Methodology for Comparison of Open-Path Monitors with Point Monitors

The first measurements of a dispersed secondary pollutant (O3) using a CO2 laser based, open-path monitor are compared to readings from a chemiluminescence point monitor which traverses a common measurement path of 0.67 km. A statistical treatment is given which establishes the accuracy of comparison. Meteorological conditions as reflected by changes in pollutant variability are shown to influence the accuracy of comparison. The essential equivalence of data obtained by the point monitor and the path monitor is confirmed for selected measurement sequences while other measurement sequences identify non-optimized performance of the path monitor.