Technical note: a new method for the Lagrangian tracking of pollution plumes from source to receptor using gridded model output

摘要

Lagrangian particle dispersion models (LPDMs) are powerful and popular toolsused for the analysis of atmospheric trace gas measurements. However, it canbe difficult to determine the transport pathway of emissions from theirsource to a receptor using the standard gridded model output, particularlyduring complex meteorological scenarios. In this paper we present a method toclearly and easily identify the pathway taken by only those emissions thatarrive at a receptor at a particular time, by combining the standard griddedoutput from forward (e.g., concentration) and backward (e.g., residencetime) LPDM simulations. By comparing the pathway determined from this methodwith particle trajectories from both the forward and backward models, weshow that this method successfully restores much of the Lagrangianinformation that is lost when the data are gridded. A sample analysis ispresented, demonstrating that the source-to-receptor pathwaydetermined from this method is more accurate and easier to use thanexisting methods using standard LPDM products (gridded fields of,e.g., concentrations and residence time). As demonstrated in anevaluation and an example application, the method requires agreementbetween the transport described by the forward and backward simulationsand thus provides a means to assess the quality and reversibility ofthe simulation. Finally, we discuss the potential for combining thebackward LPDM simulation with gridded data from other sources (e.g.,chemical transport models) to obtain a Lagrangian sampling of the airthat will eventually arrive at a receptor. Based on the advantagespresented here, this new method can complement or even replace many ofthe standard uses of backward LPDM simulations.