Isoprene abundances were measured using the iDirac (Bolas et al., Atm. Meas. Tech., 2020), a custom-built portable gas chromatograph with photo-ionisation detection (GC-PID). The instrument is designed for continuous and autonomous operation, with a Raspberry Pi/Arduino-controlled system, low power usage (12 W) and low gas consumption. Frequent calibration runs (typically every 5 hours) ensured maximum accuracy of the measurements. The limit of detection is 40 ppt (signal to noise of 3), with 10% precision.

Air temperature was monitored every 2 minutes by four EasyLog probes (EL-USB-2-LCD & EL-USB-2, Lascar Ltd).

Photosythetically Active Radiation (PAR) was monitored using 4 SQ-110 Quantum Apogee sensors (Campbell Scientific)