Lidar Calibration Technique for Quantifying Spray Drift

Aerial spraying with pesticides is a common approach to weed, insect pest, and disease control in a range of settings, including pest eradication in populated environments. With such a wide range of application scenarios, there is need to quantify the likely level of spray drift in order to assess risks to the environment and/or public health. Additionally, more accurate quantification will allow for improved predictions and better policy relevant decisions to be made for mitigation efforts (e.g., instigate buffer zones around sensitive areas or to change the application method). Therefore it is desirable to optimize aerial applications to reduce risks while maintaining efficacy. Reliable quantification and the subsequent prediction of the amount and downwind extent of drift out of the target zone is essential to optimization efforts. Current models do not completely account for the turbulence conditions above aerodynamically rough surfaces, where sprays are often applied. We report on a field study designed to test the implications of canopy roughness on spray drift. A combined LiDAR and ground sampling study with a measurement profile of twice the canopy height was conducted in March 2015 over a 3.8 meter pine canopy. This paper will present a calibration technique to combine LiDAR “stares” and scans to quantify drift downwind.