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Tran H, Polka E, Buonocore JJ, Roy A, Trask B, Hull H, Arunachalam S. Air Quality and Health Impacts of Onshore Oil and Gas Flaring and Venting Activities Estimated Using Refined Satellite-Based Emissions. GEOHEALTH 2024; 8:e2023GH000938. [PMID: 38449816 PMCID: PMC10916426 DOI: 10.1029/2023gh000938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 01/28/2024] [Accepted: 01/31/2024] [Indexed: 03/08/2024]
Abstract
Emissions from flaring and venting (FV) in oil and gas (O&G) production are difficult to quantify due to their intermittent activities and lack of adequate monitoring and reporting. Given their potentially significant contribution to total emissions from the O&G sector in the United States, we estimate emissions from FV using Visible Infrared Imaging Radiometer Suite satellite observations and state/local reported data on flared gas volume. These refined estimates are higher than those reported in the National Emission Inventory: by up to 15 times for fine particulate matter (PM2.5), two times for sulfur dioxides, and 22% higher for nitrogen oxides (NOx). Annual average contributions of FV to ozone (O3), NO2, and PM2.5 in the conterminous U.S. (CONUS) are less than 0.15%, but significant contributions of up to 60% are found in O&G fields with FV. FV contributions are higher in winter than in summer months for O3 and PM2.5; an inverse behavior is found for NO2. Nitrate aerosol contributions to PM2.5 are highest in the Denver basin whereas in the Permian and Bakken basins, sulfate and elemental carbon aerosols are the major contributors. Over four simulated months in 2016 for the entire CONUS, FV contributes 210 additional instances of exceedances to the daily maximum 8-hr average O3 and has negligible contributions to exceedance of NO2 and PM2.5, given the current form of the national ambient air quality standards. FV emissions are found to cause over $7.4 billion in health damages, 710 premature deaths, and 73,000 asthma exacerbations among children annually.
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Affiliation(s)
- Huy Tran
- Institute for the EnvironmentThe University of North Carolina at Chapel HillChapel HillNCUSA
| | - Erin Polka
- Department of Environmental HealthBoston University School of Public HealthBostonMAUSA
| | - Jonathan J. Buonocore
- Department of Environmental HealthBoston University School of Public HealthBostonMAUSA
| | - Ananya Roy
- Environmental Defense FundWashingtonDCUSA
| | - Beth Trask
- Environmental Defense FundWashingtonDCUSA
| | | | - Saravanan Arunachalam
- Institute for the EnvironmentThe University of North Carolina at Chapel HillChapel HillNCUSA
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2
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Plant G, Kort EA, Gorchov Negron AM, Chen Y, Fordice G, Harkins C. In Situ Sampling of NOx Emissions from United States Natural Gas Flares Reveals Heavy-Tail Emission Characteristic. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:1509-1517. [PMID: 38189232 PMCID: PMC10809782 DOI: 10.1021/acs.est.3c08095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 01/09/2024]
Abstract
Natural gas flaring is a common practice employed in many United States (U.S.) oil and gas regions to dispose of gas associated with oil production. Combustion of predominantly hydrocarbon gas results in the production of nitrogen oxides (NOx). Here, we present a large field data set of in situ sampling of real world flares, quantifying flaring NOx production in major U.S. oil production regions: the Bakken, Eagle Ford, and Permian. We find that a single emission factor does not capture the range of the observed NOx emission factors within these regions. For all three regions, the median emission factors fall within the range of four emission factors used by the Texas Commission for Environmental Quality. In the Bakken and Permian, the distribution of emission factors exhibits a heavy tail such that basin-average emission factors are 2-3 times larger than the value employed by the U.S. Environmental Protection Agency. Extrapolation to basin scale emissions using auxiliary satellite assessments of flare volumes indicates that NOx emissions from flares are skewed, with 20%-30% of the flares responsible for 80% of basin-wide flaring NOx emissions. Efforts to reduce flaring volume through alternative gas capture methods would have a larger impact on the NOx oil and gas budget than current inventories indicate.
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Affiliation(s)
- Genevieve Plant
- Climate
and Space Sciences and Engineering, University
of Michigan, Ann Arbor, Michigan 48109, United States
| | - Eric A. Kort
- Climate
and Space Sciences and Engineering, University
of Michigan, Ann Arbor, Michigan 48109, United States
| | - Alan M. Gorchov Negron
- Climate
and Space Sciences and Engineering, University
of Michigan, Ann Arbor, Michigan 48109, United States
| | - Yuanlei Chen
- Energy
Science and Engineering, Stanford University, Stanford, California 94305, United States
| | - Graham Fordice
- Climate
and Space Sciences and Engineering, University
of Michigan, Ann Arbor, Michigan 48109, United States
| | - Colin Harkins
- NOAA
Chemical Sciences Laboratory (CSL), Boulder, Colorado 80305, United States
- Cooperative
Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309, United States
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3
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He J, Harkins C, O’Dell K, Li M, Francoeur C, Aikin KC, Anenberg S, Baker B, Brown SS, Coggon MM, Frost GJ, Gilman JB, Kondragunta S, Lamplugh A, Lyu C, Moon Z, Pierce BR, Schwantes RH, Stockwell CE, Warneke C, Yang K, Nowlan CR, González Abad G, McDonald BC. COVID-19 perturbation on US air quality and human health impact assessment. PNAS NEXUS 2024; 3:pgad483. [PMID: 38222466 PMCID: PMC10785034 DOI: 10.1093/pnasnexus/pgad483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 12/21/2023] [Indexed: 01/16/2024]
Abstract
The COVID-19 stay-at-home orders issued in the United States caused significant reductions in traffic and economic activities. To understand the pandemic's perturbations on US emissions and impacts on urban air quality, we developed near-real-time bottom-up emission inventories based on publicly available energy and economic datasets, simulated the emission changes in a chemical transport model, and evaluated air quality impacts against various observations. The COVID-19 pandemic affected US emissions across broad-based energy and economic sectors and the impacts persisted to 2021. Compared with 2019 business-as-usual emission scenario, COVID-19 perturbations resulted in annual decreases of 10-15% in emissions of ozone (O3) and fine particle (PM2.5) gas-phase precursors, which are about two to four times larger than long-term annual trends during 2010-2019. While significant COVID-induced reductions in transportation and industrial activities, particularly in April-June 2020, resulted in overall national decreases in air pollutants, meteorological variability across the nation led to local increases or decreases of air pollutants, and mixed air quality changes across the United States between 2019 and 2020. Over a full year (April 2020 to March 2021), COVID-induced emission reductions led to 3-4% decreases in national population-weighted annual fourth maximum of daily maximum 8-h average O3 and annual PM2.5. Assuming these emission reductions could be maintained in the future, the result would be a 4-5% decrease in premature mortality attributable to ambient air pollution, suggesting that continued efforts to mitigate gaseous pollutants from anthropogenic sources can further protect human health from air pollution in the future.
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Affiliation(s)
- Jian He
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309, USA
- NOAA Chemical Sciences Laboratory, Boulder, CO 80305, USA
| | - Colin Harkins
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309, USA
- NOAA Chemical Sciences Laboratory, Boulder, CO 80305, USA
| | - Katelyn O’Dell
- Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, Washington, DC 20052, USA
| | - Meng Li
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309, USA
- NOAA Chemical Sciences Laboratory, Boulder, CO 80305, USA
| | - Colby Francoeur
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309, USA
- NOAA Chemical Sciences Laboratory, Boulder, CO 80305, USA
- Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Kenneth C Aikin
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309, USA
- NOAA Chemical Sciences Laboratory, Boulder, CO 80305, USA
| | - Susan Anenberg
- Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, Washington, DC 20052, USA
| | - Barry Baker
- NOAA Air Resources Laboratory, College Park, MD 20740, USA
| | - Steven S Brown
- NOAA Chemical Sciences Laboratory, Boulder, CO 80305, USA
| | | | | | | | - Shobha Kondragunta
- NOAA National Environmental Satellite, Data, and Information Service, Center for Satellite Applications and Research, College Park, MD 20740, USA
| | - Aaron Lamplugh
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309, USA
- NOAA Chemical Sciences Laboratory, Boulder, CO 80305, USA
| | - Congmeng Lyu
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309, USA
- NOAA Chemical Sciences Laboratory, Boulder, CO 80305, USA
| | - Zachary Moon
- NOAA Air Resources Laboratory, College Park, MD 20740, USA
- Earth Resources Technology (ERT) Inc., Laurel, MD 20707, USA
| | - Bradley R Pierce
- Space Science and Engineering Center, University of Wisconsin-Madison, Madison, WI 53706, USA
| | | | - Chelsea E Stockwell
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309, USA
- NOAA Chemical Sciences Laboratory, Boulder, CO 80305, USA
| | | | - Kai Yang
- Department of Atmospheric and Oceanic Science, University of Maryland, College Park, MD 20742, USA
| | - Caroline R Nowlan
- Center for Astrophysics, Harvard and Smithsonian, Cambridge, MA 02138, USA
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Abstract
Vehicle exhaust has been acknowledged as an essential factor affecting human health due to the extensive use of cars. Its main components include volatile organic compounds (VOCs) and nitrogen oxides (NOx), which can cause acute irritation and chronic diseases, and significant research on the treatment of vehicle exhaust has received increasing attention in recent decades. Recently, photocatalytic technology has been considered a practical approach for eliminating vehicle emissions. This review highlights the crucial role of photocatalytic technology in eliminating vehicle emissions using semiconductor catalysts. A particular emphasis has been placed on various photocatalytic materials, such as TiO2-based materials, Bi-based materials, and Metal–Organic Frameworks (MOFs), and their recent advances in the performance of VOC and NOx photodegradation. In addition, the applications of photocatalytic technology for the elimination of vehicle exhaust are presented (including photocatalysts combined with pavement surfaces, making photocatalysts into architectural coatings and photoreactors), which will offer a promising strategy for photocatalytic technology to remove vehicle exhaust.
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Prenni AJ, Benedict KB, Day DE, Sive BC, Zhou Y, Naimie L, Gebhart KA, Dombek T, De Boskey M, Hyslop NP, Spencer E, Chew QM, Collett JL, Schichtel BA. Wintertime haze and ozone at Dinosaur National Monument. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION (1995) 2022; 72:951-968. [PMID: 35254216 DOI: 10.1080/10962247.2022.2048922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 01/19/2022] [Accepted: 02/28/2022] [Indexed: 06/14/2023]
Abstract
Dinosaur National Monument (DINO) is located near the northeastern edge of the Uinta Basin and often experiences elevated levels of wintertime ground-level ozone. Previous studies have shown that high ozone mixing ratios in the Uinta Basin are driven by elevated levels of volatile organic compounds (VOCs) and nitrogen oxides (NOx) from regional oil and gas development coupled with temperature inversions and enhanced photochemistry from persistent snow cover. Here, we show that persistent snow cover and temperature inversions, along with abundant ammonia, also lead to wintertime haze in this region. A study was conducted at DINO from November 2018 through May 2020 where ozone, speciated fine and coarse aerosols, inorganic gases, and VOCs were measured. Three National Ambient Air Quality Standards (NAAQS) ozone exceedances were observed in the first winter, and no exceedances were observed in the second winter. In contrast, elevated levels of particulate matter were observed both winters, with 24-h averaged particle light extinction exceeding 100 Mm-1. These haze events were dominated by ammonium nitrate, and particulate organics were highly correlated with ammonium nitrate. Ammonium nitrate formation was limited by nitric acid in winter. As such, reductions in regional NOx emissions should reduce haze levels and improve visibility at DINO in winter. Long-term measurements of particulate matter from nearby Vernal, Utah, suggest that visibility impairment is a persistent issue in the Uinta Basin in winter. From April through October 2019, relatively clean conditions occurred, with average particle extinction of ~10 Mm-1. During this period, ammonium nitrate concentrations were lower by more than an order of magnitude, and contributions from coarse mass and soil to haze levels increased. VOC markers indicated that the high levels of observed pollutants in winter were likely from local sources related to oil and gas extraction activities.Implications: Elevated ground-level ozone and haze levels were observed at Dinosaur National Monument in winter. Haze episodes were dominated by ammonium nitrate, with 24-h averaged particle light extinction exceeding 100 Mm-1, reducing visual range near the surface to ~35 km. Despite elevated ammonium nitrate concentrations, additional gas-phase ammonia was available, such that any increase in NOx emissions in the region is likely to lead to even greater haze levels.
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Affiliation(s)
- Anthony J Prenni
- National Park Service, Air Resources Division, Lakewood, Colorado, USA
| | - Katherine B Benedict
- Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado, USA
| | - Derek E Day
- Cooperative Institute for Research in the Atmosphere (CIRA), Colorado State University, Fort Collins, Colorado, USA
| | - Barkley C Sive
- National Park Service, Air Resources Division, Lakewood, Colorado, USA
| | - Yong Zhou
- Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado, USA
| | - Lilly Naimie
- Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado, USA
| | - Kristi A Gebhart
- National Park Service, Air Resources Division, Lakewood, Colorado, USA
| | - Tracy Dombek
- Analytical Sciences, RTI International, Research Triangle Park, North Carolina, USA
| | - Miranda De Boskey
- Analytical Sciences, RTI International, Research Triangle Park, North Carolina, USA
| | - Nicole P Hyslop
- University of California, Davis, Air Quality Research Center, Davis, California, USA
| | | | | | - Jeffrey L Collett
- Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado, USA
| | - Bret A Schichtel
- National Park Service, Air Resources Division, Lakewood, Colorado, USA
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6
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Francoeur CB, McDonald BC, Gilman JB, Zarzana KJ, Dix B, Brown SS, de Gouw JA, Frost GJ, Li M, McKeen SA, Peischl J, Pollack IB, Ryerson TB, Thompson C, Warneke C, Trainer M. Quantifying Methane and Ozone Precursor Emissions from Oil and Gas Production Regions across the Contiguous US. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:9129-9139. [PMID: 34161066 DOI: 10.1021/acs.est.0c07352] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We present an updated fuel-based oil and gas (FOG) inventory with estimates of nitrogen oxide (NOx) emissions from oil and natural gas production in the contiguous US (CONUS). We compare the FOG inventory with aircraft-derived ("top-down") emissions for NOx over footprints that account for ∼25% of US oil and natural gas production. Across CONUS, we find that the bottom-up FOG inventory combined with other anthropogenic emissions is on average within ∼10% of top-down aircraft-derived NOx emissions. We also find good agreement in the trends of NOx from drilling- and production-phase activities, as inferred by satellites and in the bottom-up inventory. Leveraging tracer-tracer relationships derived from aircraft observations, methane (CH4) and non-methane volatile organic compound (NMVOC) emissions have been added to the inventory. Our total CONUS emission estimates for 2015 of oil and natural gas are 0.45 ± 0.14 Tg NOx/yr, 15.2 ± 3.0 Tg CH4/yr, and 5.7 ± 1.7 Tg NMVOC/yr. Compared to the US National Emissions Inventory and Greenhouse Gas Inventory, FOG NOx emissions are ∼40% lower, while inferred CH4 and NMVOC emissions are up to a factor of ∼2 higher. This suggests that NMVOC/NOx emissions from oil and gas basins are ∼3 times higher than current estimates and will likely affect how air quality models represent ozone formation downwind of oil and gas fields.
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Affiliation(s)
- Colby B Francoeur
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States
- NOAA Chemical Sciences Laboratory, Boulder, Colorado 80305, United States
| | - Brian C McDonald
- NOAA Chemical Sciences Laboratory, Boulder, Colorado 80305, United States
| | - Jessica B Gilman
- NOAA Chemical Sciences Laboratory, Boulder, Colorado 80305, United States
| | - Kyle J Zarzana
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States
- NOAA Chemical Sciences Laboratory, Boulder, Colorado 80305, United States
| | - Barbara Dix
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Steven S Brown
- NOAA Chemical Sciences Laboratory, Boulder, Colorado 80305, United States
| | - Joost A de Gouw
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Gregory J Frost
- NOAA Chemical Sciences Laboratory, Boulder, Colorado 80305, United States
| | - Meng Li
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States
- NOAA Chemical Sciences Laboratory, Boulder, Colorado 80305, United States
| | - Stuart A McKeen
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States
- NOAA Chemical Sciences Laboratory, Boulder, Colorado 80305, United States
| | - Jeff Peischl
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States
- NOAA Chemical Sciences Laboratory, Boulder, Colorado 80305, United States
| | - Ilana B Pollack
- Department of Atmospheric Sciences, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Thomas B Ryerson
- NOAA Chemical Sciences Laboratory, Boulder, Colorado 80305, United States
| | - Chelsea Thompson
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States
- NOAA Chemical Sciences Laboratory, Boulder, Colorado 80305, United States
| | - Carsten Warneke
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States
- NOAA Chemical Sciences Laboratory, Boulder, Colorado 80305, United States
| | - Michael Trainer
- NOAA Chemical Sciences Laboratory, Boulder, Colorado 80305, United States
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7
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Abstract
We measured the spatial distribution and composition of ozone-forming hydrocarbons, alcohols, and carbonyls in Utah’s Uinta Basin during the winter months of 2019 and 2020. The Uinta Basin contains about 10,000 producing oil and gas wells. Snow cover and the region’s unique topography (i.e., a large basin entirely surrounded by mountains) promote strong, multi-day temperature inversion episodes that concentrate pollution and lead to wintertime ozone production. Indeed, organic compound concentrations were about eight times higher during inversion episodes than during snow-free springtime conditions. We examined spatial associations between wintertime concentrations of organics and oil and gas sources in the region, and we found that concentrations of highly reactive alkenes were higher in areas with dense oil production than in areas with dense gas production. Total alkene+acetylene concentrations were 267 (42, 1146; lower and upper 95% confidence limits) µg m−3 at locations with 340 or more producing oil wells within 10 km (i.e., 75th percentile) versus 12 (9, 23) µg m−3 at locations with 15 or fewer oil wells (i.e., 25th percentile). Twenty-eight percent of the potential for organic compounds to produce ozone was due to alkenes in areas with dense oil production. Spatial correlations and organic compound ratios indicated that the most likely source of excess alkenes in oil-producing areas was natural gas-fueled engines, especially lean-burning (i.e., high air:fuel ratio) artificial lift engines.
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8
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de Gouw JA, Veefkind JP, Roosenbrand E, Dix B, Lin JC, Landgraf J, Levelt PF. Daily Satellite Observations of Methane from Oil and Gas Production Regions in the United States. Sci Rep 2020; 10:1379. [PMID: 31992727 PMCID: PMC6987228 DOI: 10.1038/s41598-020-57678-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 01/06/2020] [Indexed: 11/28/2022] Open
Abstract
Production of oil and natural gas in North America is at an all-time high due to the development and use of horizontal drilling and hydraulic fracturing. Methane emissions associated with this industrial activity are a concern because of the contribution to climate radiative forcing. We present new measurements from the space-based TROPOspheric Monitoring Instrument (TROPOMI) launched in 2017 that show methane enhancements over production regions in the United States. In the Uintah Basin in Utah, TROPOMI methane columns correlated with in-situ measurements, and the highest columns were observed over the deepest parts of the basin, consistent with the accumulation of emissions underneath inversions. In the Permian Basin in Texas and New Mexico, methane columns showed maxima over regions with the highest natural gas production and were correlated with nitrogen-dioxide columns at a ratio that is consistent with results from in-situ airborne measurements. The improved detail provided by TROPOMI will likely enable the timely monitoring from space of methane emissions associated with oil and natural gas production.
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Affiliation(s)
- Joost A de Gouw
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, United States. .,Department of Chemistry, University of Colorado, Boulder, CO, United States.
| | - J Pepijn Veefkind
- Royal Netherlands Meteorological Institute, de Bilt, The Netherlands.,Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, The Netherlands
| | - Esther Roosenbrand
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, United States.,Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, The Netherlands
| | - Barbara Dix
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, United States
| | - John C Lin
- Department of Atmospheric Sciences, University of Utah, Salt Lake City, UT, United States
| | - Jochen Landgraf
- SRON Netherlands Institute for Space Research, Utrecht, The Netherlands
| | - Pieternel F Levelt
- Royal Netherlands Meteorological Institute, de Bilt, The Netherlands.,Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, The Netherlands
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