Polar grid-based nonparametric trajectory analysis for improved near-source air pollutant monitoring applications

Nonparametric Trajectory Analysis (NTA) combines continuous air pollutant concentrations with local-scale back trajectories estimated from wind speed and direction to quantify source area impacts at a monitoring site. Previously, NTA calculations used regular grid spacing and kernel smoothing which limited the spatial variability in NTA maps around monitoring sites located near sources. NTA was modified to be based on a polar grid to produce finer resolution close to the site. Polar NTA results were compared to the previous version using one year of continuous data from a near-road monitoring network site in St. Louis, MO.

Impact/Purpose

A polar grid-based version of Non-parametric Trajectory Analysis (NTA) was developed for application to near source air pollutant monitoring sites with continuous high time resolution concentration and wind data. Polar NTA results using data from a Near Road Monitoring Network site provided estimates of roadway impacts using only the monitoring site data as compared to other data analysis approaches that require comparison with other nearby sites. The polar grid increased the resolution of NTA estimated contributions near the monitoring site which allowed potential influences of nearby buildings and roadway configurations to be visualized. Polar NTA provides an improved data analysis approach for identifying and quantifying the relative impacts of different local sources on air pollutant concentrations at monitoring sites.

Citation

Burke-Norris, J., R. Henry, W. Wetherell, AND J. Brunnert. Polar grid-based nonparametric trajectory analysis for improved near-source air pollutant monitoring applications. Elsevier B.V., Amsterdam, NETHERLANDS, 374:121951, (2026). [DOI: 10.1016/j.atmosenv.2026.121951]

DOI: Polar grid-based nonparametric trajectory analysis for improved near-source air pollutant monitoring applications