1Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
2Environmental Energy Technologies Division, E. O. Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
3Department of Earth System Science, University of California, Irvine, CA 92697, USA
4Department of Earth and Atmospheric Sciences, University of Houston, Houston, Texas 77004, USA
5Earth Atmospheric Science, Jet Propulsion Laboratory, Pasadena, CA 91109, USA
6NOAA ESRL Global Monitoring Division, Boulder, CO 80305, USA
7NOAA ESRL Chemical Sciences Division, Boulder, CO 80305, USA
8School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
Received: 20 Jan 2012 – Discussion started: 22 Feb 2012
Abstract. Attributing observed CO2 variations to human or natural cause is critical to deducing and tracking emissions from observations. We have used in situ CO2, CO, and planetary boundary layer height (PBLH) measurements recorded during the CalNex-LA (CARB et al., 2008) ground campaign of 15 May–15 June 2010, in Pasadena, CA, to deduce the diurnally varying anthropogenic component of observed CO2 in the megacity of Los Angeles (LA). This affordable and simple technique, validated by carbon isotope observations and WRF-STILT (Weather Research and Forecasting model – Stochastic Time-Inverted Lagrangian Transport model) predictions, is shown to robustly attribute observed CO2 variation to anthropogenic or biogenic origin over the entire diurnal cycle. During CalNex-LA, local fossil fuel combustion contributed up to ~50% of the observed CO2 enhancement overnight, and ~100% of the enhancement near midday. This suggests that sufficiently accurate total column CO2 observations recorded near midday, such as those from the GOSAT or OCO-2 satellites, can potentially be used to track anthropogenic emissions from the LA megacity.
Revised: 18 Feb 2013 – Accepted: 29 Mar 2013 – Published: 26 Apr 2013
Newman, S., Jeong, S., Fischer, M. L., Xu, X., Haman, C. L., Lefer, B., Alvarez, S., Rappenglueck, B., Kort, E. A., Andrews, A. E., Peischl, J., Gurney, K. R., Miller, C. E., and Yung, Y. L.: Diurnal tracking of anthropogenic CO2 emissions in the Los Angeles basin megacity during spring 2010, Atmos. Chem. Phys., 13, 4359-4372, doi:10.5194/acp-13-4359-2013, 2013.