Diurnal Variations of NO2 Concentrations at the Manila Observatory, Quezon City

A combined observational and theoretical study of diurnal variations of NO2 concentrations of the air at the Manila Observatory (Quezon City, Philippines) in June and August 2002 was made. The concentrations were monitored using a Differential Optical Absorption Spectroscope (DOAS). The analysis showed that the average NO2 concentration in August is greater than that of June. The average time variation was semi-diurnal with a major maximum in the evening and a slight maximum in the morning. The daily variations may be classified into four types of diurnal variations according to the occurrence of maxima in the concentrations. A simple fluid dynamical model was formulated in order to explain the occurrence of these types. Integrations of the model indicate that the types can be explained primarily in terms of the horizontal transport of pollutants due to local winds.

[Loyola Schools Review, 2005]