-0001-7956-2361
Yung, Yuk L.0000-0002-4263-2562
Additional Information:© Author(s) 2016. This work is distributed under the Creative Commons Attribution 3.0 License. Received: 09 Sep 2015. Published in Atmos. Chem. Phys. Discuss.: 29 Oct 2015. Revised: 05 Mar 2016. Accepted: 07 Mar 2016. Published: 22 Mar 2016. This work would not have been possible without support from the W. M. Keck Carbon Cycle Facility at UCI. We specifically thank J. Southon for his help with sample analysis. We acknowledge funding from the Keck Institute for Space Studies, NASA Grant NNX13AC04G, and NASA Grant NNX13AK34G. We also acknowledge funding from the California Air Resources Board Contract #13-329. The statements and conclusions in this report are those of the Contract and not necessarily those of the California Air Resources Board. The mention of commercial products, their source, or their use in connection with materials reported herein is not to be construed as actual or implied endorsement of such products. The authors gratefully acknowledge the NOAA Air Resources Laboratory (ARL) for providing the HYSPLIT transport and dispersion model used in this publication. We thank N. C. Shu for hosting the site on the Palos Verdes peninsula.
Group:Keck Institute for Space Studies, Division of Geological and Planetary Sciences
Funding AgencyGrant Number
Keck Institute for Space Studies (KISS)UNSPECIFIED
California Air Resources Board13-329
Issue or Number:6
Record Number:CaltechAUTHORS:20160606-075449018
Persistent URL:
Official Citation:Newman, S., Xu, X., Gurney, K. R., Hsu, Y. K., Li, K. F., Jiang, X., Keeling, R., Feng, S., O'Keefe, D., Patarasuk, R., Wong, K. W., Rao, P., Fischer, M. L., and Yung, Y. L.: Toward consistency between trends in bottom-up CO2 emissions and top-down atmospheric measurements in the Los Angeles megacity, Atmos. Chem. Phys., 16, 3843-3863, doi:10.5194/acp-16-3843-2016, 2016.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:67671
Deposited By: Ruth Sustaita
Deposited On:06 Jun 2016 16:47
Last Modified:11 Nov 2021 03:52

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