Constraining Emissions of Methane in Utahs Uintah Basin

Constraining Emissions of Methane in Utahs Uintah Basin

Constraining Emissions of Methane in Utahs Uintah Basin with Ground-based Concentration
Observations and a Time-Reversed Lagrangian Transport Model (STILT)
Christopher S. Foster ([email protected])1, Erik Crosman1, Lacey Holland2, Derek Mallia1, Ben Fasoli1, Ryan Bares1, John Horel1, John Lin1
The University of Utah, Department of Atmospheric Sciences, 2The University of Hawaii at Manoa, Department of Atmospheric Sciences

Motivation and Goals:

CH4 Concentration (ppm)

The Uintah Basin produces approximately 1%
of the total U.S. natural gas, but it is
suggested to be unique in its large leak rate,
~10% (6.2-11.7%) of the production amount
(Karion et al. 2013)
Foster et al. 2017 examined the accuracy of
two CH4 emission inventories within the
Uintah Basin and found the NOAA inventory
to better characterize the spatial distribution
of emissions than the EPA

Foster et al. 2017

Observed CH4
(ppm) over two
transects in Sept.
and Nov., 2017



Basin CH4 WFR-STILT Modeling (Foster et al. 2017)

Observational Analysis 2015-2018
1) How do concentrations vary as a function of time of day, time of year, and year to year?



Mobile Observations:




FRU excellent background site,
remaining below 2 ppm on
average except in the winter
stagnation periods in basin
HPL generally experiences
higher concentrations than
other two basin sites
During transitional seasons
(spring and fall), HPL and ROO
observe higher concentrations
than in the summer this is
likely due to increase stability
and shorter days/longer nights
In the summer, daytime
minimum concentrations
return to near background
CSP has a similar diurnal cycle
to ROO in the spring and HPL
in the winter possibly due to
a combination of meteorology
and emissions in region
CH4 diurnal cycles are
impacted by meteorological
patterns boundary-layer
height, local and synopticscale flows


Uintah Basin
(a) Emission rate of CH4 (micromole m-2 s-1) within Utahs Uintah Basin, at 4 km resolution from NOAA. (b) As in (a), except at 0.1 degree resolution from
EPA. Location of gas and oil wells shown as light


Foster et al. 2017 analyzed data from April
and May, 2015
There are currently ~ 3 years worth of CH4
data available at 3 sites within the Uintah
Basin: Fruitland (FRU), Roosevelt (ROO),
A 4th, supplementary site, Castlepeak (CSP),
operated between Nov. 2015 and May 2016
Meteorological data also available at the 4
sites (temperature, wind speed and direction)




Data and Methods:
Foster et al. 2017 study period during
SONGEX (Shale Oil and Natural Gas nEXus)
and JAGUAR (Joint Air and Ground Uintah
basin Air emissions Reconciliation project)
CH4 inventory from Ahmadov et al (2015,
NOAA) and Maasakkers et al. (2016, EPA)
CH4 time series analysis April 2015 present
Missing data is not included in analysis (no
Observational analysis conducted on all days
with a focus on quiescent (light winds) and
non-quiescent conditions
FRU is considered a background site - due to
its location and predominately westerly flow
HPL located to the north of gas wells, ROO is
located within oil wells, CSP located within
more densely situated gas wells

NOAA emission inventory reproduced the
average CH4 diurnal cycle within standard error
at Horsepool and Castlepeak
CH4 concentrations at the three basin sites
(HPL, ROO, CSP) show daily and seasonal
variations consistent with boundary layer
evolution and stability
Higher concentrations are observed at night,
while near background are observed during
the day (slightly elevated above background
during day in transitional seasons)
Meteorological conditions, specifically wind
speed and direction (in addition to boundary
layer evolution), play a key role in observed
CH4 concentrations at the sites

Future Work:
Key future research questions:
2. What are the driving factors in the temporal
variation of observed CH4 concentrations?
3. Can an observational CH4 dataset of this size
be used in conjunction with other available
data to make claims about the state of CH4
emissions within an ONG region?

(a) Average STILT CH4 contribution (log(ppm)) during the time period 18 April
2015 to 31 May 2015 for Horsepool, UT only for quiescent days. (b) As in a,
except for Roosevelt, UT.

Diurnal averages and average contribution
include only quiescent days.
At HPL, EPA nighttime average lower than
both Ahmadov and observations.
Horsepool contribution shows influence
from east-southeast.
Roosevelt contribution shows influence from
Roosevelt unfiltered diurnal average shows
spikes at night indicative of local influence.
When CH4 observations with high relative
standard deviation or simultaneous low
wind speeds are filtered out, spikes in
diurnal average at night are removed.
Simulations perform better at Horsepool
than Roosevelt, where nighttime maxes are
under simulated by both inventories.
At CSP, NOAA nighttime average closer to
observation than EPA, which underestimates
nighttime by ~0.3 ppm.


Average methane concentration at each hour of the day
(MST) during the period 18 April 2015 to 31 May 2015 on
quiescent days. Red lines represent observation, the red
dashed line represents unfiltered observations, blue lines
represent simulation using NOAA inventory, green lines
represent EPA inventory. Standard error shaded on each line.
(a) Roosevelt. (b) Horsepool. (c) Castlepeak.

The winter is characterized by
multi-day episodes with
elevated CH4 concentrations
These periods are the result of
cold-air pooling within the
basin, which causes pollutants
(CH4 and others) to build up
over many days and synoptic
scale disturbances clean out
the elevated concentrations
The build up of CH4 from 28
Nov. 11 Dec. 2015 was
gradual (2 ppm to 6+ ppm at
all 3 sites) over the roughly 2
week period, while the
cleanout was much shorter
Diurnal patterns are still seen
superimposed within the
gradual build up
FRU also experiences some
elevation above background

This study was supported by NOAA Climate
Program Offices Atmospheric Chemistry,
Carbon Cycle, and Climate program, award
Utah Department of Environmental Quality.
Ben Fasoli and Ryan Bares for his help with the
Derek Mallia for his help setting up and running
the STILT model
John Horel for his help with ceilometer data
Seth Lyman for assistance with observations

Selected References:
Ahmadov, R., and Coauthors, 2015: Understanding high wintertime
ozone pollution events in an oil- and natural gas-producing region of
the western US. Atmos. Chem. Phys., doi:10.5194/acp-15-411-2015.
Karion, A., and Coauthors, 2013: Methane emissions estimate from
airborne measurements over a western United States natural gas field.
Geophys. Res. Lett., 40, 43934397, doi:10.1002/grl.50811.
Lin, J. C., C. Gerbig, S. C. Wofsy, A. E. Andrews, B. C. Daube, K. J. Davis,
and C. A. Grainger, 2003: A near-field tool for simulating the upstream
influence of atmospheric observations: The Stochastic Time-Inverted
Lagrangian Transport (STILT) model. J. Geophys. Res, 108,
Maasakkers, J. D. and Coauthors, 2016: Gridded National Inventory of
U.S. Methane Emissions. Environ. Sci. Technol., 23, doi:

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