Lidar Measurement of Ammonia Concentrations and Fluxes in a Plume from a Point Source

Abstract

A field experiment was performed that demonstrated the ability of a scanning carbon dioxide (CO2) coherent lidar system to measure the concentration distribution of ammonia in a plume from a point source. This application of the differential absorption lidar (DIAL) method used wavelengths of CO2 lasers at 10.288 μm (online) and 10.274 μm (offline). The addition of wind information, which was obtained from Doppler measurements with the same lidar, permitted ammonia flux measurements through a vertical plane. The measurements were performed in the early morning when the atmosphere was stable, cool, and dry. Ammonia fluxes calculated from the lidar data showed satisfactory agreement with the ammonia release rates measured by a flowmeter. Modifications are planned to improve sensitivity and to enable measurement of ambient ammonia concentrations in polluted regions.