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Differential column measurements using compact solar-tracking spectrometers

Chen, Jia and Viatte, Camille and Hedelius, Jacob K. and Jones, Taylor and Franklin, Jonathan E. and Parker, Harrison and Gottlieb, Elaine W. and Wennberg, Paul O. and Dubey, Manvendra K. and Wofsy, Steven C. (2016) Differential column measurements using compact solar-tracking spectrometers. Atmospheric Chemistry and Physics, 16 (13). pp. 8479-8498. ISSN 1680-7324. doi:10.5194/acp-16-8479-2016.

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We demonstrate the use of compact solar-tracking Fourier transform spectrometers (Bruker EM27/SUN) for differential measurements of the column-averaged dry-air mole fractions of CH_4 and CO_2 within urban areas. Using Allan variance analysis, we show that the differential column measurement has a precision of 0.01 % for X_(CO_2) and X_(CH_4) with an optimum integration time of 10 min, corresponding to Allan deviations of 0.04 ppm and 0.2 ppb,respectively. The sensor system is very stable over time and after relocation across the continent. We report tests of the differential column measurement,and its sensitivity to emission sources, by measuring the downwind-minus-upwind column difference ΔX_(CH_4) across dairy farms in the Chino area, California, and using the data to verify emissions reported in the literature. Ratios of spatial column differences ΔX_(CH_4)∕ΔX_(CO_2) were observed across Pasadena within the Los Angeles basin, indicating values consistent with regional emission ratios from the literature. Our precise, rapid measurements allow us to determine significant short-term variations (5–10 min) of X_(CO_2) and X_(CH_4) and to show that they represent atmospheric phenomena. Overall, this study helps establish a range of new applicationsfor compact solar-viewing Fourier transform spectrometers. Byaccurately measuring the small differences in integrated column amounts acrosslocal and regional sources, we directly observe the mass loadingof the atmosphere due to the influence of emissions in theintervening locale. The inference of the source strength is muchmore direct than inversion modeling using only surface concentrationsand less subject to errors associated with small-scale transportphenomena.

Item Type:Article
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URLURL TypeDescription
Hedelius, Jacob K.0000-0003-2025-7519
Jones, Taylor0000-0001-5860-3419
Wennberg, Paul O.0000-0002-6126-3854
Wofsy, Steven C.0000-0002-3990-6737
Additional Information:© Author(s) 2016. This work is distributed under the Creative Commons Attribution 3.0 License. Received: 29 Dec 2015 – Published in Atmos. Chem. Phys. Discuss.: 17 Feb 2016. Revised: 06 Jun 2016 – Accepted: 08 Jun 2016 – Published: 12 Jul 2016. We thank Bruce Daube and John Budney for the preparation of the measurement campaign in Chino and Pasadena and for building the weather stations and the enclosures for the spectrometers. We thank Frank Hase for help with the PROFFIT retrieval software, Matthias Frey for instructions on the ILS measurements, and Matthäus Kiel for the Calpy software. We thank Yanina Barrera for the lidar data and Frank Hase, Kelly Chance, Christoph Gerbig, Bruce Daube, John Budney, Bill Munger, Rachel Chang, and Kathryn McKain for fruitful discussions. Funding for this study was provided by the National Science Foundation through Major Research Instrumentation Award 1337512 “Acquisition of Mesoscale Network of Surface Sensors and Solar-tracking Spectrometers”. Jia Chen was partly supported by Technische Universität München – Institute for Advanced Study, funded by the German Excellence Initiative and the European Union Seventh Framework Programme under grant agreement no. 291763. Harrison Parker and Manvendra K. Dubey (Los Alamos National Laboratory) acknowledge NASA’s Carbon Monitoring Program for funding the EM27/SUN application development. The authors gratefully acknowledge the NOAA Air Resources Laboratory (ARL) for the provision of the HYSPLIT transport and dispersion model. The authors would also like to thank the anonymous reviewers for helpful comments. This work was supported by the German Research Foundation (DFG) and the Technische Universität München within the funding programme Open Access Publishing. Edited by: M. Heimann
Funding AgencyGrant Number
Technische Universität MünchenUNSPECIFIED
European Research Council (ERC)291763
Deutsche Forschungsgemeinschaft (DFG)UNSPECIFIED
Issue or Number:13
Record Number:CaltechAUTHORS:20160930-152629323
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Official Citation:Chen, J., Viatte, C., Hedelius, J. K., Jones, T., Franklin, J. E., Parker, H., Gottlieb, E. W., Wennberg, P. O., Dubey, M. K., and Wofsy, S. C.: Differential column measurements using compact solar-tracking spectrometers, Atmos. Chem. Phys., 16, 8479-8498, doi:10.5194/acp-16-8479-2016, 2016.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:70728
Deposited By: George Porter
Deposited On:03 Oct 2016 17:30
Last Modified:11 Nov 2021 04:33

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