In 2006, WUR acquired and fully equipped a light aircraft for airborne measurements of turbulent fluxes. Named after its purpose, the PH-WUR carries out regular flights across the Netherlands, for example over peatlands, to measure greenhouse gas emissions.
The aerial platform, which was developed for the EU-FP5 RECAB-project, is based on the certified aircraft Sky Arrow ERA (Environmental Research Aircraft), equipped with sensors to measure threedimensional wind and turbulence together with gas concentrations and other atmospheric parameters at high frequency.
The aircraft engine is mounted in a pusher configuration and has a cruise flight-speed of 85 knots with an endurance of 3.5h, allowing it to cover flight distances of up to 400km. Operating altitudes can range from 10m above ground level to more than 3500m above sea level.
Do you want to know when and where the PH-WUR is flying? We mostly fly on Tuesdays and Wednesdays, on average every 1-2 weeks, depending on weather and flight conditions. Of course, we have the required (low-flying) permits and our professional pilots are specially trained for this.
Atmospheric turbulence measurements are made with the "Best-Aircraft-Turbulence Probe" (BAT-probe), developed by NOAA's Atmospheric Turbulence and Diffusion Division (NOAA-ATDD) and Airborne Research Australia (ARA). In brief, the BAT-probe measures the velocity of air with respect to the aircraft using a hemispheric 9-hole pressure sphere that records static and dynamic pressures by means of four differential pressure transducers [Crawford and Dobosy, 1992].
The actual wind components (horizontal U, V and vertical W) relative to the ground are calculated introducing corrections for three-dimensional velocity, pitch, roll and heading of the aircraft. Those corrections are made using a combination of GPS velocity measurements and data from two sets of three orthogonal accelerometers mounted at the center of gravity of the aircraft and in the centre of the hemisphere. Atmospheric densities of carbon dioxide and water vapour are recorded at 50Hz by a Li-Cor 7500 (Li-Cor, USA) open path infrared gas analyzer installed on the aircraft nose.
See Bsik ME2 project website for more details or download the poster displayed below.
These measurements are essential in regionalization, scaling and attribution research of GHG fluxes and emissions. The aircraft has been successfully deployed for several campaigns in the Netherlands and Southern France.