A fast and precise chemiluminescence ozone detector for eddy flux and airborne application
A. Zahn, J. Weppner, H. Widmann, K. Schlote-Holubek, B. Burger, T. Kühner, H. Franke
- Datum: Atmos. Meas. Tech., 5, 363–375, 2012
A commercially available dry chemiluminescencen (CI) instrument for fast and precise measurement of ozone (O3) is specified. The sensitivity is ~9000 counts s−1 perppbv of ozone. Its precision is entirely determined by thenumber of photons reaching the detector (being a photomultiplier), i.e. is quantum-noise limited. The relative precision (ΔO3/O3 in %) thus follows Poisson statistics and scales withthe square root of the measurement frequency f and with theinverse O3 mixing ratio: ΔO3/O3 α f 0.5·O3−0.5 . At typical O3 mixing ratios between 10 and 100 ppbv (and 1 bar), the precision is 0.3–1.0% at f = 10 Hz. The maximum measurement frequency is 50 Hz. The mechanical and electronic setup as well as the instrument performance is described. Recommendations on the adequate inlet tube configuration (inlettube length, sampling flow) and on the way of calibration atstationary ground-based platforms and onboard aircraft are given.