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| Titel |
Car MAX-DOAS measurements around entire cities: quantification of NOx emissions from the cities of Mannheim and Ludwigshafen (Germany) |
| VerfasserIn |
O. Ibrahim, R. Shaiganfar, R. Sinreich, T. Stein, U. Platt, T. Wagner |
| 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 ; 3, no. 3 ; Nr. 3, no. 3 (2010-06-22), S.709-721 |
| Datensatznummer |
250001116
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| Publikation (Nr.) |
 copernicus.org/amt-3-709-2010.pdf |
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| Zusammenfassung |
| We present car Multi-Axis (MAX-) DOAS observations of tropospheric NO2
carried out on circles around the cities of Mannheim and Ludwigshafen
(Germany) on 24 August 2006. Together with information on wind speed and
direction, the total emissions of the encircled source(s) are quantified
from these measurements. In contrast to recent similar studies based on
zenith scattered sun light (elevation angle of 90°), we use a MAX-DOAS
instrument mounted on a car, which observes scattered sun light under
different elevation angles (here 45°, and 90°). Compared to simple
zenith sky observations, MAX-DOAS observations have higher sensitivity and
reduced uncertainty, and avoid systematic offsets in the determination of
the vertically integrated trace gas concentration. The determination of the
absolute value of the integrated tropospheric trace gas concentrations is
especially important for the calculation of absolute trace gas fluxes
through arbitrary transects. However, even if emission sources are
completely surrounded, systematic offsets in the measured vertically
integrated trace gas concentration can lead to errors in the determined
total emissions, especially for observations around extended areas. In this
study we discuss and quantify different error sources. In most cases, the
largest error source is the variability and imperfect knowledge of the wind
field. In addition – depending on the trace species observed - also
chemical transformations between the emission sources and the measurement
location have to be considered. For that purpose we use local observations
within the encircled area to quantify and/or correct these errors. From our
observations we derive a total NOx emission from the
Mannheim/Ludwigshafen area of (7.4±1.8)×1024 molec/sec,
which if assumed to be constant throughout the year would correspond to a
total emission of 17 830±4340 t/yr (calculated with the mass of
NO2 t/yr, consistent with existing emission estimates. From our
observations it is also possible to separately determine the average influx
into the Mannheim/Ludwigshafen area (5.4±0.9×1024
molec/sec or 13 010±2170 t/yr) and the average outflux (12.8±1.8×1024 molec/sec
or 13 010±4340 t/yr). |
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