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| Titel |
A wide field-of-view imaging DOAS instrument for two-dimensional trace gas mapping from aircraft |
| VerfasserIn |
A. Schönhardt, P. Altube, K. Gerilowski, S. Krautwurst, J. Hartmann, A. C. Meier, A. Richter, J. P. Burrows |
| 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 ; 8, no. 12 ; Nr. 8, no. 12 (2015-12-09), S.5113-5131 |
| Datensatznummer |
250116717
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| Publikation (Nr.) |
 copernicus.org/amt-8-5113-2015.pdf |
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| Zusammenfassung |
| The Airborne imaging differential optical
absorption spectroscopy (DOAS) instrument for Measurements of Atmospheric
Pollution (AirMAP) has been developed for the purpose of trace gas
measurements and pollution mapping. The instrument has been characterized and
successfully operated from aircraft. Nitrogen dioxide (NO2) columns
were retrieved from the AirMAP observations. A major benefit of the push-broom imaging instrument is the spatially continuous, gap-free measurement
sequence independent of flight altitude, a valuable characteristic for
mapping purposes. This is made possible by the use of a charge coupled
device (CCD) frame-transfer detector. A broad field of view across track of around 48° is
achieved with wide-angle entrance optics. This leads to a swath width of
about the same size as the flight altitude. The use of fibre coupled light
intake optics with sorted light fibres allows flexible instrument positioning
within the aircraft and retains the very good imaging capabilities. The
measurements yield ground spatial resolutions below 100 m depending on
flight altitude. The number of viewing directions is chosen from a maximum of
35 individual viewing directions (lines of sight, LOS) represented by 35
individual fibres. The selection is adapted to each situation by averaging
according to signal-to-noise or spatial resolution requirements. Observations
at 30 m spatial resolution are obtained when flying at 1000 m altitude and
making use of all 35 viewing directions. This makes the instrument a suitable
tool for mapping trace gas point sources and small-scale variability. The
position and aircraft attitude are taken into account for accurate spatial
mapping using the Attitude and Heading Reference System of the aircraft. A
first demonstration mission using AirMAP was undertaken in June 2011. AirMAP
was operated on the AWI Polar-5 aircraft in the framework of the AIRMETH-2011
campaign. During a flight above a medium-sized coal-fired power plant in
north-west Germany, AirMAP clearly detected the emission plume downwind from
the exhaust stack, with NO2 vertical columns around
2 × 1016 molecules cm−2 in the plume centre. NOx
emissions estimated from the AirMAP observations are consistent with reports
in the European Pollutant Release and Transfer Register. Strong spatial
gradients and variability in NO2 amounts across and along flight
direction are observed, and small-scale enhancements of NO2 above a
motorway are detected. |
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