Thermo Scientific Model 49i Ozone Analyzer is a dual-cell, UV Photometric analyzer for the measurement of ozone concentrations in ambient air ranging from 0.05ppb to 200ppm. As O3 molecules absorb UV light at a wavelength of 254 nm, the degree to which the UV light is absorbed is directly related to the ozone concentration as described from Beer-Lambert Law (www.thermoscientific.com). The response time of this instrument is of 20 seconds but at Chacaltaya data are stored with a one-minute resolution.
Automatic zero and span checks are performed daily until 2017, but due to an internal failure, zero checks started being performed manually every 2 weeks since 2018.
The instrument was calibrated against a traceable standard in 2017 at the WMO regional training center (Argentina).
Contact person in CHC: Isabel Moreno