Improved determination of atmospheric trace gas emissions through observation-based analysis techniques: The AMIGO global initiative

Atmospheric composition is rapidly changing owing to emissions of air pollutants from natural sources and human activities, which directly affect air quality and climate. Accurate quantification of these emissions is crucial for air quality forecasting, developing environmental mitigation policies, understanding the Earth’s climate, and projecting its evolution. In addition to emission inventories based on emission factors and activity data, observation-based approaches that rely on satellite, aircraft, and ground-based measurements have emerged as powerful tools for constraining emissions. Over the past two decades, advances in global observing systems, chemistry-transport models, inversion approaches, and statistical and machine learning methodologies have greatly improved the robustness of observation-based emission estimates for major air pollutants, greenhouse gases, and aerosols. To address the growing need for accurate emission information for reactive gases and aerosols, the Analysis of eMIssions usinG Observations (AMIGO) initiative was launched within the International Global Atmospheric Chemistry (IGAC) project. AMIGO fosters international collaboration and synthesis efforts, supports the development of new scientific approaches, and trains future leaders in the field. This article reviews recent progress and challenges in observation-based air pollutant emission estimation and outlines the role of AMIGO in advancing policy-relevant emission information to support societal needs.