Mobile Greenhouse Gas Emission Surveys from Canadian Landfills (2022)

The inlet was mounted on a mast on the roof of the vehicle at a height of 80 cm, resulting in a total elevation of approximately 2.5-2.7 m above ground level. The mast supported other essential instruments, including a Gill Ultrasonic Anemometer for measuring wind speed and direction data with precision of 3% route mean square error (RMSE) for wind speed and ±3° for wind direction, a digital compass for precise orientation, and a high-accuracy GPS unit to track the vehicle's location throughout our surveys.

Every day, we performed GPS calibration by driving the vehicle in all four cardinal directions—north, south, east, and west. This allowed us to assess the accuracy of the GPS readings and make necessary adjustments to ensure reliable positioning data. All of our sensor data were logged using a CR1000X Campbell Scientific data logger, allowing us to synchronize the data collection from each instrument.

To ensure the accuracy of our gas measurements, we utilized benchmarking gases to evaluate the analyzer’s performance before and after the campaign in the lab using traceable gases, and daily during the campaign using compressed air cylinders of known concentration. Additionally, we conducted breath tests at the gas inlet prior to each survey to assess and correct for the time lag between the inlet and the analyzer introduced by the pump, tubing, and analyzer delay.

We sampled by driving slowly (~15-20 km hr-1) from the ambient toward the elevated CH4 concentration and then back to the ambient to sample the entire crosswind section of the plume. In most cases, public road access was the limiting factor for the number and location of the offsite transects.