A Picarro G2301 trace gas analyser, serial number: CFADS2167, used at Tacolneston atmospheric monitoring station. After 2025-07-22 a G2401 with serial number CFKADS2532 was used instead. Both analysers have been combined into a single "virtual" instrument here. Both analysers uses cavity ringdown spectrocopy (CRDS) to make in situ measurements of CO2 and CH4 in the near-infrared region - see Crosson et al. (2008) for details of this technique: https://doi.org/10.1007/s00340-008-3135-y