Sciences and Exploration Directorate

Christoph Andrea Keller


Christoph Andrea Keller's Contact Card & Information.
Phone: 301.614.6945
Org Code: 610.1
Mail Code 610.1
Greenbelt, MD 20771


Senior Research Scientist

NASA GMAO / Morgan State University - NASA Goddard Space Flight Center, Greenbelt, Maryland

December 2021 - Present

  • Development and maintenance of the GEOS Composition Forecast System (GEOS-CF)
  • Data assimilation of tropospheric constituents

Scientist / Senior Scientist

NASA GMAO / USRA - NASA Goddard Space Flight Center, Greenbelt, Maryland

January 2016 - November 2021

  • Development of the GEOS Composition Forecast System GEOS-CF
  • Development and maintenance of the GEOS-Chem atmospheric chemistry module within the GEOS Earth System Model.

Research Associate

School of Engineering and Applied Sciences, Harvard University - Cambridge, Massachusetts

February 2012 - January 2016

  • Development of the harmonized emissions component (HEMCO), a stand-alone software component for calculating emissions in global atmospheric models.
  • Coupling of the GEOS-Chem chemical transport model to the GEOS Earth System Model.


  • Ph.D., Atmospheric and Climate Science, EMPA / ETH Zurich (2012)
  • M.Sc., Atmospheric and Climate Science, ETH Zurich (2008)
  • B.Sc., Earth Sciences, ETH Zurich (2006)


2021 ACP Paul Crutzen Publication Award for the outstanding paper "Global Impact of COVID-19 restrictions on the surface concentrations of nitrogen dioxide and ozone"



2024. "Particulate Nitrate Photolysis as a Possible Driver of Rising Tropospheric Ozone." Geophysical Research Letters 51 (5): [10.1029/2023gl107980] [Journal Article/Letter]

2024. "Limitations of XAI methods for process-level understanding in the atmospheric sciences." Artificial Intelligence for the Earth Systems [10.1175/aies-d-23-0045.1] [Journal Article/Letter]

2023. "Public Health Data Applications Using the CDC Tracking Network: Augmenting Environmental Hazard Information With Lower‐Latency NASA Data." GeoHealth 7 (12): [10.1029/2023gh000971] [Journal Article/Letter]

2023. "Using Regionalized Air Quality Model Performance and Bayesian Maximum Entropy data fusion to map global surface ozone concentration." Elem Sci Anth 11 (1): [10.1525/elementa.2022.00025] [Journal Article/Letter]

2023. "Tropospheric ozone data assimilation in the NASA GEOS composition forecast modeling system (GEOS-CF v2.0) using satellite data for ozone vertical profiles (MLS), total ozone columns (OMI), and thermal infrared radiances (AIRS, IASI)." Environmental Research Letters [10.1088/1748-9326/acf0b7] [Journal Article/Letter]

2023. "Application of Satellite‐Based Detections of Arctic Bromine Explosion Events Within GEOS‐Chem." Journal of Advances in Modeling Earth Systems 15 (8): [10.1029/2022ms003465] [Journal Article/Letter]

2023. "Interactive Stratospheric Aerosol Microphysics‐Chemistry Simulations of the 1991 Pinatubo Volcanic Aerosols With Newly Coupled Sectional Aerosol and Stratosphere‐Troposphere Chemistry Modules in the NASA GEOS Chemistry‐Climate Model (CCM)." Journal of Advances in Modeling Earth Systems 15 (8): [10.1029/2022ms003147] [Journal Article/Letter]

2023. "Koopman-inspired approach for identification of exogenous anomalies in nonstationary time-series data." Machine Learning: Science and Technology 4 (2): 025033 [10.1088/2632-2153/acdd50] [Journal Article/Letter]

2022. "Improved advection, resolution, performance, and community access in the new generation (version 13) of the high-performance GEOS-Chem global atmospheric chemistry model (GCHP)." Geoscientific Model Development 15 (23): 8731-8748 [10.5194/gmd-15-8731-2022] [Journal Article/Letter]

2022. "Diesel passenger vehicle shares influenced COVID-19 changes in urban nitrogen dioxide pollution." Environmental Research Letters 17 (7): 074010 [10.1088/1748-9326/ac7659] [Journal Article/Letter]

2022. "Aerosol‐Radiation Interactions in China in Winter: Competing Effects of Reduced Shortwave Radiation and Cloud‐Snowfall‐Albedo Feedbacks Under Rapidly Changing Emissions." Journal of Geophysical Research: Atmospheres 127 (9): [10.1029/2021jd035442] [Journal Article/Letter]

2022. "NASA GEOS Composition Forecast Modeling System GEOS‐CF v1.0: Stratospheric composition." Journal of Advances in Modeling Earth Systems 14 (e2021MS002852): [10.1029/2021ms002852] [Journal Article/Letter]

2022. "Using an Explainable Machine Learning Approach to Characterize Earth System Model Errors: Application of SHAP Analysis to Modeling Lightning Flash Occurrence." Journal of Advances in Modeling Earth Systems [10.1029/2021ms002881] [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]

2022. "Combining Machine Learning and Numerical Simulation for High-Resolution PM2.5 Concentration Forecast." Environmental Science & Technology 56 (3): 1544-1556 [10.1021/acs.est.1c05578] [Journal Article/Letter]

2021. "Global Impact of Lightning‐Produced Oxidants." Geophysical Research Letters 48 (21): [10.1029/2021gl095740] [Journal Article/Letter]

2021. "Grid-stretching capability for the GEOS-Chem 13.0.0 atmospheric chemistry model." Geoscientific Model Development 14 (10): 5977-5997 [10.5194/gmd-14-5977-2021] [Journal Article/Letter]

2021. "Ozone production and precursor emission from wildfires in Africa." Environ. Sci.: Atmos. 1 524-542 [10.1039/d1ea00041a] [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. "Harmonized Emissions Component (HEMCO) 3.0 as a versatile emissions component for atmospheric models: application in the GEOS-Chem, NASA GEOS, WRF-GC, CESM2, NOAA GEFS-Aerosol, and NOAA UFS models." Geoscientific Model Development 14 (9): 5487-5506 [10.5194/gmd-14-5487-2021] [Journal Article/Letter]

2021. "Sub‐City Scale Hourly Air Quality Forecasting by Combining Models, Satellite Observations, and Ground Measurements." Earth and Space Science 8 (7): [10.1029/2021ea001743] [Journal Article/Letter]

2021. "Long-range transport of Siberian biomass burning emissions to North America during FIREX-AQ." Atmospheric Environment 252 118241 [10.1016/j.atmosenv.2021.118241] [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]

2021. "Global impact of COVID-19 restrictions on the surface concentrations of nitrogen dioxide and ozone." Atmospheric Chemistry and Physics 21 (5): 3555-3592 [10.5194/acp-21-3555-2021] [Journal Article/Letter]

2021. "Mapping Yearly Fine Resolution Global Surface Ozone through the Bayesian Maximum Entropy Data Fusion of Observations and Model Output for 1990–2017." Environmental Science & Technology acs.est.0c07742 [10.1021/acs.est.0c07742] [Journal Article/Letter]

2020. "Current and future global climate impacts resulting from COVID-19." Nature Climate Change [10.1038/s41558-020-0883-0] [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. "WRF-GC (v1.0): online coupling of WRF (v3.9.1.1) and GEOS-Chem (v12.2.1) for regional atmospheric chemistry modeling – Part 1: Description of the one-way model." Geoscientific Model Development 13 (7): 3241-3265 [10.5194/gmd-13-3241-2020] [Journal Article/Letter]

2020. "Global high-resolution emissions of soil NOx, sea salt aerosols, and biogenic volatile organic compounds." Scientific Data 7 (1): 148 [10.1038/s41597-020-0488-5] [Journal Article/Letter]

2019. "Scalable diagnostics for global atmospheric chemistry using Ristretto library (version 1.0)." Geoscientific Model Development 12 (4): 1525-1539 [10.5194/gmd-12-1525-2019] [Journal Article/Letter]

2019. "Application of random forest regression to the calculation of gas-phase chemistry within the GEOS-Chem chemistry model v10." Geoscientific Model Development 12 (3): 1209-1225 [10.5194/gmd-12-1209-2019] [Journal Article/Letter]

2019. "A new method (M3Fusion-v1) for combining observations and multiple model output for an improved estimate of the global surface ozone distribution." Geoscientific Model Development 12 (3): 955-978 [10.5194/gmd-12-955-2019] [Journal Article/Letter]

2018. "Global simulation of tropospheric chemistry at 12.5 km resolution: performance and evaluation of the GEOS-Chem chemical module (v10-1) within the NASA GEOS Earth system model (GEOS-5 ESM)." Geoscientific Model Development 11 (11): 4603-4620 [10.5194/gmd-11-4603-2018] [Journal Article/Letter]

2018. "Global Sources of Fine Particulate Matter: Interpretation of PM2.5 Chemical Composition Observed by SPARTAN using a Global Chemical Transport Model." Environmental Science & Technology 52 (20): acs.est.8b01658 [10.1021/acs.est.8b01658] [Journal Article/Letter]

2018. "GEOS-Chem High Performance (GCHP v11-02c): a next-generation implementation of the GEOS-Chem chemical transport model for massively parallel applications." Geoscientific Model Development 11 (7): 2941-2953 [10.5194/gmd-11-2941-2018] [Journal Article/Letter]

2018. "Errors and improvements in the use of archived meteorological data for chemical transport modeling: an analysis using GEOS-Chem v11-01 driven by GEOS-5 meteorology." Geoscientific Model Development 11 (1): 305-319 [10.5194/gmd-11-305-2018] [Journal Article/Letter]

2017. "Impact of Southeast Asian smoke on aerosol properties in Southwest China: First comparison of model simulations with satellite and ground observations." Journal of Geophysical Research: Atmospheres 122 (7): 3904-3919 [10.1002/2016jd025793] [Journal Article/Letter]

2015. "Development of a grid-independent GEOS-Chem chemical transport model (v9-02) as an atmospheric chemistry module for Earth system models." Geosci. Model Dev. 8 (3): 595-602 [10.5194/gmd-8-595-2015] [Journal Article/Letter]

2014. "HEMCO v1.0: a versatile, ESMF-compliant component for calculating emissions in atmospheric models." Geoscientific Model Development 7 (4): 1409-1417 [10.5194/gmd-7-1409-2014] [Journal Article/Letter]


2022. "File Specification for GEOS-CF Products." GMAO Office Note No. 17 (Version 1.2), 53pp, available from [Other]

2021. "File Specification for MERRA-2 Country-Level Surface PM2.5 Monthly Mean Products." GMAO Office Note No. 20 (Version 1.0): 10 [Full Text] [Other]

2020. "File Specification for GEOS-CF Products." GMAO Office Note No. 17 (Version 1.1), 37pp, available from [Other]

2019. "File Specification for GEOS-CF Products." GMAO Office Note No. 17 (Version 1.0), 32pp, available from [Other]