A fast and precise chemiluminescence ozone detector for eddy flux and airborne application

Abstract

A commercially available dry chemiluminescence (CI) instrument for fast and precise measurement of ozone (O3) is specified. The sensitivity is ∼9000 counts s-1 per ppbv of ozone. Its precision is entirely determined by the number of photons reaching the detector (being a photomultiplier), i.e. is quantum-noise limited. The relative precision (ΔO3/O 3 in %) thus follows Poisson statistics and scales with the square root of the measurement frequency f and with the inverse O3 mixing ratio: ΔO3/O3 ∝ f 0.5 · O 3-0.5. At typical O3 mixing ratios between 10 and 100 ppbv (and 1 bar), the precision is 0.3-1.0% at f Combining double low line 10 Hz. The maximum measurement frequency is 50 Hz. The mechanical and electronic set-up as well as the instrument performance is described. Recommendations on the adequate inlet tube configuration (inlet tube length, sampling flow) and on the way of calibration at stationary ground-based platforms and onboard aircraft are given. © 2012 Author(s).