Sciences and Exploration Directorate

Bryan N. Duncan


Bryan N. Duncan's Contact Card & Information.
Phone: 301.614.5994
Org Code: 614
Mail Code 614
Greenbelt, MD 20771

Missions & Projects

Brief Bio

Dr. Bryan N. Duncan is an atmospheric scientist in the Atmospheric Chemistry and Dynamics Laboratory (ACDL) at NASA Goddard Space Flight Center. He is Project Scientist for the NASA Aura satellite mission, which observes atmospheric constituents in the troposphere, stratosphere and mesosphere. He has expertise in air quality and tropospheric trace gas composition. He's a member of NASA's Health and Air Quality Applied Sciences Team, which facilitates the use of NASA satellite data by the health and air quality communities. He is also the Assistant Lab Chief for the ACDL.

Research Interests

Bryan's General Research Interests

Solar System: Atmospheres

• Constraining tropospheric OH with satellite observations of its drivers.

• Simulating atmospheric methane to understand causes of variations and trends.

• Observing systems for OH, methane, and the Arctic-boreal zone.

• The long-range transport of anthropogenic and biomass burning pollution.

• Air quality as observed from space-borne instruments.

• Observational and modeled trends in tropospheric composition.

• Past, present, and future biomass burning trends.

• Application of satellite data for estimates of tropospheric composition and emissions.

• Interpretation of satellite data with chemical transport models.


Current Projects

NASA Aura Satellite Mission


The Aura mission, launched July 15, 2004, obtains composition measurements in the troposphere, stratosphere, and mesosphere. Aura instruments continue the record of total column ozone measurements begun in late 1979 by Nimbus 7 Total Ozone Mapping Spectrometer (TOMS) and provide vertical profiles of many constituents that are crucial for monitoring the health of the protective ozone layer, following NASA's charter under the 1977 Congressional Clean Air Act. These measurements expand our knowledge of the processes that control the size and depth of the Antarctic ozone hole, the unexpected continental scale ozone depletion that was discovered in 1985. The ozone hole exemplifies the global and detrimental impact of human activity on Earth's atmosphere and remains an annual feature of the southern stratosphere even as anthropogenic ozone depleting substances (ODSs) slowly decrease. Aura's global measurements reveal the intricacies of the interactions between chemical and dynamical processes that impact the Antarctic ozone hole and lead to significant northern polar ozone depletion during cold winters as in 2011 and 2016. These measurements inform atmospheric models that project the stratospheric state as the ODSs decrease in response to the Montreal Protocol and its amendments, without which worldwide thinning of the ozone layer and devastating increases in the UV radiation reaching Earth's surface would have occurred (i.e., the "world avoided''; Newman et al., 2009).

Aura measurements in the lower atmosphere are similarly transformative. The period since Aura's launch has been marked by complex changes in worldwide anthropogenic pollution emissions; such changes are in some cases the result of unique and unexpected events and have been quantified at sub-urban and even power-plant scales using Aura data. Models and observations are used together to quantify the impact of emissions changes on countries downwind of emitters. The Aura record encompasses natural variations, such as the strong 2015 El Nino that led to a severe Indonesian fire season. Each such event carries implications for the world economy and for society. Aura makes substantial contributions to climate science through its measurements of parameters such as water vapor, ozone, solar irradiance, and aerosols.

For more on Aura, please visit



Research Physical Scientist

NASA - Greenbelt, MD

January 2009 - Present

Assistant, Associate, to Senior Research Scientist

University of Maryland Baltimore County - Maryland

January 2004 - December 2008

Research Associate

Swiss Institute of Technology - Lausanne, Switzerland

October 2001 - October 2003

Postdoctoral Fellow to Research Associate

Harvard University - Cambridge, MA

October 1997 - October 2001

Graduate Research Assistant

Georgia Institute of Technology - Atlanta, GA

September 1991 - September 1997

Chemistry Lab Technician

Georgia Tech Research Institute - Atlanta, GA

March 1990 - December 1993

Environmental Field Technician

Engineering Science, Inc. - Atlanta, GA

March 1988 - March 1990

Chemistry Lab Technician

Federal Paper Board - Augusta, GA

March 1987 - December 1987


Georgia Institute of Technology, Atlanta, GA

Ph.D. Earth and Atmospheric Sciences (1997)
Thesis The Effects of Urban Ozone Control Strategies on Northern Hemispheric, Midlatitude Tropospheric Ozone
Advisor William Chameides
Minor Environmental Public Policy

M.S. Earth and Atmospheric Sciences (1993)

B.S. Chemistry (1991)

Professional Service

  • Co-editor for the scientific journal, Atmospheric Chemistry and Physics (ACP) (2008-present).
  • Served on the subpanel, Weather and Air Quality, of the 2017 National Academies of Sciences, Engineering, and Medicine Decadal Survey for Earth Science and Applications from Space.
  • Served as co-chair (2016-2018) of the International IGAC/SPARC Chemistry Climate Model Initiative (CCMI).




2024. "Trends and Interannual Variability of the Hydroxyl Radical in the Remote Tropics During Boreal Autumn Inferred From Satellite Proxy Data." Geophysical Research Letters 51 (8): [10.1029/2024gl108531] [Journal Article/Letter]

2023. "An observation-based, reduced-form model for oxidation in the remote marine troposphere." Proceedings of the National Academy of Sciences 120 (34): [10.1073/pnas.2209735120] [Journal Article/Letter]

2023. "Technical note: Constraining the hydroxyl (OH) radical in the tropics with satellite observations of its drivers – first steps toward assessing the feasibility of a global observation strategy." Atmospheric Chemistry and Physics 23 (11): 6319-6338 [10.5194/acp-23-6319-2023] [Journal Article/Letter]

2022. "Satellite Data Applications for Sustainable Energy Transitions." Frontiers in Sustainability 3 [10.3389/frsus.2022.910924] [Journal Article/Letter]

2022. "A machine learning methodology for the generation of a parameterization of the hydroxyl radical." Geoscientific Model Development 15 (16): 6341-6358 [10.5194/gmd-15-6341-2022] [Journal Article/Letter]

2022. "Communicating respiratory health risk among children using a global air quality index." Environment International 159 107023 [10.1016/j.envint.2021.107023] [Journal Article/Letter]

2021. "Augmenting the Standard Operating Procedures of Health and Air Quality Stakeholders With NASA Resources." GeoHealth 5 (9): [10.1029/2021gh000451] [Journal Article/Letter]

2021. "Satellite Monitoring for Air Quality and Health." Annual Review of Biomedical Data Science 4 (1): 417-447 [10.1146/annurev-biodatasci-110920-093120] [Journal Article/Letter]

2021. "Spatial and temporal variability in the hydroxyl (OH) radical: understanding the role of large-scale climate features and their influence on OH through its dynamical and photochemical drivers." Atmospheric Chemistry and Physics 21 (8): 6481-6508 [10.5194/acp-21-6481-2021] [Journal Article/Letter]

2021. "Description of the NASA GEOS Composition Forecast Modeling System GEOS‐CF v1.0." Journal of Advances in Modeling Earth Systems 13 (4): [10.1029/2020ms002413] [Journal Article/Letter]

2020. "Strong sensitivity of the isotopic composition of methane to the plausible range of tropospheric chlorine." Atmospheric Chemistry and Physics 20 (14): 8405-8419 [10.5194/acp-20-8405-2020] [Journal Article/Letter]

2020. "Space‐Based Observations for Understanding Changes in the Arctic‐Boreal Zone." Reviews of Geophysics 58 (1): 2019RG000652 [10.1029/2019rg000652] [Journal Article/Letter]

2020. "A machine learning examination of hydroxyl radical differences among model simulations for CCMI-1." Atmospheric Chemistry and Physics 20 (3): 1341-1361 [10.5194/acp-20-1341-2020] [Journal Article/Letter]

2020. "A methodology to constrain carbon dioxide emissions from coal-fired power plants using satellite observations of co-emitted nitrogen dioxide." Atmospheric Chemistry and Physics 20 99-116 [10.5194/acp-20-99-2020] [Journal Article/Letter]

2019. "Exploiting OMI NO2 satellite observations to infer fossil-fuel CO2 emissions from U.S. megacities." Science of The Total Environment 695 133805 [10.1016/j.scitotenv.2019.133805] [Journal Article/Letter]

2019. "The benefits of lower ozone due to air pollution emissions reductions (2002-2011) in the Eastern US during extreme heat." Journal of the Air & Waste Management Association [10.1080/10962247.2019.1694089] [Journal Article/Letter]

2019. "Air Pollution Monitoring for Health Research and Patient Care. An Official American Thoracic Society Workshop Report." Annals of the American Thoracic Society 16 (10): 1207-1214 [10.1513/annalsats.201906-477st] [Journal Article/Letter]

2019. "Potential improvements in global carbon flux estimates from a network of laser heterodyne radiometer measurements of column carbon dioxide." Atmospheric Measurement Techniques 12 (4): 2579-2594 [10.5194/amt-12-2579-2019] [Journal Article/Letter]

2019. "Earth Observations and Integrative Models in Support of Food and Water Security." Remote Sensing in Earth Systems Sciences [10.1007/s41976-019-0008-6] [Journal Article/Letter]

2018. "Peroxy acetyl nitrate (PAN) measurements at northern midlatitude mountain sites in April: a constraint on continental source–receptor relationships." Atmospheric Chemistry and Physics 18 (20): 15345-15361 [10.5194/acp-18-15345-2018] [Journal Article/Letter]

2018. "Estimates of the Global Burden of Ambient PM2.5, Ozone, and NO2 on Asthma Incidence and Emergency Room Visits." Environmental Health Perspectives 126 (10): 107004 [10.1289/ehp3766] [Journal Article/Letter]

2018. "The Ozone Monitoring Instrument: overview of 14 years in space." Atmospheric Chemistry and Physics 18 (8): 5699-5745 [10.5194/acp-18-5699-2018] [Journal Article/Letter]

2018. "Satellites See the World’s Atmosphere." Meteorological Monographs 59 4.1-4.53 [10.1175/amsmonographs-d-18-0009.1] [Journal Article/Letter]

2017. "Chemical Mechanisms and Their Applications in the Goddard Earth Observing System (GEOS) Earth System Model." Journal of Advances in Modeling Earth Systems [10.1002/2017ms001011] [Journal Article/Letter]

2017. "A decade of changes in nitrogen oxides over regions of oil and natural gas activity in the United States." Elem Sci Anth 5 (0): 76 [10.1525/elementa.259] [Journal Article/Letter]

2017. "Evaluating a space-based indicator of surface ozone-NOx-VOC sensitivity over mid-latitude source regions and application to decadal trends." Journal of Geophysical Research: Atmospheres [10.1002/2017jd026720] [Journal Article/Letter]

2017. "Stratospheric intrusion-influenced ozone air quality exceedances investigated in the NASA MERRA-2 Reanalysis." Geophysical Research Letters 44 (10): 691–10,701 [10.1002/2017gl074532] [Journal Article/Letter]

2017. "Global O3–CO correlations in a chemistry and transport model during July–August: evaluation with TES satellite observations and sensitivity to input meteorological data and emissions." Atmospheric Chemistry and Physics 17 (13): 8429-8452 [10.5194/acp-17-8429-2017] [Journal Article/Letter]

2016. "Interpreting space-based trends in carbon monoxide with multiple models." Atmos. Chem. Phys. 16 (11): 7285-7294 [10.5194/acp-16-7285-2016] [Journal Article/Letter]

2016. "An observationally constrained evaluation of the oxidative capacity in the tropical western Pacific troposphere." J. Geophys. Res. Atmos. 121 (12): 7461–7488 [10.1002/2016jd025067] [Journal Article/Letter]

2016. "Frequency and impact of summertime stratospheric intrusions over Maryland during DISCOVER-AQ (2011): New evidence from NASA's GEOS-5 simulations." J. Geophys. Res. Atmos. [10.1002/2015jd024052] [Journal Article/Letter]

2016. "Aura OMI observations of regional SO2 and NO2 pollution changes from 2005 to 2015." Atmos. Chem. Phys. 16 (7): 4605-4629 [10.5194/acp-16-4605-2016] [Journal Article/Letter]

2016. "The description and validation of the computationally Efficient CH4–CO–OH (ECCOHv1.01) chemistry module for 3-D model applications ." Geoscientific Model Development 9 799-822 [doi:10.5194/gmd-9-799-2016] [Journal Article/Letter]

2016. " A space-based, high-resolution view of notable changes in urban NO x pollution around the world (2005-2014) ." J. Geophys. Res. Atmos. 121 (2): 976–996 [10.1002/2015jd024121] [Journal Article/Letter]

2015. "Implications of carbon monoxide bias for methane lifetime and atmospheric composition in chemistry climate models." Atmospheric Chemistry and Physics 15 11789–11805 [10.5194/acp-15-11789-2015] [Journal Article/Letter]

2015. "Aura OMI observations of regional SO2 and NO2 pollution changes from 2005 to 2014." Atmos. Chem. Phys. 16 4605-4629 [10.5194/acp-16-4605-2016] [Journal Article/Letter]

2015. "Spatial and temporal variability of trace gas columns derived from WRF/Chem regional model output: Planning for geostationary observations of atmospheric composition." Atmospheric Environment 118 28–44 [10.1016/j.atmosenv.2015.07.024] [Journal Article/Letter]

2015. "Emissions of nitrogen oxides from US urban areas: estimation from Ozone Monitoring Instrument retrievals for 2005–2014 ." Atmos. Chem. Phys. 15 10367-10383 [10.5194/acp-15-10367-2015] [Journal Article/Letter]

2015. "Estimates of power plant NOx emissions and lifetimes from OMI NO2 satellite retrievals." Atmospheric Environment 116 1-11 [10.1016/j.atmosenv.2015.05.056] [Journal Article/Letter]

2015. "The POLARCAT Model Intercomparison Project (POLMIP): overview and evaluation with observations ." Atmos. Chem. Phys. 15 6721-6744 [10.5194/acp-15-6721-2015] [Journal Article/Letter]

2015. "U.S. NO2 trends (2005–2013): EPA Air Quality System (AQS) data versus improved observations from the Ozone Monitoring Instrument (OMI)." Atmos. Env. 110 130-143 [10.1016/j.atmosenv.2015.03.055] [Journal Article/Letter]

2015. "Tropospheric ozone variability in the tropics from ENSO to MJO and shorter timescales." Atmos. Chem. Phys. 15 (14): 8037-8049 [10.5194/acp-15-8037-2015] [Journal Article/Letter]

2015. "Multi-model study of chemical and physical controls on transport of anthropogenic and biomass burning pollution to the Arctic." Atmos. Chem. Phys. 15 (6): 3575-3603 [10.5194/acp-15-3575-2015] [Journal Article/Letter]

2015. "Biomass burning influence on high-latitude tropospheric ozone and reactive nitrogen in summer 2008: a multi-model analysis based on POLMIP simulations." Atmos. Chem. Phys. 15 (11): 6047-6068 [10.5194/acp-15-6047-2015] [Journal Article/Letter]

2014. "Model evaluation of methods for estimating surface emissions and chemical lifetimes from satellite data." Atmospheric Environment 98 66–77 [10.1016/j.atmosenv.2014.08.051] [Journal Article/Letter]

2014. "Anthropogenic emissions of highly reactive volatile organic compounds in eastern Texas inferred from oversampling of satellite (OMI) measurements of HCHO columns." Environmental Research Letters 9 (11): 114004 [10.1088/1748-9326/9/11/114004] [Journal Article/Letter]

2014. "First estimates of global free-tropospheric NO2 abundances derived using a cloud-slicing technique applied to satellite observations from the Aura Ozone Monitoring Instrument (OMI)." Atmos. Chem. Phys. 14 (19): 10565-10588 [10.5194/acp-14-10565-2014] [Journal Article/Letter]

2014. "Assessment and applications of NASA ozone data products derived from Aura OMI/MLS satellite measurements in context of the GMI chemical transport model." J. Geophys. Res. Atmos. 119 (9): 5671-5699 [10.1002/2013JD020914] [Journal Article/Letter]

2014. "Satellite data of atmospheric pollution for U.S. air quality applications: Examples of applications, summary of data end-user resources, answers to FAQs, and common mistakes to avoid." Atmospheric Environment 94 647-662 [10.1016/j.atmosenv.2014.05.061] [Journal Article/Letter]

2014. "Using Satellite Observations to Measure." Environmental Manager 64 16-21 [Journal Article/Letter]

2014. "Global carbon monoxide products from combined AIRS, TES and MLS measurements on A-train satellites." Atmos. Chem. Phys. 14 (1): 103-114 [10.5194/acp-14-103-2014] [Journal Article/Letter]

2013. "Emissions estimation from satellite retrievals: A review of current capability." Atmospheric Environment 77 1011-1042 [10.1016/j.atmosenv.2013.05.051] [Journal Article/Letter]

2013. "The observed response of Ozone Monitoring Instrument (OMI) NO2 columns to NOx emission controls on power plants in the United States: 2005–2011." Atmospheric Environment 81 102-111 [10.1016/j.atmosenv.2013.08.068] [Journal Article/Letter]

2012. "Modelling future changes in surface ozone: a parameterized approach." Atmos. Chem. Phys. 12 (4): 2037-2054 [10.5194/acp-12-2037-2012] [Journal Article/Letter]

2012. "The influence of ozone precursor emissions from four world regions on tropospheric composition and radiative climate forcing." J. Geophys. Res. 117 (D7): D07306 [10.1029/2011JD017134] [Journal Article/Letter]

2011. "NASA A-Train and Terra observations of the 2010 Russian wildfires." Atmos. Chem. Phys. 11 (17): 9287-9301 [10.5194/acp-11-9287-2011] [Journal Article/Letter]

2011. "Reactive nitrogen, ozone and ozone production in the Arctic troposphere and the impact of stratosphere-troposphere exchange." Atmos. Chem. Phys. 11 (24): 13181-13199 [10.5194/acp-11-13181-2011] [Journal Article/Letter]

2011. "The unique OMI HCHO/NO2 feature during the 2008 Beijing Olympics: Implications for ozone production sensitivity." Atmospheric Environment 45 (18): 3103-3111 [10.1016/j.atmosenv.2011.03.015] [Journal Article/Letter]

2010. "Application of OMI observations to a space-based indicator of NOx and VOC controls on surface ozone formation." Atmos Environ 44 (18): 2213-2223 [10.1016/j.atmosenv.2010.03.010] [Journal Article/Letter]

2010. "Impact of lightning NO emissions on North American photochemistry as determined using the Global Modeling Initiative (GMI) model." J Geophys Res 115 (D22): D22301 [10.1029/2010JD014062] [Journal Article/Letter]

2010. "Influence of the 2006 Indonesian biomass burning aerosols on tropical dynamics studied with the GEOS-5 AGCM." J Geophys Res 115 (D14): D14121 [10.1029/2009JD013181] [Journal Article/Letter]

2010. "The impact of the 2005 Gulf hurricanes on pollution emissions as inferred from Ozone Monitoring Instrument (OMI) nitrogen dioxide." Atmos Environ 44 (11): 1443-1448 [10.1016/j.atmosenv.2010.01.037] [Journal Article/Letter]

2009. "Multimodel estimates of intercontinental source-receptor relationships for ozone pollution." J. Geophys. Res. 114 (D4): D04301 [10.1029/2008JD010816] [Journal Article/Letter]

2009. "Intercontinental impacts of ozone pollution on human mortality." Environ Sci Technol 43 (17): 6482-6487 [10.1021/es900518z] [Journal Article/Letter]

2009. "Effects of the 2006 El Niño on tropospheric ozone and carbon monoxide: implications for dynamics and biomass burning." Atmos. Chem. Phys. 9 (13): 4239-4249 [10.5194/acp-9-4239-2009] [Journal Article/Letter]

2009. "The influence of foreign vs. North American emissions on surface ozone in the U.S." Atmos Chem Phys 9 (14): 5027-5042 [10.5194/acp-9-5027-2009] [Journal Article/Letter]

2009. "Vegetation fire emissions and their impact on air pollution and climate." Atmospheric Environment 43 (1): 107-116 [10.1016/j.atmosenv.2008.09.047] [Journal Article/Letter]

2009. "The governing processes and timescales of stratosphere-to-troposphere transport and its contribution to ozone in the Arctic troposphere." Atmos. Chem. Phys. 9 (9): 3011-3025 [10.5194/acp-9-3011-2009] [Journal Article/Letter]

2009. "Temperature dependence of factors controlling isoprene emissions." Geophysical Research Letters 36 (5): L05813 [10.1029/2008GL037090] [Journal Article/Letter]

2009. "Recent biomass burning in the tropics and related changes in tropospheric ozone." Geophysical Research Letters 36 (15): L15819 [10.1029/2009GL039303] [Journal Article/Letter]

2009. "Chemical nonlinearities in relating intercontinental ozone pollution to anthropogenic emissions." Geophysical Research Letters 36 (5): L05806 [10.1029/2008GL036607] [Journal Article/Letter]

2009. "Sensitivity of photolysis frequencies and key tropospheric oxidants in a global model to cloud vertical distributions and optical properties." J. Geophys. Res. 114 (D10): D10305 [10.1029/2008JD011503] [Journal Article/Letter]

2008. "A multi-model assessment of pollution transport to the Arctic." Atmos. Chem. Phys. 8 (17): 5353-5372 [10.5194/acp-8-5353-2008] [Journal Article/Letter]

2008. "Model analysis of the factors regulating the trends and variability of carbon monoxide between 1988 and 1997." Atmos. Chem. Phys. 8 (24): 7389-7403 [10.5194/acp-8-7389-2008] [Journal Article/Letter]

2008. "The influence of European pollution on ozone in the Near East and northern Africa." Atmos. Chem. Phys. 8 (8): 2267-2283 [10.5194/acp-8-2267-2008] [Journal Article/Letter]

2008. "A multi-model study of the hemispheric transport and deposition of oxidised nitrogen." Geophysical Research Letters 35 (17): L17815 [10.1029/2008GL035389] [Journal Article/Letter]

2008. "Model analysis of the factors regulating the trends of carbon monoxide, 1988-1997." Atmos Chem Phys 8 7389-7403 [Journal Article/Letter]

2007. "A trajectory-based estimate of the tropospheric ozone column using the residual method." Journal of Geophysical Research 112 (D24): D24S49 [10.1029/2007jd008773] [Journal Article/Letter]

2007. "An Evaluation of the Impact of Lightning NO Emissions in the GMI Model on Upper Tropospheric Chemistry in the Tropics using SHADOZ data." AGU Fall Meeting Abstracts (A21D-0737): D737 [Other]

2007. "Model study of the cross-tropopause transport of biomass burning pollution." Atmos Chem Phys 7 3713-3736 [Journal Article/Letter]

2007. "Observationally derived transport diagnostics for the lowermost stratosphere and their application to the GMI chemistry and transport model." Atmos Chem Phys 7 2435-2445 [Journal Article/Letter]

2007. "The global budget of CO, 1988-1997: source estimates and validation with a global model." J Geophys Res 112 (D22301): [] [Journal Article/Letter]

2006. "The Carbon Monoxide Tape Recorder ." Journal of Geophysical Research 33 [Journal Article/Letter]

2006. "Tropospheric ozone determined from Aura OMI and MLS: Evaluation of measurements and comparison with the Global Modeling Initiative's Chemical Transport Model." J. Geophys. Res. 111 (D19): D19303 [10.1029/2006JD007089] [Journal Article/Letter]

2004. "A 3-D model analysis of the slowdown and interannual variability in the methane growth rate from 1988 to 1997." Global Biogeochem. Cycles 18 (3): GB3011 [10.1029/2003GB002180] [Journal Article/Letter]

2002. "Tropospheric aerosol optical thickness from the GOCART model and comparisons with satellite and sunphotometer measurements." J. Atm. Sci. 59 461-483. [Journal Article/Letter]


2020. "NASA resources to monitor offshore and coastal air quality." Sterling (VA): U.S. Department of the Interior, Bureau of Ocean Energy Management. OCS Study BOEM (2020-046): 32 [] [Report]

2020. "Insights from Space: Satellite Observations of Arctic Change." Eos 101 [10.1029/2020eo136294] [Magazine]