Differential Optical Absorption Spectroscopy Measurements of Nitrogen Dioxide in Hong Kong

The aim of this project is to reassemble an NO2 differential optical absorption spectroscopy (DOAS) system (which had been in use at CityU in the past) and to develop a retrieval algorithm that can optimally handle the specific characteristics of this instrument. To evaluate the uncertainties of the measurements, the resulting NO2 time series will be compared with satellite measurement data, e.g. NO2 concentrations measured by NASA’s Ozone Monitoring Instrument (OMI) and by ESA's Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY). The instrument will be operated in two different modes. The first mode, in which the instrument looks directly into the sun, provides optimal conditions for comparison with satellite data, because the entire atmosphere is sampled. The second mode, in which an artificial light source is used to sample a path close to the ground, provides more insights in surface air pollution conditions in Hong Kong.