TITLE:
Simultaneous Monitoring of Nitrogen Dioxide and Aerosol Concentrations with Dual Path Differential Optical Absorption Spectroscopy
AUTHORS:
Hayato Saito, Yutaro Goto, Yusaku Mabuchi, Ilham Alimuddin, Gerry Bagtasa, Naohiro Manago, Hitoshi Irie, Ippei Harada, Toshihiko Ishibashi, Kazunori Yashiro, Shumpei Kameyama, Hiroaki Kuze
KEYWORDS:
Differential Optical Absorption Spectroscopy (DOAS); Wind Lidar; Urban Air Pollution; Nitrogen Dioxide; Aerosol; PM2.5; SPM
JOURNAL NAME:
Open Journal of Air Pollution,
Vol.3 No.1,
March
27,
2014
ABSTRACT: Differential optical absorption spectroscopy (DOAS) is a useful technique
for measuring nitrogen dioxide (NO2) and aerosol, the most important
species in urban environmental pollution. This paper reports on the results of
our dual path DOAS measurements recently conducted in Chiba City, Japan, using
xenon flashlights equipped on tall constructions as aviation obstruction
lights. Because of the proximity of the southern DOAS path to an industrial
area, it is found that the level of air pollution generally increases with the
dominance of westerly winds, from the plausible source area to the observation
light path. This situation is consistent with the result of wind lidar measurement
covering a sector of ±28? with the observation range of approximately 2.8 km.
In spite of the fact that the two DOAS paths, having path lengths of 5.5 and
3.5 km each, are located in separated regions of Chiba City, the observed
temporal behavior was similar for both nitrogen dioxide and aerosol, though the
southern path tends to exhibit slightly higher pollution levels than the
northern counterpart. Additionally it is confirmed that size information of
aerosol particles can be derived from the DOAS data through the analysis of the
wavelength dependence of the aerosol optical thickness, which shows fairly good
correlation with the mass ratio between PM2.5 and suspended particulate matter
(SPM) obtained from the in-situ sampling station measurement. Thus, the DOAS approach can also be utilized for
obtaining information on PM2.5 that is considered to be more harmful to human
health than SPM.