Research

Our research group focuses on a wide range of topics on atmospheric chemistry, greenhouse gases, and climate change, including:

  • Source, chemistry, transport, and sink of air pollutants 大气污染物(活性氮、臭氧、细颗粒物)的排放、化学、传输、沉降过程
  • Greenhouse gases budgets from bottom-up and top-down methods 温室气体收支:结合自上而下及自下而上方法
  • Chemistry-Climate-Ecosystem interactions and model development 地球系统中的气候-大气化学-生态植被相互作用机理与模式发展

Our main analytical tools are numerical models, including global-scale chemical transport model (GEOS-Chem) and climate-chemistry-ecosystem interactive earth system models (BCC-ESM, CESM), regional air quality models (GEOS-Chem, WRF-Chem, WRF-CMAQ), atmospheric dispersion models (FLEXPART, WRF-FLEXPART), and inverse modeling. We are now combining machine learning and chemical models in several applications (e.g. prediction of air quality/short-lived oxidants).

Here are some topics that we have done/currently work on:

—————————————————————1. Source, chemistry, transport, and sink of air pollutants——————————————————

(1) Ozone trends from surface to troposphere

We are continuously tracking ozone trends from surface to troposphere, using multiple measurements (surface, aircraft, ozonesonde, and satellite) and state-of-art chemical models. Our study has revealed notable increases in troposphere ozone since 1995 driven by changes in emission patterns and rising methane. Ozone is increasing fast in China in the recent decade that has caused severe ozone pollution and high oxidation capacity. We are working with the Tropospheric Ozone Assessment Report phase II (TOAR II) to explore the attribution and impact of ozone increase in East Asia.

Reference

Wang, H. et al. submitted

Wang, H. et al. Increased night-time oxidation over China despite widespread decrease across the globe, Nature Geoscience, 2023. [link]

Wang, H. et al. Global tropospheric ozone trends, attributions, and radiative impacts in 1995–2017: an integrated analysis using aircraft (IAGOS) observations, ozonesonde, and multi-decadal chemical model simulations, Atmospheric Chemistry and Physics, 2022 [link]

Lu, X. et al. Rapid increases in warm-season surface ozone and resulting health impact over China since 2013, Environmental Science & Technology Letters, 2020 [ESI 1% Highly Cited Paper] [link]

Lu, X. et al. Severe Surface Ozone Pollution in China: A Global Perspective, Environmental Science & Technology Letters, 2018. [ESI 0.1% Hot Paper] [ESI 1% Highly Cited Paper] [link]

(2) Natural and anthropogenic sources of air pollutants and mitigation strategy

We use high-resolution chemical transport model simulations to quantify the natural and anthropogenic sources contributing to surface ozone and particulate matters (PM). In particular, we improve the estimate of agricultural emissions of reaction nitrogen from soil (NOx and HONO), and find that these emissions have accelerated ozone increase in China with reductions in anthropogenic emissions. The intensive emissions from agricultural nitrogen source represent as a unique challenge for ozone mitigation in China.

Reference

Tan, W. et al. Soil Emissions of Reactive Nitrogen Accelerate Summertime Surface Ozone Increases in the North China Plain, Environ. Sci. Technol., 2023.[link]

Lu, X. et al. The underappreciated role of agricultural soil nitrogen oxide emissions in ozone pollution regulation in North China, Nature Communications, 2021 [ESI 1% Highly Cited Paper] [link]

Lu, X. et al. Exploring 2016–2017 surface ozone pollution over China: source contributions and meteorological influences, Atmospheric Chemistry and Physics, 2019 [ESI 1% Highly Cited Paper] [link]

(3) Meteorological influences on the evolution and structure of air pollutants

Meteorological factors (temperature, boundary layer, weather patterns) also modulate the evolution and structure of air pollutants. Our recent studies focus on the ozone sensitivity to temperature, weather patterns causing high ozone pollution, and nighttime ozone enhancement events caused by increasing vertical mixing.

Reference

He, G. et al. Nighttime ozone in the lower boundary layer: insights from 3-year tower-based measurements in South China and regional air quality modeling, Atmos. Chem. Phys., 2023.[link]

Liu, N. et al. Rising frequency of ozone-favorable synoptic weather patterns contributes to 2015–2022 ozone increase in Guangzhou, Journal of Environmental Sciences, 2023.[link]

He, C. et al. The unexpected high frequency of nocturnal surface ozone enhancement events over China: Characteristics and mechanisms, Atmospheric Chemistry and Physics, 22, 15243-15261, 2022 [link]

——————————————————2.Greenhouse gases budgets from bottom-up and top-down methods——————————————————

(1) Global budgets and trends of methane

We develop the methods for combining satellite and in-situ observations in inverse modeling to quantify and attribute the sources, sinks, and trends of atmospheric methane. We are continuously updating the “top-down” estimate of methane budgets and trends, using newly-developed “bottom-up” emission inventories of agricultural rice and natural wetlands, and using isotope-available models, with collaborators around the world.

Reference

Lu, X. et al. Global methane budget and trend, 2010–2017: complementarity of inverse analyses using in situ (GLOBALVIEWplus CH4 ObsPack) and satellite (GOSAT) observations, Atmospheric Chemistry and Physics, 2021 [link]

(2) Regional greenhouse gases evolution and emission inventory

We are interested in the national and regional greenhouse gas emissions for mitigation of climate change. “Top-down” estimates of methane emission in the North America have revealed significant underestimate in its magnitude and interannual variability in “bottom-up” national emission inventory. Our study also reveal intensive methane leakage from oil/gas industry that tied to activity metrics (oil/gas production, well drilling, etc.). We are also investigating how in-situ measurement of multiple greenhouse gas and air pollutant can inform emiters and industrial level activity.

Reference

Lu, X. et al. Observation-derived 2010-2019 trends in methane emissions and intensities from US oil and gas fields tied to activity metrics, Proc. Natl. Acad. Sci. U. S. A., 2023. [link]

Lu, X.et al. Methane emissions in the United States, Canada, and Mexico: evaluation of national methane emission inventories and 2010–2017 sectoral trends by inverse analysis of in situ (GLOBALVIEWplus CH4 ObsPack) and satellite (GOSAT) atmospheric observations, Atmospheric Chemistry and Physics, 2022 [link]

(3) Improving estimate of point-source greenhouse gases emissions

We have developed new methods for quantifying CO2 emissions from point-source power plants using satellite observations.

Reference

He et al. submitted

——————————————————3. Chemistry-Climate-Ecosystem interactions and model development——————————————————

(1) Climate variability impacts on atmospheric chemistry

Our work reveals that tropospheric ozone trends in the Southern Hemisphere are linked s to the poleward expansion of Hadley circulation. We also summarize how tropospheric ozone and weather/climate with each other and highlight the current gaps. We are also looking at how other climate variability (e.g. ENSO, South Asia High) influence atmospheric chemical components on multiscale.

Reference

Lu, X. et al. Surface and tropospheric ozone trends in the Southern Hemisphere since 1990: possible linkages to poleward expansion of the Hadley Circulation, Science Bulletin, 2019 [Journal Highlight Article] [link]

Lu, X. et al. Meteorology and Climate Influences on Tropospheric Ozone: a Review of Natural Sources, Chemistry, and Transport Patterns, Current Pollution Reports, 2019 [link]

(2) Atmospheric components feedback on meteorology, carbon cycle, and energy

We are studying how atmospheric components may feedback on meteorology, carbon cycle, and energy use. Our recent work investigates how shipping-induced aerosol modulate lightning activity over the oceans.

Reference

Sun et al. submitted

(3) Climate-chemistry model development

Chemistry plays an indispensable role in evolution of the atmosphere and earth system; however, many climate models either ignore or greatly simplify atmospheric chemistry, limiting both their accuracy and their scope. We developed the BCC-GEOS-Chem model, i.e. GEOS-Chem coupled with the BCC Atmospheric General Circulation Model (BCC-AGCM), and evaluated the model with in-situ and satellite observations. We are continuously updating the BCC-GEOS-Chem model, with much improved applicability for research studies and air quality predictions.

Reference

Lu, X. et al.: Development of the global atmospheric general circulation-chemistry model BCC-GEOS-Chem v1.0: model description and evaluation, Geoscientific Model Development, 2020 [link]