Journal of Geophysical Research: Atmospheres
Supporting information for
Airborne flux measurements of methane and volatile organic compounds (VOCs) over oil
and gas producing regions in the United States
Bin Yuan1,2,*, Lisa Kaser3, Thomas Karl4, Martin Graus1,2,4, Jeff Peischl1,2, Teresa L. Campos3,
Steve Shertz3, Eric C. Apel3, Rebecca S. Hornbrook3, Alan Hills3, Jessica B. Gilman1,2, Brian M.
Lerner1,2, Carsten Warneke1,2, Frank M. Flocke3, Thomas B. Ryerson1, Alex B. Guenther3,5,
Joost A. de Gouw1,2,6
1.
2.
NOAA Earth System Research Laboratory, Chemical Sciences Division, Boulder, CO, USA
Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, Boulder, CO,
USA
3.
Atmospheric Chemistry Division (ACD), National Center for Atmospheric Research, Boulder, CO, USA
4.
5.
Institute of Meteorology and Geophysics, University of Innsbruck, Innsbruck, Austria
Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA, USA
6.
Department of Chemistry and Biochemistry, University of Colorado at Boulder, CO, USA
Contents of this file
Figures S1 to S8
Table S1
Introduction
This file includes eight additional figures and one additional table.
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Figure S1. Flight track of the NOAA WP-3D over the Marcellus shale play on 6 July during
SENEX. The purple and brown dots are locations of unconventional and conventional wells,
respectively.
Figure S2. Wavelet cross spectra of CH4 with vertical wind speed (left column) and benzene
with vertical wind speed (right column) along the flight leg during the first cycle of triangle flight
pattern during the C-130 flight on 4 July. Top: time series of the VOC species (CH4 or benzene)
and vertical wind speed; Middle: the two-dimensional wavelet cross spectra. The y-axis is the
time scale of the cross spectra. The dashed white lines indicate the cone of influence (COI)
[Torrence and Compo, 1998]; Bottom: Time series of CWT flux results. The dashed lines
indicate zero flux.
2
Figure S3. CWT fluxes of benzene (A) and CH4 (B) during the C-130 flight on 27 June. The dots
are color-coded and size-coded using the fluxes of benzene and CH4, respectively. The arrows
in the graphs indicate the horizontal wind directions.
Figure. S4. Google Earth image (taken on 27 Mar., 2013) of a large facility (31.488 N, 94.638
W), 1.6 km upwind of a CH4 flux hotspot (31.502 N, 94.635 W) observed at ~17:30 pm (UTC) on
June 25, 2013. Historical images indicate that the facility was built between Feb. 2009 and Nov.
2011.
3
Figure S5. (A) Flight track of the C-130 on 5 July, 2013 during NOMADSS. The dashed box
shows measurements in the marine boundary layer. (B) Time series of CWT CH4 fluxes
determined from the marine boundary layer data.
Figure. S6. Histograms of CWT flux results from the synthetic datasets. Blue curves are fitting
results using Voigt function. Black points are residuals from Voigt fits. Numbers in the graphs
are standard deviations of input concentrations.
4
Figure S7. (A) Histogram of measured CH4 emissions from Barnett shale gas well sites in Fort
Worth City [Alvarez et al., 2012; Eastern Research Group and Sage Environmental Consulting,
2011]. The equivalent CH4 emission flux with a unit of μg m-2 s-1 in Fort Worth City is also
calculated from CH4 emissions and well pad density in the area (375 well pads and 904.4 km2).
The equivalent CH4 flux is shown in the top axis. (B) Histogram of measured CH4 emissions
from equipment components [National Gas Machinery Laboratory, 2006] of gas processing
plants. The blue lines are lognormal fits to the black points.
Figure S8. Time series of CWT CH4 fluxes and the identified ten highest peaks (THP) (blue
lines) from the NOAA WP-3D flights on 10 June (A), 25 June (B) and 6 July (C), respectively.
5
Masses
Mass attributions
27 June
4 July
m/z 21
m/z 37
H318O+
0.05
0.1
0.05
0.05
0.1
0.1
0.1
0.1
0.1
0.1
---
0.1
0.1
0.1
0.1
--
0.1
(H218O)H3O+
Isoprene and cyclohexane
fragments
MVK, MACR and cyclohexane
m/z 71
fragments
m/z 79
Benzene
m/z 93
Toluene
m/z 81
Monoterpenes
m/z 137
Monoterpenes
2-methyl-3-butene-2-ol and other
unsaturated oxygenates
m/z 87
(pentanal, petanones,
methylacrylic acid)
“--” indicate the masses are not measured.
m/z 69
Table S1. The masses measured and their dwelling time in PTR-MS onboard C-130 at flux
mode. Expected compounds contributing to measured signals of various PTR-MS masses in oil
and gas production regions are also listed.
References:
Alvarez, R. A., S. W. Pacala, J. J. Winebrake, W. L. Chameides, and S. P. Hamburg (2012),
Greater focus needed on methane leakage from natural gas infrastructure, Proceedings of the
National Academy of Sciences, 109(17), 6435-6440.
Eastern Research Group, and Sage Environmental Consulting (2011), City of Fort Worth Natural
Gas Air Quality Study Available at
http://fortworthtexas.gov/gaswells/default.aspx?id=87074.Rep.
National Gas Machinery Laboratory, C. E., Innovative Environmental Solutions (2006), CostEffective Directed Inspection and Maintenance Control Opportunities at Five Gas Processing
Plants and Upstream Gathering Compressor Stations and Well SitesRep., EPA.
Torrence, C., and G. P. Compo (1998), A Practical Guide to Wavelet Analysis, Bulletin of the
American Meteorological Society, 79(1), 61-78.
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