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Titel |
NO2 measurements in Hong Kong using LED based long path differential optical absorption spectroscopy |
VerfasserIn |
K. L. Chan, D. Pöhler, G. Kuhlmann, A. Hartl, U. Platt, M. O. Wenig |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1867-1381
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Digitales Dokument |
URL |
Erschienen |
In: Atmospheric Measurement Techniques ; 5, no. 5 ; Nr. 5, no. 5 (2012-05-03), S.901-912 |
Datensatznummer |
250002856
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Publikation (Nr.) |
copernicus.org/amt-5-901-2012.pdf |
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Zusammenfassung |
In this study we present the first long term measurements of atmospheric
nitrogen dioxide (NO2) using a LED based Long Path Differential Optical
Absorption Spectroscopy (LP-DOAS) instrument. This instrument is measuring
continuously in Hong Kong since December 2009, first in a setup with a 550 m
absorption path and then with a 3820 m path at about 30 m to 50 m above
street level. The instrument is using a high power blue light LED with peak
intensity at 450 nm coupled into the telescope using a Y-fibre bundle. The
LP-DOAS instrument measures NO2 levels in the Kowloon Tong and Mongkok
district of Hong Kong and we compare the measurement results to mixing ratios
reported by monitoring stations operated by the Hong Kong Environmental
Protection Department in that area. Hourly averages of coinciding
measurements are in reasonable agreement (R = 0.74). Furthermore, we used
the long-term data set to validate the Ozone Monitoring Instrument (OMI)
NO2 data product. Monthly averaged LP-DOAS and OMI measurements
correlate well (R = 0.84) when comparing the data for the OMI overpass
time. We analyzed weekly patterns in both data sets and found that the
LP-DOAS detects a clear weekly cycle with a reduction on weekends during rush
hour peaks, whereas OMI is not able to observe this weekly cycle due to its
fix overpass time (13:30–14:30 LT – local time). |
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