Reliable greenhouse gas (GHG) observations (e.g. CO2, CH4, N2O) and complementary chemical and isotopic tracer measurements (e.g. δ13C(CO2), δ18O(CO2), δ13C(CH4), δ2H(CH4), well as radioactive tracers e.g. radon, 14CH4, 14CO2) are critical for tracking emissions, detecting changes in atmospheric composition, understanding sources and sinks, and informing effective climate policy. As GHG mitigation strategies and reduction targets increasingly rely on precise, long-term data, it is essential to ensure that measurements are accurate and comparable across time and space. Metrology, the science of measurement, plays a vital role in this process by providing standardised calibration methods, uncertainty assessment, and traceability to international reference standards and scales. While metrology has traditionally been applied in controlled laboratory settings, its principles are increasingly critical to real world, in situ atmospheric observations, where long-term consistency, cross-network comparability, and data integrity are key. Additionally, emerging measurement platforms including UAVs, mobile laboratories, and low-cost sensor networks present new calibration challenges that require innovative metrological approaches. Strengthening the connection between metrology and in situ atmospheric observations is key to building globally consistent datasets that support climate research, emissions verification, and international reporting.
This session aims to foster cross-disciplinary dialogue and highlight advances that improve the comparability of GHG and tracer measurements across spatial and temporal scales. We invite contributions that explore novel or improved calibration strategies, uncertainty quantification, interlaboratory comparisons, and traceability chains for GHGs, chemical, stable isotope, and radioactive tracers. Of particular interest are studies that address harmonisation between measurement networks, improvements in temporal and spatial resolution, and integration with satellite data or modelling frameworks.