Session 1:
Air Quality Impacts

Co-chairs: Nestor Rojas and Vinayak Sinha

Ambient Field Studies in Non-Urban Areas
Areas and regions of the world that have not been urbanized provide important insights into natural processes and baseline “unpolluted” conditions of the atmosphere. These could be high-altitude remote sites, the Amazon rainforest, the remote marine atmosphere, the upper troposphere, and uninhabited icy cold regions, to name a few. In this sub-session, we welcome submissions that address air quality impacts on health, vegetation, agriculture and natural ecosystems.

Ambient Studies in Urban Areas and Indoor Air Quality
Urban and industrial areas generate most of the anthropogenic pollutant emissions to the atmosphere. They also concentrate on the highest exposure to air pollutants and the health risks associated with ambient and indoor air. In this sub-session, we welcome submissions of novel air pollution studies covering pollutant emission sources, pollutant chemical and physical characteristics, and the consequential effects on human health and the environment in areas influenced by urban and industrial activities and indoor environments. We also welcome studies on the effectiveness of mitigation strategies, policy frameworks, and technological innovations designed to address these challenges.

Session 2:
Atmospheric Chemistry: Climate and Weather Impacts on Air Quality

Co-Chairs: Abdus Salam and Owen Cooper

Poor air quality is primarily the result of air pollutant emissions and chemistry, but day-to-day changes in weather patterns, short-term climate variability (e.g. ENSO), and long-term climate change directly impact the intensity and longevity of air pollution episodes.  This session will focus on new scientific research that identifies and quantifies the impacts of weather and climate on surface air quality.  As surface air quality is also affected by long-range transport and background concentrations of air pollutants, this session will also explore the impacts of weather and climate on air pollution levels in the free troposphere or at remote surface locations. 

Session 3:
Chemistry Processes and Mechanism Fundamentals

Co-Chairs: Clare Murphy and Hugh Coe 

Understanding atmospheric physicochemical processes is pivotal for quantitatively describing its past, current and future composition. This is why this session invites curiosity-oriented and fundamental contributions that will provide a better understanding of key atmospheric processes from aerosol optics, gas-phase, multiphase and heterogeneous kinetics, new aerosol formation and transformations, and emerging contaminants and environmental problems.  Contributions highlighting novel analytical theoretical and numerical approaches, process model studies and new chemical mechanism development are welcome.

Session 4:
Atmospheric Chemistry in the Changing Earth System 

Co-Chairs: Yugo Kanaya, Evelyne Touré and Maheswar Rupakheti

Atmospheric chemical composition is highly impacted by environmental processes involving changes in the Earth’s surface system (land, oceans, cryosphere, and ecosystems) and human activities. In turn, atmospheric chemistry also affects the Earth system. This session covers recent findings from observational and modelling studies on these interactions and feedback. Air pollutants, oxidants, aerosols, precursor gases, and greenhouse gases are all of our interests here. We welcome presentations on 1) emissions from intensified wildfires and their impact, 2) interactions with changing sea/ice/snow/land cover state (deposition, emission, heterogeneous chemistry etc.), including biological gas/aerosol emissions, 3) biogeochemical cycles and feedbacks relevant to climate and environmental change, and 4) coupled human-natural system change relevant to atmospheric chemistry. Interdisciplinary studies relevant to SOLAS (Surface Ocean – Lower Atmosphere Study) and iLEAPS (Integrated Land Ecosystem–Atmosphere Processes Study) projects are also welcomed.

Session 5:
Recent Campaigns and New Developments in Observations and Modelling

Co-Chairs: David Tarasick and Nicolas Huneeus

This session aims to facilitate the integration of new observations and new analyses in atmospheric chemistry research, which will promote scientific understanding, inspire further investigation and collaboration, identify critical issues and support prediction and decision-making for global sustainability.  We invite submissions presenting new observations, especially those that challenge current understanding and stimulate further investigation. We welcome contributions discussing the numerical analysis of data from observations and models, model evaluation against observations, data assimilation and application for prediction, and machine learning.  All types of observation are in scope, from the surface to the upper atmosphere, across multiple spatial and time scales. We also welcome studies of new methodological developments in measurement and theory, including physical, chemical, and statistical models.

Session 6:
Panel Discussion of Future Directions and Current Challenges in Atmospheric Chemistry

Co-Chairs: Liya Yu and Rebecca Garland

Panel discussions will allow one to discuss current and future cross-cutting issues in atmospheric chemistry. Panelists will be invited from all five sessions (listed above), as well as IGAC working groups and activities.