Wunch, D. and Wennberg, P. O. and Toon, G. C. and Keppel-Aleks, G. and Yavin, Y. G. (2009) Emissions of greenhouse gases from a North American megacity. Geophysical Research Letters, 36 (15). L15810. ISSN 0094-8276 http://resolver.caltech.edu/CaltechAUTHORS:20090826-112853465
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Atmospheric column abundances of carbon dioxide (CO_2), carbon monoxide (CO), methane (CH_4) and nitrous oxide (N_2O) have been measured above the South Coast air basin (SCB), a densely populated urban region of Southern California, USA, which includes Los Angeles and the surrounding suburbs. Large diurnal variations in CO and CH_4 are observed which correlate well with those in CO_2. Weaker correlations are seen between N_2O and CO_2, with large uncertainties. We compute yearly SCB emissions of CO and CH_4 to be 1.4 ± 0.3 Tg CO and 0.6 ± 0.1 Tg CH_4. We compare our calculated emissions to the California Air Resources Board (CARB) and the Emission Database for Global Atmospheric Research (EDGAR) estimates. Our measurements confirm that urban emissions are a significant source of CH_4 and in fact may be substantially higher than currently estimated. If our emissions are typical of other urban centers, these findings suggest that urban emissions could contribute 7–15% to the global anthropogenic budget of methane.
|Additional Information:||©2009. American Geophysical Union. Received 29 June 2009; accepted 9 July 2009; published 6 August 2009. The authors thank Alan Kwan, Kathleen Spencer, Amy Townsend-Small, Charles E. Miller and Ying K. Hsu for helpful discussions, Jean-François L. Blavier for invaluable technical assistance and two anonymous reviewers for insightful comments. The authors gratefully acknowledge the NOAA Air Resources Laboratory (ARL) for the provision of the READY website (http://www.arl.noaa.gov/ready.html) used in this publication [Draxler and Rolph, 2003; Rolph, 2003]. Part of this research was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Support for this work is from the NASA Carbon Cycle Program grant NNX08AI86G and from the NASA OCO Project grant NAS7-03001.|
|Subject Keywords:||greenhouse gas; urban; methane|
|Official Citation:||Wunch, D., P. O. Wennberg, G. C. Toon, G. Keppel-Aleks, and Y. G. Yavin (2009), Emissions of greenhouse gases from a North American megacity, Geophys. Res. Lett., 36, L15810, doi:10.1029/2009GL039825.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||George Porter|
|Deposited On:||11 Sep 2009 18:56|
|Last Modified:||26 Dec 2012 11:15|
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