Methane concentrations are measured by eight CMS sensors placed around the perimeter of the METEC site at a height of 2.4 m, three of which also measure wind speed and direction. Note that additional higher sensors would be needed if very tall emission sources were present (e.g., flare stacks). Sensor locations are marked with pins in Figure . Project Canary used a Near-IR Tunable Diode Laser Absorption Spectroscopy (TDLAS) methane sensor and an R.M. Young 2D ultrasonic anemometer during the ADED controlled releases. The methane sensor has a stated accuracy of ±2% and precision of ≤ 0.125 ppm. The anemometer has a stated accuracy of ±2% ±0.1 m/s for wind speed and ±2 degrees for wind direction and a stated precision of 0.01 m/s for wind speed and 0.1 degrees for wind direction. Methane concentration, wind speed, and wind direction are measured every second and are averaged every minute by Project Canary, resulting in one data point per minute.