About

Xiaohong Liu is a Professor in the Department of Atmospheric Sciences at Texas A&M University, holding the Reta A. Haynes Chair in Geosciences. His research interests encompass atmospheric aerosols and chemistry, cloud microphysics with a focus on aerosol-cloud interactions, model development and evaluation, and climate modeling. Dr. Liu has extensively studied the life cycles of atmospheric aerosols, including their emission, chemistry, transport, and removal processes, utilizing global and regional models such as CESM, E3SM, and WRF-Chem to investigate their radiative forcings and impacts on climate. His work in cloud microphysics involves examining processes like droplet activation, ice nucleation, and the Bergeron-Findeisen process, particularly in mixed-phase and ice clouds. He has investigated how biomass burning aerosols and mineral dust interact with clouds over different regions, validated through remote sensing and in situ observations. Dr. Liu has contributed significantly to model development, being part of the development teams for CESM and E3SM, including schemes of ice nucleation and aerosol modules, and has participated in IPCC assessments. His climate modeling research explores the effects of aerosols on clouds and hydrological cycles over various regions, including the Tibetan Plateau and North Africa, providing insights into regional climate impacts and future warming scenarios.

Research topics

• Geology
• Atmospheric sciences
• Meteorology
• Environmental science
• Climatology
• Geography
• Oceanography
• Materials science
• Physics
• Chemistry
• Mineralogy
• Optics
• Ecology
• Remote sensing

Selected publications

• Biomass burning aerosols in most climate models are too absorbing

  Nature Communications · 2021 · 219 citations

  • Atmospheric sciences
  • Environmental science
  • Climatology

  (South America/Temperate). Our findings suggest that current modeled BB contributes less to warming than previously thought, largely due to treatments of aerosol mixing state.

  DOI

• Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA)

  Bulletin of the American Meteorological Society · 2021 · 142 citations

  • Environmental science
  • Climatology
  • Atmospheric sciences

  Abstract With their extensive coverage, marine low clouds greatly impact global climate. Presently, marine low clouds are poorly represented in global climate models, and the response of marine low clouds to changes in atmospheric greenhouse gases and aerosols remains the major source of uncertainty in climate simulations. The eastern North Atlantic (ENA) is a region of persistent but diverse subtropical marine boundary layer clouds, whose albedo and precipitation are highly susceptible to perturbations in aerosol properties. In addition, the ENA is periodically impacted by continental aerosols, making it an excellent location to study the cloud condensation nuclei (CCN) budget in a remote marine region periodically perturbed by anthropogenic emissions, and to investigate the impacts of long-range transport of aerosols on remote marine clouds. The Aerosol and Cloud Experiments in Eastern North Atlantic (ACE-ENA) campaign was motivated by the need of comprehensive in situ measurements for improving the understanding of marine boundary layer CCN budget, cloud and drizzle microphysics, and the impact of aerosol on marine low cloud and precipitation. The airborne deployments took place from 21 June to 20 July 2017 and from 15 January to 18 February 2018 in the Azores. The flights were designed to maximize the synergy between in situ airborne measurements and ongoing long-term observations at a ground site. Here we present measurements, observation strategy, meteorological conditions during the campaign, and preliminary findings. Finally, we discuss future analyses and modeling studies that improve the understanding and representation of marine boundary layer aerosols, clouds, precipitation, and the interactions among them.

  PublisherOA PDFDOI

• Aerosol–Ice Formation Closure: A Southern Great Plains Field Campaign

  Bulletin of the American Meteorological Society · 2021 · 77 citations

  Senior authorCorresponding
  • Environmental science
  • Atmospheric sciences
  • Meteorology

  Abstract Prediction of ice formation in clouds presents one of the grand challenges in the atmospheric sciences. Immersion freezing initiated by ice-nucleating particles (INPs) is the dominant pathway of primary ice crystal formation in mixed-phase clouds, where supercooled water droplets and ice crystals coexist, with important implications for the hydrological cycle and climate. However, derivation of INP number concentrations from an ambient aerosol population in cloud-resolving and climate models remains highly uncertain. We conducted an aerosol–ice formation closure pilot study using a field-observational approach to evaluate the predictive capability of immersion freezing INPs. The closure study relies on collocated measurements of the ambient size-resolved and single-particle composition and INP number concentrations. The acquired particle data serve as input in several immersion freezing parameterizations, which are employed in cloud-resolving and climate models, for prediction of INP number concentrations. We discuss in detail one closure case study in which a front passed through the measurement site, resulting in a change of ambient particle and INP populations. We achieved closure in some circumstances within uncertainties, but we emphasize the need for freezing parameterization of potentially missing INP types and evaluation of the choice of parameterization to be employed. Overall, this closure pilot study aims to assess the level of parameter details and measurement strategies needed to achieve aerosol–ice formation closure. The closure approach is designed to accurately guide immersion freezing schemes in models, and ultimately identify the leading causes for climate model bias in INP predictions.

  DOI

• The global dust cycle and uncertainty in CMIP5 (Coupled Model Intercomparison Project phase 5) models

  Atmospheric chemistry and physics · 2020 · 136 citations

  Senior authorCorresponding
  • Environmental science
  • Atmospheric sciences
  • Climatology

  Abstract. The dust cycle is an important component of the Earth system and has been implemented in climate models and Earth system models (ESMs). An assessment of the dust cycle in these models is vital to address their strengths and weaknesses in simulating dust aerosol and its interactions with the Earth system and enhance the future model developments. This study presents a comprehensive evaluation of the global dust cycle in 15 models participating in the fifth phase of the Coupled Model Intercomparison Project (CMIP5). The various models are compared with each other and with an aerosol reanalysis as well as station observations. The results show that the global dust emission in these models varies by a factor of 4–5 for the same size range. The models generally agree with each other and observations in reproducing the “dust belt”, which extends from North Africa, the Middle East, Central and South Asia to East Asia, although they differ greatly in the spatial extent of this dust belt. The models also differ in other dust source regions such as North America and Australia. We suggest that the coupling of dust emission with dynamic vegetation can enlarge the range of simulated dust emission. For the removal process, all the models estimate that wet deposition is smaller than dry deposition and wet deposition accounts for 12 %–39 % of total deposition. The models also estimate that most (77 %–91 %) dust particles are deposited onto continents and 9 %–23 % of dust particles are deposited into oceans. Compared to the observations, most models reproduce the dust deposition and dust concentrations within a factor of 10 at most stations, but larger biases by more than a factor of 10 are also noted at specific regions and for certain models. These results highlight the need for further improvements of the dust cycle especially on dust emission in climate models.

  DOI

• Description and Climate Simulation Performance of CAS‐ESM Version 2

  Journal of Advances in Modeling Earth Systems · 2020 · 138 citations

  • Climatology
  • Environmental science
  • Atmospheric sciences

  Abstract The second version of Chinese Academy of Sciences Earth System Model (CAS‐ESM 2) is described with emphasis on the development process, strength and weakness, and climate sensitivities in simulations of the Coupled Model Intercomparison Project (CMIP6) DECK experiments. CAS‐ESM 2 was built as a numerical model to simulate both the physical climate system as well as atmospheric chemistry and carbon cycle. It is a newcomer in the international modeling community to provide sufficiently independent solutions of climate simulations from those of other models. Performances of the model in simulating the basic states of the radiation budget of the atmosphere and ocean, precipitation, circulations, variabilities, and the twentieth century warming are presented. Model biases and their possible causes are discussed. Strength includes horizontal heat transport in the atmosphere and oceans, vertical profile of the Atlantic Meridional Overturning Circulation; weakness includes the double intertropical convergence zone (ITCZ) and stronger amplitude of the El Niño–Southern Oscillation (ENSO) that are also common in many other models. The simulated the twentieth century warming shares a similar discrepancy with observations as in several other models—less warming in the 1920s and stronger cooling in the 1960s than in observation—at the time when there was a steep increase of anthropogenic aerosols. As a result, the twentieth century warming is about 60% of the observed warming despite that the model simulated a similar slope of warming trend after 1980 to observation. The model has an equilibrium climate sensitivity of 3.4 K with a positive cloud feedback from the shortwave radiation.

  DOI

• Understanding processes that control dust spatial distributions with global climate models and satellite observations

  Atmospheric chemistry and physics · 2020 · 113 citations

  • Environmental science
  • Atmospheric sciences
  • Remote sensing

  Abstract. Dust aerosol is important in modulating the climate system at local and global scales, yet its spatiotemporal distributions simulated by global climate models (GCMs) are highly uncertain. In this study, we evaluate the spatiotemporal variations of dust extinction profiles and dust optical depth (DOD) simulated by the Community Earth System Model version 1 (CESM1) and version 2 (CESM2), the Energy Exascale Earth System Model version 1 (E3SMv1), and the Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2) against satellite retrievals from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), Moderate Resolution Imaging Spectroradiometer (MODIS), and Multi-angle Imaging SpectroRadiometer (MISR). We find that CESM1, CESM2, and E3SMv1 underestimate dust transport to remote regions. E3SMv1 performs better than CESM1 and CESM2 in simulating dust transport and the northern hemispheric DOD due to its higher mass fraction of fine dust. CESM2 performs the worst in the Northern Hemisphere due to its lower dust emission than in the other two models but has a better dust simulation over the Southern Ocean due to the overestimation of dust emission in the Southern Hemisphere. DOD from MERRA-2 agrees well with CALIOP DOD in remote regions due to its higher mass fraction of fine dust and the assimilation of aerosol optical depth. The large disagreements in the dust extinction profiles and DOD among CALIOP, MODIS, and MISR retrievals make the model evaluation of dust spatial distributions challenging. Our study indicates the importance of representing dust emission, dry/wet deposition, and size distribution in GCMs in correctly simulating dust spatiotemporal distributions.

  DOI

Recent grants

• Collaborative Research: Cirrus Cloud Formation and Microphysical Properties from In-situ Observed Characteristics to Global Climate Impacts

  NSF · $361k · 2019–2022

• Collaborative Research: Cirrus Cloud Formation and Microphysical Properties from In-situ Observed Characteristics to Global Climate Impacts

  NSF · $458k · 2017–2020

Frequent coauthors

• Chenglai Wu

  135 shared

• Kai Zhang

  Pacific Northwest National Laboratory

  126 shared

• S. J. Ghan

  Pacific Northwest National Laboratory

  90 shared

• R. C. Easter

  Pacific Northwest National Laboratory

  76 shared

• Zheng Lu

  Texas A&M University

  74 shared

• Yves Balkanski

  Centre National de la Recherche Scientifique

  69 shared

• Susanne E. Bauer

  Goddard Institute for Space Studies

  69 shared

• Po‐Lun Ma

  Pacific Northwest National Laboratory

  64 shared

Awards & honors

• University-Level Distinguished Achievement Award for Researc…
• Research Impact Award, 2025
• Fellow, American Geophysical Union (AGU), 2023
• Fellow, American Meteorological Society (AMS), 2024
• Fellow, American Association for the Advancement of Science…

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