scholarly journals Methane source attribution in a U.S. dry gas basin using spatial patterns of ground and airborne ethane and methane measurements

Elem Sci Anth ◽  
2019 ◽  
Vol 7 ◽  
Author(s):  
Ingrid Mielke-Maday ◽  
Stefan Schwietzke ◽  
Tara I. Yacovitch ◽  
Benjamin Miller ◽  
Steve Conley ◽  
...  
Keyword(s):  
Source Attribution ◽  
Bottom Up ◽  
Fayetteville Shale ◽  
Airborne Measurements ◽  
Ch4 Emissions ◽  
Mixing Ratios ◽  
Methane Source ◽  
Methane Enhancement ◽  
Western Half

An intensive coordinated airborne and ground-based measurement study was conducted in the Fayetteville Shale in northwestern Arkansas during September and October 2015 to compare and explain potential discrepancies between top-down and bottom-up estimates of regional natural gas (NG) methane (CH4) emissions. In situ mobile downwind measurements are used to document the ethane to methane enhancement ratios (ERs) in emission plumes from NG operations in the region. Enhancement ratios are low (<2% for 87% of NG sources sampled) in this dry gas-producing region and normally distributed around 1.3% in the western half of the study area. A few sampled landfills emitted CH4 but no ethane (C2H6). Sampling drives around large chicken farms, prevalent in the region, did not detect significant downwind CH4 enhancements. In situ airborne measurements of C2H6 and CH4 from area-scale surveys over and downwind of the region documented the resulting ERs from a mix of CH4 sources. Based on these measurements, we show that on average during the measurement windows 85–95% of total CH4 emissions in the western half of the Fayetteville Shale originated from NG sources, which agrees well with bottom-up estimates from the same field study. Lower mixing ratios measured over the eastern half of the region did not support the ER analysis due to the low signal-to-noise on C2H6 measurements.

scholarly journals Tunable diode laser in-situ CH<sub>4</sub> measurements aboard the CARIBIC passenger aircraft: instrument performance assessment

2014 ◽  
Vol 7 (3) ◽  
pp. 743-755 ◽  
Author(s):  
C. Dyroff ◽  
A. Zahn ◽  
S. Sanati ◽  
E. Christner ◽  
A. Rauthe-Schöch ◽  
...  
Keyword(s):  
Lower Troposphere ◽  
Correlation Study ◽  
Tunable Diode Laser ◽  
Long Distance ◽  
Airborne Measurements ◽  
Mixing Ratios ◽  
Flight Level ◽  
Passenger Aircraft ◽  
The Tropics

Abstract. A laser spectrometer for automated monthly measurements of methane (CH4) mixing ratios aboard the CARIBIC passenger aircraft is presented. The instrument is based on a commercial Fast Greenhouse Gas Analyser (FGGA, Los Gatos Res.), which was adapted to meet the requirements imposed by unattended airborne operation. It was characterised in the laboratory with respect to instrument stability, precision, cross sensitivity to H2O, and accuracy. For airborne operation, a calibration strategy is described that utilises CH4 measurements obtained from flask samples taken during the same flights. The precision of airborne measurements is 2 ppb for 10 s averages. The accuracy at aircraft cruising altitude is 3.85 ppb. During aircraft ascent and descent, where no flask samples were obtained, instrumental drifts can be less accurately determined and the uncertainty is estimated to be 12.4 ppb. A linear humidity bias correction was applied to the CH4 measurements, which was most important in the lower troposphere. On average, the correction bias was around 6.5 ppb at an altitude of 2 km, and negligible at cruising flight level. Observations from 103 long-distance flights are presented that span a large part of the northern hemispheric upper troposphere and lowermost stratosphere (UT/LMS), with occasional crossing of the tropics on flights to southern Africa. These accurate data mark the largest UT/LMS in-situ CH4 dataset worldwide. An example of a tracer-tracer correlation study with ozone is given, highlighting the possibility for accurate cross-tropopause transport analyses.

scholarly journals Top-down and Bottom-up aerosol-cloud-closure: towards understanding sources of uncertainty in deriving cloud radiative flux

2017 ◽  
Author(s):  
Kevin J. Sanchez ◽  
Greg C. Roberts ◽  
Radiance Calmer ◽  
Keri Nicoll ◽  
Eyal Hashimshoni ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Radiative Flux ◽  
Research Station ◽  
Top Down ◽  
Bottom Up ◽  
Airborne Measurements ◽  
Aerosol Cloud ◽  
Microphysical Properties ◽  
Holistic Understanding

Abstract. Top-down and bottom-up aerosol-cloud-radiative flux closures were conducted at the Mace Head atmospheric research station in Galway, Ireland in August 2015. This study is part of the BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding) European collaborative project, with the goal of understanding key processes affecting aerosol-cloud-radiative flux closures to improve future climate predictions and develop sustainable policies for Europe. Instrument platforms include ground-based, unmanned aerial vehicles (UAV), and satellite measurements of aerosols, clouds and meteorological variables. The ground-based and airborne measurements of aerosol size distributions and cloud condensation nuclei (CCN) concentration were used to initiate a 1D microphysical aerosol-cloud parcel model (ACPM). UAVs were equipped for a specific science mission, with an optical particle counter for aerosol distribution profiles, a cloud sensor to measure cloud extinction, or a 5-hole probe for 3D wind vectors. UAV cloud measurements are rare and have only become possible in recent years through the miniaturization of instrumentation. These are the first UAV measurements at Mace Head. ACPM simulations are compared to in-situ cloud extinction measurements from UAVs to quantify closure in terms of cloud radiative flux. Two out of seven cases exhibit sub-adiabatic vertical temperature profiles within the cloud, which suggests that entrainment processes affect cloud microphysical properties and lead to an overestimate of simulated cloud radiative flux. Including an entrainment parameterization and explicitly calculating the entrainment fraction in the ACPM simulations both improved cloud-top radiative closure. Entrainment reduced the difference between simulated and observation-derived cloud-top radiative flux (δRF) by between 30 W m−2 and 40 W m−2. After accounting for entrainment, satellite-derived cloud droplet number concentrations (CDNC) were within 30 % of simulated CDNC. In cases with a well-mixed boundary layer, δRF is less than 25 W m−2 after accounting for cloud-top entrainment, compared to less than 50 W m−2 when entrainment is not taken into account. In cases with a decoupled boundary layer, cloud microphysical properties are inconsistent with ground-based aerosol measurements, as expected, and δRF is as high as 88 W m−2, even after accounting for cloud-top entrainment. This work demonstrates the need to take in-situ measurements of aerosol properties for cases where the boundary layer is decoupled as well as consider cloud-top entrainment to accurately model stratocumulus cloud radiative flux.

scholarly journals Top-down and bottom-up aerosol–cloud closure: towards understanding sources of uncertainty in deriving cloud shortwave radiative flux

2017 ◽  
Vol 17 (16) ◽  
pp. 9797-9814 ◽  
Author(s):  
Kevin J. Sanchez ◽  
Gregory C. Roberts ◽  
Radiance Calmer ◽  
Keri Nicoll ◽  
Eyal Hashimshoni ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Radiative Flux ◽  
Research Station ◽  
Top Down ◽  
Bottom Up ◽  
Airborne Measurements ◽  
Aerosol Cloud ◽  
Microphysical Properties ◽  
Holistic Understanding

Abstract. Top-down and bottom-up aerosol–cloud shortwave radiative flux closures were conducted at the Mace Head Atmospheric Research Station in Galway, Ireland, in August 2015. This study is part of the BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding) European collaborative project, with the goal of understanding key processes affecting aerosol–cloud shortwave radiative flux closures to improve future climate predictions and develop sustainable policies for Europe. Instrument platforms include ground-based unmanned aerial vehicles (UAVs)1 and satellite measurements of aerosols, clouds and meteorological variables. The ground-based and airborne measurements of aerosol size distributions and cloud condensation nuclei (CCN) concentration were used to initiate a 1-D microphysical aerosol–cloud parcel model (ACPM). UAVs were equipped for a specific science mission, with an optical particle counter for aerosol distribution profiles, a cloud sensor to measure cloud extinction or a five-hole probe for 3-D wind vectors. UAV cloud measurements are rare and have only become possible in recent years through the miniaturization of instrumentation. These are the first UAV measurements at Mace Head. ACPM simulations are compared to in situ cloud extinction measurements from UAVs to quantify closure in terms of cloud shortwave radiative flux. Two out of seven cases exhibit sub-adiabatic vertical temperature profiles within the cloud, which suggests that entrainment processes affect cloud microphysical properties and lead to an overestimate of simulated cloud shortwave radiative flux. Including an entrainment parameterization and explicitly calculating the entrainment fraction in the ACPM simulations both improved cloud-top radiative closure. Entrainment reduced the difference between simulated and observation-derived cloud-top shortwave radiative flux (δRF) by between 25 and 60 W m−2. After accounting for entrainment, satellite-derived cloud droplet number concentrations (CDNCs) were within 30 % of simulated CDNC. In cases with a well-mixed boundary layer, δRF is no greater than 20 W m−2 after accounting for cloud-top entrainment and up to 50 W m−2 when entrainment is not taken into account. In cases with a decoupled boundary layer, cloud microphysical properties are inconsistent with ground-based aerosol measurements, as expected, and δRF is as high as 88 W m−2, even high (> 30 W m−2) after accounting for cloud-top entrainment. This work demonstrates the need to take in situ measurements of aerosol properties for cases where the boundary layer is decoupled as well as consider cloud-top entrainment to accurately model stratocumulus cloud radiative flux. 1The regulatory term for UAV is remotely piloted aircraft (RPA).

scholarly journals Tunable diode laser in-situ CH<sub>4</sub> measurements aboard the CARIBIC passenger aircraft: instrument performance assessment

2013 ◽  
Vol 6 (5) ◽  
pp. 9225-9261 ◽  
Author(s):  
C. Dyroff ◽  
A. Zahn ◽  
S. Sanati ◽  
E. Christner ◽  
A. Rauthe-Schöch ◽  
...  
Keyword(s):  
Lower Troposphere ◽  
Correlation Study ◽  
Tunable Diode Laser ◽  
Long Distance ◽  
Airborne Measurements ◽  
Mixing Ratios ◽  
Laboratory Characterization ◽  
Passenger Aircraft ◽  
The Tropics

Abstract. A laser spectrometer for automated monthly measurements of methane (CH4) mixing ratios aboard the CARIBIC passenger aircraft is presented. The instrument is based on a commercial Fast Greenhouse Gas Analyzer (FGGA, Los Gatos Res.), which was adapted to meet the requirements imposed by unattended airborne employment. The modified instrument is described. A laboratory characterization was performed to determine the instrument stability, precision, cross sensitivity to H2O, and accuracy. For airborne operation a calibration strategy is described, that utilizes CH4 measurements obtained from flask samples taken during the same flights. The precision of airborne measurements is 2 ppbv for 10 s averages. The accuracy at aircraft cruising altitude is 3.85 ppbv. During aircraft ascent and descent, where no flask samples were obtained, instrumental drifts can be less accurately considered and the uncertainty is estimated to be 12.4 ppbv. A linear humidity bias correction was applied to the CH4 measurements, which was most important in the lower troposphere. On average, the correction bias was around 6.5 ppbv at an altitude of 2 km, and negligible at cruising flight level. Observations from 103 long-distance flights are presented that span a large part of the northern hemispheric upper troposphere and lowermost stratosphere (UT/LMS), with occasional crossing of the tropics on flights to southern Africa. These accurate data mark the largest UT/LMS in-situ CH4 dataset worldwide. An example of a tracer-tracer correlation study with ozone is given, highlighting the possibility for accurate cross-tropopause transport analyses.

scholarly journals HO<sub>x</sub> measurements in the summertime upper troposphere over Europe: a comparison of observations to a box model and a 3-D model

2012 ◽  
Vol 12 (11) ◽  
pp. 30619-30660 ◽  
Author(s):  
E. Regelin ◽  
H. Harder ◽  
M. Martinez ◽  
D. Kubistin ◽  
C. Tatum Ernest ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Circulation Model ◽  
Box Model ◽  
Measurement Unit ◽  
Data Set ◽  
Upper Troposphere ◽  
Sources And Sinks ◽  
Airborne Measurements ◽  
Mixing Ratios

Abstract. In-situ airborne measurements of OH and HO2 with the HORUS (HydrOxyl Radical measurement Unit based on fluorescence Spectroscopy) instrument were performed in the summertime upper troposphere across Europe during the HOOVER 2 (HOx OVer EuRope) campaign in July 2007. Complementary measurements of trace gas species and photolysis frequencies were conducted to obtain a broad data set, which has been used to quantify the significant HOx sources and sinks. In this study we compare the in-situ measurement of OH and HO2 with simulated mixing ratios from the constrained box model CAABA/MECCA (Chemistry As A Box Model Application/Module Efficiently Calculating the Chemistry of the Atmosphere), and the global circulation model EMAC (ECHAM5/MESSy Atmospheric Chemistry Model). The constrained box model reproduces the observed OH and HO2 mixing ratios with better agreement (obs/mod median 98% OH, 96% HO2) than the global model (median 76% OH, 59% HO2). The observations and the computed HOx sources and sinks are used to identify deviations between the models and their impacts on the calculated HOx budget.

scholarly journals Validation of routine continuous airborne CO<sub>2</sub> observations near the Bialystok Tall Tower

2011 ◽  
Vol 4 (6) ◽  
pp. 6987-7034 ◽  
Author(s):  
H. Chen ◽  
J. Winderlich ◽  
C. Gerbig ◽  
K. Katrynski ◽  
A. Jordan ◽  
...  
Keyword(s):  
Sampling Strategy ◽  
Atmospheric Variability ◽  
Weighting Functions ◽  
Airborne Measurements ◽  
Mixing Ratios ◽  
Temporal And Spatial Variability ◽  
Temporal Averaging ◽  
Northeastern Poland ◽  
Temporal And Spatial

Abstract. Since 2002 in situ airborne measurements of atmospheric CO2 mixing ratios have been performed regularly aboard a rental aircraft near Bialystok (53°08' N, 23°09' E), a city in northeastern Poland. Since August 2008, the in situ CO2 measurements have been made by a modified commercially available and fully automated non-dispersive infrared (NDIR) analyzer system. The response of the analyzer has been characterized and the CO2 mixing ratio stability of the associated calibration system has been fully tested, which results in an optimal calibration strategy and allows for an accuracy of the CO2 measurements within 0.2 ppm. Besides the in situ measurements, air samples have been collected in glass flasks and analyzed in the laboratory for mixing ratios of CO2, CO, CH4, N2O, H2, SF6 and for isotopic ratios of δ13C and δ18O in CO2. To validate the in situ CO2 measurements against reliable discrete flask measurements, we developed weighting functions that mimic the temporal averaging of the flask sampling process. Comparisons between in situ and flask CO2 measurements demonstrate that these weighting functions can compensate for atmospheric variability, and provide an effective method for validating airborne in situ CO2 measurements. In addition, we show the nine-year records of flask CO2 measurements, from which the CO2 increase rates are computed for the 300 m level (1.59 ± 0.21 ppm yr−1) and for the 2500 m level (1.77 ± 0.08 ppm yr−1). The new system, automated since August 2008, has eliminated the need for manual in-flight calibrations, and thus enables an additional vertical profile, 20 km away, to be sampled at no additional cost in terms of flight hours. This sampling strategy provides an opportunity to investigate both temporal and spatial variability on a regular basis.

scholarly journals HOx measurements in the summertime upper troposphere over Europe: a comparison of observations to a box model and a 3-D model

2013 ◽  
Vol 13 (21) ◽  
pp. 10703-10720 ◽  
Author(s):  
E. Regelin ◽  
H. Harder ◽  
M. Martinez ◽  
D. Kubistin ◽  
C. Tatum Ernest ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Circulation Model ◽  
Box Model ◽  
Measurement Unit ◽  
Data Set ◽  
Upper Troposphere ◽  
Sources And Sinks ◽  
Airborne Measurements ◽  
Mixing Ratios

Abstract. In situ airborne measurements of OH and HO2 with the HORUS (HydrOxyl Radical measurement Unit based on fluorescence Spectroscopy) instrument were performed in the summertime upper troposphere across Europe during the HOOVER 2 (HOx OVer EuRope) campaign in July 2007. Complementary measurements of trace gas species and photolysis frequencies were conducted to obtain a broad data set, which has been used to quantify the significant HOx sources and sinks. In this study we compare the in situ measurement of OH and HO2 with simulated mixing ratios from the constrained box model CAABA/MECCA (Chemistry As A Box Model Application/Module Efficiently Calculating the Chemistry of the Atmosphere), and the global circulation model EMAC (ECHAM5/MESSy Atmospheric Chemistry Model). The constrained box model reproduces the observed OH and HO2 mixing ratios with better agreement (obs/mod median 98% OH, 96% HO2) than the global model (median 76% OH, 59% HO2). The observations and the computed HOx sources and sinks are used to identify deviations between the models and their impacts on the calculated HOx budget.

scholarly journals Representativeness of the IAGOS airborne measurements in the lower troposphere

Elem Sci Anth ◽  
2018 ◽  
Vol 6 ◽  
Author(s):  
H. Petetin ◽  
M. Jeoffrion ◽  
B. Sauvage ◽  
G. Athier ◽  
R. Blot ◽  
...  
Keyword(s):  
Air Quality ◽  
Lower Troposphere ◽  
Monitoring Network ◽  
Ratio Distribution ◽  
Airborne Measurements ◽  
Mixing Ratios ◽  
The Difference ◽  
The Vertical Distribution ◽  
Local Emissions

In the framework of the In Service Aircraft for Global Observing System (IAGOS) program, airborne in-situ O3 and CO measurements are performed routinely using in-service aircraft, providing vertical profiles from the surface to about 10–12 km. Due to the specificity of IAGOS measurements (measurements around busy international airports), uncertainties exist on their representativeness in the lower troposphere as they may be impacted by emissions related to airport activities and/or other aircraft. In this study, we thus investigate how the IAGOS measurements in the lower troposphere compare with nearby surface stations (from the local Air Quality monitoring network (AQN)) and more distant regional surface stations (from the Global Atmospheric Watch (GAW) network). The study focuses on Frankfurt but some results at other European airports (Vienna, Paris) are also discussed. Results indicate that the IAGOS observations close to the surface do not appear to be strongly impacted by local emissions related to airport activities. In terms of mixing ratio distribution, seasonal variations and trends, the CO and O3 mixing ratios measured by IAGOS in the first few hundred metres above the surface have similar characteristics to the mixing ratios measured at surrounding urban background stations. Higher in altitude, both the difference with data from the local AQN and the consistency with the GAW regional stations are higher, which indicates a larger representativeness of the IAGOS data. Despite few quantitative differences with Frankfurt, consistent results are obtained in the two other cities Vienna and Paris. Based on 11 years of data (2002–2012), this study thus demonstrates that IAGOS observations in the lowest troposphere can be used as a complement to surface stations to study the air quality in/around the agglomeration, providing important information on the vertical distribution of pollution.

scholarly journals Validation of routine continuous airborne CO<sub>2</sub> observations near the Bialystok Tall Tower

2012 ◽  
Vol 5 (4) ◽  
pp. 873-889 ◽  
Author(s):  
H. Chen ◽  
J. Winderlich ◽  
C. Gerbig ◽  
K. Katrynski ◽  
A. Jordan ◽  
...  
Keyword(s):  
Sampling Strategy ◽  
Atmospheric Variability ◽  
Weighting Functions ◽  
Airborne Measurements ◽  
Mixing Ratios ◽  
Temporal And Spatial Variability ◽  
Temporal Averaging ◽  
Northeastern Poland ◽  
Temporal And Spatial

Abstract. Since 2002 in situ airborne measurements of atmospheric CO2 mixing ratios have been performed regularly aboard a rental aircraft near Bialystok (53°08´ N, 23°09´ E), a city in northeastern Poland. Since August 2008, the in situ CO2 measurements have been made by a modified commercially available and fully automated non-dispersive infrared (NDIR) analyzer system. The response of the analyzer has been characterized and the CO2 mixing ratio stability of the associated calibration system has been fully tested, which results in an optimal calibration strategy and allows for an accuracy of the CO2 measurements within 0.2 ppm. Besides the in situ measurements, air samples have been collected in glass flasks and analyzed in the laboratory for CO2 and other trace gases. To validate the in situ CO2 measurements against reliable discrete flask measurements, we developed weighting functions that mimic the temporal averaging of the flask sampling process. Comparisons between in situ and flask CO2 measurements demonstrate that these weighting functions can compensate for atmospheric variability, and provide an effective method for validating airborne in situ CO2 measurements. In addition, we show the nine-year records of flask CO2 measurements. The new system, automated since August 2008, has eliminated the need for manual in-flight calibrations, and thus enables an additional vertical profile, 20 km away, to be sampled at no additional cost in terms of flight hours. This sampling strategy provides an opportunity to investigate both temporal and spatial variability on a regular basis.

scholarly journals Cell-free protein synthesis and in situ immobilization of deGFP-MatB in polymer microgels for malonate-to-malonyl CoA conversion

RSC Advances ◽  
2020 ◽  
Vol 10 (66) ◽  
pp. 40588-40596
Author(s):  
Tony Köhler ◽  
Thomas Heida ◽  
Sandra Hoefgen ◽  
Niclas Weigel ◽  
Vito Valiante ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Genetic Information ◽  
In Situ Immobilization ◽  
Bottom Up ◽  
Free Protein ◽  
Malonyl Coa ◽  
Cell Free Protein Synthesis

We describe a bottom-up approach towards functional enzymes utilizing microgels as carriers for genetic information that enable cell-free protein synthesis, in situ immobilization, and utilization of functional deGFP-MatB.

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