Observations of NO2 at the Manila Observatory in the Ateneo de Manila Campus (Quezon City, Philippines) are analyzed. These have been made with a Differential Optical Absorption Spectroscope (DOAS) during the two months of June and August 2002. The analysis shows that the average concentration in August is greater than that of June. The average pattern of the variation during a 24-hour period is semi-diurnal. Maximum concentrations occur in the morning as well as in the evening. The evening maximum is higher than the morning maximum. The day-to-day variations indicate the occurrence of four distinct types of diurnal variations. An attempt is made to simulate the occurrence of one of the types with an atmospheric model. The simulation indicates that the diurnal variation of the concentration is due to the wind variations accompanying a sea breeze.
[Presented at the Samahang Pisika ng Pilipinas (SPP) Congress, 2003.]