The research programme of trace tackles four scientific challenges 

Challenge 1 stems from the broad range of spatial scales across which ghg emissions are distributed. Scales go from local, at intense point sources like industrial sites, through more diffuse areas like urban sources, up to national and global scales. This is a major challenge for developing robust ghg quantification methods  to deliver the best results.

• This challenge will be tackled by combining satellite measurements with 3d atmospheric transport models to accurately measure the global distribution of ghg emissions at a resolution down to few kilometers, and high-resolution atmospheric plume dispersion models with arrays of low-cost sensors to monitor local industrial sites emissions at finer scale.

Challenge 2 is to ensure that all sources of error in sensor measurements, both satellites and in-situ low cost sensors, and models will be rigorously characterized, and that the methods developed to measure ghg emissions will be traceable to international standards, to contribute bankable data for measuring the effectiveness of emission reduction actions.

• for low-cost sensors, performance will be verified by working with the lsce ghg metrology laboratory, to ensure the highest quality of data collection in line with standards and qa/qc tools traceable to the world meteorological organization and the bureau international des poids et mesures. For atmospheric transport models and data assimilation algorithms, performance verification will be achieved by careful calibration and cross-validation against observations, i.E. International model inter-comparisons and benchmarking programs.

Challenge 3 is to derive kilometer-scale ghg emission maps from satellites. This requires pushing the limit of instrument parameters, developing advanced radiative transfer models (transforming satellite-measured radiances into concentrations of ghg) and atmospheric inversion models (transforming concentrations into ghg fluxes based upon data assimilation techniques).

• this challenge will be addressed by integrating the knowledge from engineers and researchers from thales alenia space with lmd’s leading experts in radiative transfer modelling and lsce’s flux inversion experts, and by training young scientists across the two laboratories.

Challenge 4 is to achieve good performance of available low-cost sensors for co₂ and ch₄ for measuring industrial sites and urban sources, a potential weakness of low-cost sensors being the risk of insufficient accuracy, including drifts and biases.

• low-cost sensors will be exposed to stringent performance tests, and evaluated against ultra-precise research-class instruments at the ghg metrology laboratory of lsce. Several low-cost sensor manufacturers allready collaborate with trace researchers and committed to  improving their products.