Application of adjoint tracer transport equations for evaluating source parameters

Abstract

The solution of the adjoint tracer transport equation with a properly defined forcing term could be effectively used to evaluate the emission field of atmospheric contaminants. This technique is applicable for a large class of toxic materials either for the verification of the existing emission inventories or, as a sole method, for the assessment of the source term. In this paper, we present one specific application of the adjoint tracer transport equation. In particular, we estimate the location of the source using the influence function obtained as a solution of the adjoint equation. The strength of the source is estimated from the Lagrange duality relation. The information obtained this way is important to enhance our ability to monitor nuclear testing. We discuss the mathematical algorithm with which to solve this problem along with some pertinent information concerning the network used for sampling of radioactivity on a global scale. The theoretical discussion is then illustrated with examples of applications of the method for the evaluation of the location of a nuclear test. Finally, we present a general evaluation of the accuracy of the method and compare it with the traditional approach of back trajectories. In conclusions, we evaluate the general applicability of the method for monitoring of nuclear testing and suggest the extension of the algorithm for other atmospheric tracers including toxics.