Evaluation of source–receptor relationship for atmospheric pollutants using approaches of trajectory modelling, cluster, probability fields analyses and adjoint equations

In this paper, different approaches and models to evaluate source–receptor relationship for potential atmospheric pollutants on examples of source and receptor points/regions (the Euro–Arctic and North Pacific) are considered. The forward–backward trajectory modelling approach combined with statistical methods of cluster analysis and probability fields, and adjoint equations approach are discussed and illustrated. The combined consideration of the atmospheric transport pathways, airflow probability fields, and sensitivity functions of the source–receptor relationship as well as estimation of its spatial distribution and levels of joint impact/influence is presented. Based on the principal and adjoint equations for the regional transport of pollutants in the atmosphere a method for receptor sensitivity function assessments is considered and illustrated for an example study of Nordic countries regional sensitivity to radioactive contamination from hypothetical accidental releases.