OZONE MEASUREMENTS BY ZENITH-SKY SPECTROMETERS - AN EVALUATION OF ERRORS IN AIR-MASS FACTORS CALCULATED BY RADIATIVE TRANSFER MODELS

摘要

Calculations of air-mass factors (AMFs) for ground-based zenith-sky UV-visible spectrometers are presented and discussed. Causes and size of errors in AMFs of ozone in the visible are evaluated. Errors can be caused by approximations in the calculation (intensity-weight approximation, ignoring the finite field of view of the instrument); by approximation in the scheme of the calculation (single scattering, ignoring refraction); or by variable geophysical parameters (vertical profile of constituents). These relative errors in AMF cause identical relative errors in vertical columns of ozone deduced from measurements by zenith-sky spectrometers. The mean of the relative errors of ozone AMFs due to using one set of AMFs for all seasons and locations is +/- 2.4% when averaged over the commonly used range of solar zenith angles. [References: 23]