Measuring Nitrogen Dioxide Vertical Column Density Distribution over Hong Kong Using Solar Differential Absorption Spectroscopy

Nitrogen oxides are important trace gases in the atmosphere that have an impact on human health, atmospheric chemistry and climate. A network of 14 in-situ monitoring stations placed throughout Hong Kong provides good data for our understanding of the NO2 pollutant at street level. In order to derive a comprehensive four-dimensional (spatial and temporal) picture of this pollutant, this project will install an inexpensive network of solar spectrometers as a complement to the existing network to measure the total vertical column density (VCD) of NO2 over the territory. A similar instrument installed in a van as a mobile platform will measure the VCD along major highways during pollution episodes at different seasons in the study period. Studies of the changes of NO2 VCD at various levels in the boundary layer using a low flying aircraft will also help to fine tune a pollutant transport model for better predictions.