Measurement of regional distribution of atmospheric NO2 and aerosol particles with flashlight long-path optical monitoring

We report on an air-pollution monitoring campaign in the urban Kyoto area conducted during December 2003 and January 2004. The method is based on the differential optical absorption spectroscopy (DOAS) using an aviation obstruction light (white flashlight). Three sets of DOAS spectrometers, each consisting of a telescope and a compact charge-coupled device (CCD) spectrometer, were operated to cover the southern part of the city area. Three sites were chosen in the urban Kyoto area, and the average concentrations of NO2 were measured with optical path lengths of 2.7, 4.1, and 7.1 km. The aerosol optical thickness was simultaneously measured for the path length of 2.7 km. It is found that the temporal variations of the retrieved amount of the pollution species agree with each other and they are also consistent with concurrent results of the ground sampling measurements.