Sciences and Exploration Directorate

Junhua Liu


Junhua Liu's Contact Card & Information.
Phone: 301.614.5739
Org Code: 614
Mail Code 614
Greenbelt, MD 20771

Brief Bio

Dr. Junhua Liu joined USRA/GESTAR in Nov 2013. Her current research focuses on quantifying the factors controlling the observed interannual variations and trends in tropospheric O3 and precursors during the past 20 years using an ensemble of satellite, aircraft, surface observations and GMI model, and investigating their interaction with the Earth’s climate. Prior to joining USRA, GSFC, Junhua worked as post-doctoral fellow and research associate at Harvard University on seasonal and interannual variations of carbon monoxide (CO) in the tropical troposphere and lower stratosphere and its inference for vertical transport using Aura satellite data and the GEOS-Chem model.

Research Interests

Dr. Liu's main research interests lie in understanding the processes affecting atmospheric composition in the troposphere and lower stratosphere, specifically the sources, chemical evolution and transport pathways.

Earth Science: Atmospheric Chemistry


Current Projects

Atmospheric Composition Analysis:

Using global chemistry transport model (CTM) and chemistry climate models (CCM) along with in-situ and satellite measurements to understand the global distribution of atmospheric trace gases as well as their trends and interannual variations.

My ongoing work is using a high-resolution (~50km) GEOS-5 Replay simulation with the Global Modeling Initiative (GMI) chemical mechanism, and its various tracer diagnostics to exam the spatial distribution and vertical extent of impacts of stratosphere – troposphere exchange (STE) on tropospheric ozone. Furthermore, quantifying the contributions of stratospheric and anthropogenic effects on tropospheric ozone radiative forcing and on regional air quality. Understanding how tropospheric ozone and associated radiative forcing will change in the future and investigating their interactions with Earth’s climate.

Observational-Based Atmospheric Model Evaluation:

Participating in the development of the Global Modeling and Assimilation Office (GMAO) composition forecasting system in GEOS-5, by providing ozone, PM2.5, NOX evaluations and building up benchmark plots of model outputs. Developing an observational-based evaluation package for the long-term CCM and CTM simulations.

Field Mission Support and Data Analysis:

Participating in the modeling effort for the Atmospheric Tomography Mission (ATom). Providing chemistry forecasting with GEOS-5 model for the missions. Using ATom CO, Ozone observations and model simulations to examine the spatial and temporal representativeness of ATom transects.


Senior Scientist

GESTAR II, MSU, NASA/GSFC - code 614- Greenbelt

December 2021 - Present


USRA, NASA/GSFC, code 614 - Greenbelt

October 2018 - Present

Scientist II

USRA - NASA/GSFC, code 614

January 2017 - September 2018

Scientist I

USRA - NASA/GSFC, code 614

November 2013 - December 2016

Research Associate

Atmospheric Chemistry Modeling Group, Harvard University - Cambridge MA 02138

July 2011 - October 2013

Postdoc Research Fellow

Atmospheric Chemistry Modeling Group, Harvard University - Cambridge MA

July 2008 - July 2011


Ph.D.(2008), Climatology/Paleoclimatology, Duke University, Durham, NC

B.S. (2002), Environmental Geochemistry, University of Science and Technology of China (USTC), Hefei, Anhui, China

Professional Service

Reviewer for several scientific journals including: Journal of Geophysical Research, Atmospheric Chemistry and Physics, Atmospheric Environment, and Geoscitific Model Development.


Quantifying the effects of STE on tropospheric ozone interannual variability and trends, radiative forcing, and air quality - NASA ROSES (NNH16ZDA001N-ACMAP) - Awarded: 2017-01-09

Dates: 2017-03-01  - 2020-02-29

Coverage: 0.5

Impact of meteorology and emissions on the interannual variations and trends of tropospheric ozone using the Global Model Initiative Combo model - NASA ROSES - Awarded: 2013-03-01

Dates: 2013-11-01  - 2016-10-31

Coverage: 1.0

The very-short-lived halogens (chlorine & bromine) in GEOSCCM-GMI and their impacts on key chemical and climate constituents in the atmosphere - NASA ROSES - Awarded: 2021-03-01

Selected Publications


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. "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. "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. "Multidecadal increases in global tropospheric ozone derived from ozonesonde and surface site observations: can models reproduce ozone trends?." Atmospheric Chemistry and Physics 22 (22): 14751-14782 [10.5194/acp-22-14751-2022] [Journal Article/Letter]

2022. "Change in Tropospheric Ozone in the Recent Decades and Its Contribution to Global Total Ozone." Journal of Geophysical Research: Atmospheres 127 (22): [10.1029/2022jd037170] [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. "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. "The NASA Atmospheric Tomography (ATom) Mission: Imaging the Chemistry of the Global Atmosphere." Bulletin of the American Meteorological Society 103 (3): E761-E790 [10.1175/bams-d-20-0315.1] [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. "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. "Stratospheric impact on the Northern Hemisphere winter and spring ozone interannual variability in the troposphere." Atmospheric Chemistry and Physics 20 (11): 6417-6433 [10.5194/acp-20-6417-2020] [Journal Article/Letter]

2019. "The ENSO and QBO Impact on Ozone Variability and Stratosphere‐Troposphere Exchange Relative to the Subtropical Jets." Journal of Geophysical Research: Atmospheres 2019JD030435 [10.1029/2019jd030435] [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]

2019. "Global changes in the diurnal cycle of surface ozone." Atmospheric Environment 199 323-333 [10.1016/j.atmosenv.2018.11.028] [Journal Article/Letter]

2018. "Forecasting carbon monoxide on a global scale for the ATom-1 aircraft mission: insights from airborne and satellite observations and modeling." Atmospheric Chemistry and Physics 18 (15): 10955-10971 [10.5194/acp-18-10955-2018] [Journal Article/Letter]

2017. "A cloud-ozone data product from Aura OMI and MLS satellite measurements." Atmospheric Measurement Techniques 10 (11): 4067-4078 [10.5194/amt-10-4067-2017] [Journal Article/Letter]

2017. "Global atmospheric chemistry – which air matters." Atmospheric Chemistry and Physics 17 (14): 9081-9102 [10.5194/acp-17-9081-2017] [Journal Article/Letter]

2017. "Causes of interannual variability over the southern hemispheric tropospheric ozone maximum." Atmospheric Chemistry and Physics 17 (5): 3279-3299 [10.5194/acp-17-3279-2017] [Journal Article/Letter]

2016. "Origins of tropospheric ozone interannual variation over Réunion: A model investigation." J. Geophys. Res. Atmos. 121 (1): 521 - 537 [10.1002/ 2015JD023981] [Journal Article/Letter]

2014. "Recent global temperature “plateau” in the context of a new proxy reconstruction." Earth's Future 2 (5): 281-294 [10.1002/2013EF000216] [Journal Article/Letter]

2013. "Transport analysis and source attribution of seasonal and interannual variability of CO in the tropical upper troposphere and lower stratosphere,." Atmos. Chem. Phys. 13 129-146 [10.5194/acp-13-129-2013] [Journal Article/Letter]

2010. "Analysis of CO in the tropical troposphere using Aura satellite data and the GEOS-Chem model: insights into transport characteristics of the GEOS meteorological products." Atmos. Chem. Phys. 10 12207–12232 [10.5194/acp-10-12207-2010] [Journal Article/Letter]

2007. "Health Effects of Arsenic, Fluorine, and Selenium from Indoor Burning of Chinese Coal." Reviews of Environmental Contamination and Toxicology 89-106 [10.1007/978-0-387-35368-5_4] [Article in Book]

2005. "Meta-analysis of tropical surface temperatures during the Last Glacial Maximum." Geophys. Res. Lett 52 (5): [10.1029/2004GL021217] [Journal Article/Letter]

. "Density dependence and population growth: Evaluating classical and Bayesian approaches to parameter estimation and model selection." Statistical computation for environmental sci. in R [Article in Book]