- 著者
- Masayuki Takigawa Prabir K. Patra Yutaka Matsumi Surendra K. Dhaka Tomoki Nakayama Kazuyo Yamaji Mizuo Kajino Sachiko Hayashida
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- vol.16, pp.86-91, 2020 (Released:2020-05-27)
- 参考文献数
- 39
- 被引用文献数
- 3 17
The severe air pollution events continue to occur every year during late October and early November in Delhi, forcing air/land traffic disruptions and anxiety in the daily life of the citizens. We analyze the behaviors of the air pollution events in October and November 2019 that arose from the crop-residue burning as seen using remote sensing techniques. Transport pathways and the mean transit time from the fire hotspots are evaluated using the FLEXPART (FLEXible PARTicle dispersion model). Our results suggest that the polluted regions in Delhi are partly influenced by the crop-residue burning. The uncertainty of our evaluation can be attributable to insufficient information on emission sources because the biomass burning emission based on daily-basis fire radiative power (FRP) of Moderate-Resolution Imaging Spectroradiometry (MODIS) is significantly degraded by the existence of hazy clouds. In future, it is desirable to establish a dense measurement network between Punjab and Delhi for the early detection of the source signals of aerosol emissions and their transport in this region. The FLEXPART model simulation shows the transport of emission signals from Punjab to Delhi, which further expands toward the Bengal region within a span of two days.
- 著者
- Masayuki Takigawa Prabir K. Patra Yutaka Matsumi Surendra K. Dhaka Tomoki Nakayama Kazuyo Yamaji Mizuo Kajino Sachiko Hayashida
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- pp.2020-015, (Released:2020-04-06)
- 被引用文献数
- 17
The severe air pollution events continue to occur every year during late October and early November in Delhi, forcing air/land traffic disruptions and anxiety in the daily life of the citizens. We analyze the behaviors of the air pollution events in October and November 2019 that arose from the crop-residue burning as seen using remote sensing techniques. Transport pathways and the mean transit time from the fire hotspots are evaluated using the FLEXPART (FLEXible PARTicle dispersion model). Our results suggest that the polluted regions in Delhi are partly influenced by the crop-residue burning. The uncertainty of our evaluation can be attributable to insufficient information on emission sources because the biomass burning emission based on daily-basis fire radiative power (FRP) of Moderate-Resolution Imaging Spectroradiometry (MODIS) is significantly degraded by the existence of hazy clouds. In future, it is desirable to establish a dense measurement network between Punjab and Delhi for the early detection of the source signals of aerosol emissions and their transport in this region. The FLEXPART model simulation shows the transport of emission signals from Punjab to Delhi, which further expands toward the Bengal region within a span of two days.
- 著者
- Tomoki NAKAYAMA Hiroyuki SUZUKI Satomi KAGAMITANI Yuka IKEDA Akihiro UCHIYAMA Yutaka MATSUMI
- 出版者
- (公社)日本気象学会
- 雑誌
- 気象集誌. 第2輯 (ISSN:00261165)
- 巻号頁・発行日
- vol.93, no.2, pp.285-308, 2015 (Released:2015-05-14)
- 参考文献数
- 60
- 被引用文献数
- 8 65
Laboratory experiments were conducted for characterizing the performance of two commercially available instruments employed for the measurement of light absorption and scattering coefficients of aerosols at λ = 405, 532, and 781 nm (using three-wavelength photoacoustic soot spectrometer; PASS-3) as well as at 375 nm (using photoacoustic extinctiometer; PAX) based on photoacoustic spectroscopy and reciprocal nephelometry, respectively. The calibration factors (conversion factors from the readout to real values) associated with scattering measurements, estimated using gaseous molecules, mono-disperse polystyrene latex and ammonium sulfate particles, and/or poly-disperse ammonium sulfate particles, are in good agreement with one another, typically within 5 %, 5 %, and 10 % at 375, 405, and 781 nm, respectively. In contrast, a significant particle size dependency was observed for the calibration factors at 532 nm, which is possibly because of a combination of differences in the polarization states of the lasers relative to the scattering planes and large truncation angle. Considering the estimated effective truncation angle, the typical uncertainties in calibration factors for scattering when measuring non- or weakly light-absorbing particles, with volume-based geometrical diameters of less than 700 nm, were estimated to be 12 %, 7 %, 34 %, and 17 %, at 375, 405, 532, and 781 nm, respectively. The typical uncertainties in the calibration factors for absorption measurements, which were determined using poly-disperse propane soot particles, were estimated to be 6 %, 4 %, 8 %, and 11 %, at 375, 405, 532, and 781 nm, respectively. The calibration factors for absorption determined by the poly-disperse soot particles at 375 and 405 nm were 48 % and 36 % smaller than those by light absorption of NO2 molecules possibly because of NO2 photolysis, although good agreement was observed at 532 nm. These results suggest that the photolysis effect should be taken into account when light absorption by NO2 is used for calibration at 375 and 405 nm.