High-resolution mapping of the NO<sub>2</sub> spatial distribution over Belgian urban areas based on airborne APEX remote sensing
We present retrieval results of tropospheric nitrogen dioxide (NO<sub>2</sub>) vertical column densities (VCDs), mapped at high spatial resolution over three Belgian cities, based on the DOAS analysis of Airborne Prism EXperiment (APEX) observations. APEX, developed by a Swiss-Belgian co...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2017-05-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | http://www.atmos-meas-tech.net/10/1665/2017/amt-10-1665-2017.pdf |
| _version_ | 1811197910929375232 |
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| author | F. Tack A. Merlaud M.-D. Iordache T. Danckaert H. Yu C. Fayt K. Meuleman F. Deutsch F. Fierens M. Van Roozendael |
| author_facet | F. Tack A. Merlaud M.-D. Iordache T. Danckaert H. Yu C. Fayt K. Meuleman F. Deutsch F. Fierens M. Van Roozendael |
| author_sort | F. Tack |
| collection | DOAJ |
| description | We present retrieval results of tropospheric nitrogen dioxide
(NO<sub>2</sub>) vertical column densities (VCDs), mapped at high spatial
resolution over three Belgian cities, based on the DOAS analysis of Airborne
Prism EXperiment (APEX) observations. APEX, developed by a Swiss-Belgian
consortium on behalf of ESA (European Space Agency), is a pushbroom
hyperspectral imager characterised by a high spatial resolution and high
spectral performance. APEX data have been acquired under clear-sky conditions
over the two largest and most heavily polluted Belgian cities, i.e. Antwerp
and Brussels on 15 April and 30 June 2015. Additionally, a number of
background sites have been covered for the reference spectra. The APEX
instrument was mounted in a Dornier DO-228 aeroplane, operated by Deutsches
Zentrum für Luft- und Raumfahrt (DLR). NO<sub>2</sub> VCDs were retrieved from
spatially aggregated radiance spectra allowing urban plumes to be resolved at the
resolution of 60 × 80 m<sup>2</sup>. The main sources in the Antwerp area appear to be
related to the (petro)chemical industry while traffic-related emissions dominate
in Brussels. The NO<sub>2</sub> levels observed in Antwerp range between 3 and 35 × 10<sup>15</sup> molec cm<sup>−2</sup>,
with a mean VCD of 17.4 ± 3.7 × 10<sup>15</sup> molec cm<sup>−2</sup>. In the Brussels area, smaller levels are found, ranging
between 1 and 20 × 10<sup>15</sup> molec cm<sup>−2</sup> and a mean VCD of 7.7 ± 2.1 × 10<sup>15</sup> molec cm<sup>−2</sup>.
The overall errors on the retrieved NO<sub>2</sub>
VCDs are on average 21 and 28 % for the Antwerp and Brussels data sets. Low VCD retrievals are mainly limited by noise (1<i>σ</i> slant
error), while high retrievals are mainly limited by systematic errors.
Compared to coincident car mobile-DOAS measurements taken in Antwerp and
Brussels, both data sets are in good agreement with correlation coefficients
around 0.85 and slopes close to unity. APEX retrievals tend to be, on
average, 12 and 6 % higher for Antwerp and Brussels, respectively. Results
demonstrate that the NO<sub>2</sub> distribution in an urban environment, and its
fine-scale variability, can be mapped accurately with high spatial resolution
and in a relatively short time frame, and the contributing emission sources
can be resolved. High-resolution quantitative information about the
atmospheric NO<sub>2</sub> horizontal variability is currently rare, but
can be very valuable for (air quality) studies at the urban scale. |
| first_indexed | 2024-04-12T01:22:09Z |
| format | Article |
| id | doaj.art-c4517cd5a08644a9a0e865c3f01ce3e2 |
| institution | Directory Open Access Journal |
| issn | 1867-1381 1867-8548 |
| language | English |
| last_indexed | 2024-04-12T01:22:09Z |
| publishDate | 2017-05-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Measurement Techniques |
| spelling | doaj.art-c4517cd5a08644a9a0e865c3f01ce3e22022-12-22T03:53:46ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482017-05-011051665168810.5194/amt-10-1665-2017High-resolution mapping of the NO<sub>2</sub> spatial distribution over Belgian urban areas based on airborne APEX remote sensingF. Tack0A. Merlaud1M.-D. Iordache2T. Danckaert3H. Yu4C. Fayt5K. Meuleman6F. Deutsch7F. Fierens8M. Van Roozendael9BIRA-IASB, Royal Belgian Institute for Space Aeronomy, Brussels, 1180, BelgiumBIRA-IASB, Royal Belgian Institute for Space Aeronomy, Brussels, 1180, BelgiumVITO, Flemish Institute for Technological Research, Mol, 2400, BelgiumBIRA-IASB, Royal Belgian Institute for Space Aeronomy, Brussels, 1180, BelgiumBIRA-IASB, Royal Belgian Institute for Space Aeronomy, Brussels, 1180, BelgiumBIRA-IASB, Royal Belgian Institute for Space Aeronomy, Brussels, 1180, BelgiumVITO, Flemish Institute for Technological Research, Mol, 2400, BelgiumVITO, Flemish Institute for Technological Research, Mol, 2400, BelgiumIRCEL-CELINE, Belgian Interregional Environment Agency, Brussels, 1210, BelgiumBIRA-IASB, Royal Belgian Institute for Space Aeronomy, Brussels, 1180, BelgiumWe present retrieval results of tropospheric nitrogen dioxide (NO<sub>2</sub>) vertical column densities (VCDs), mapped at high spatial resolution over three Belgian cities, based on the DOAS analysis of Airborne Prism EXperiment (APEX) observations. APEX, developed by a Swiss-Belgian consortium on behalf of ESA (European Space Agency), is a pushbroom hyperspectral imager characterised by a high spatial resolution and high spectral performance. APEX data have been acquired under clear-sky conditions over the two largest and most heavily polluted Belgian cities, i.e. Antwerp and Brussels on 15 April and 30 June 2015. Additionally, a number of background sites have been covered for the reference spectra. The APEX instrument was mounted in a Dornier DO-228 aeroplane, operated by Deutsches Zentrum für Luft- und Raumfahrt (DLR). NO<sub>2</sub> VCDs were retrieved from spatially aggregated radiance spectra allowing urban plumes to be resolved at the resolution of 60 × 80 m<sup>2</sup>. The main sources in the Antwerp area appear to be related to the (petro)chemical industry while traffic-related emissions dominate in Brussels. The NO<sub>2</sub> levels observed in Antwerp range between 3 and 35 × 10<sup>15</sup> molec cm<sup>−2</sup>, with a mean VCD of 17.4 ± 3.7 × 10<sup>15</sup> molec cm<sup>−2</sup>. In the Brussels area, smaller levels are found, ranging between 1 and 20 × 10<sup>15</sup> molec cm<sup>−2</sup> and a mean VCD of 7.7 ± 2.1 × 10<sup>15</sup> molec cm<sup>−2</sup>. The overall errors on the retrieved NO<sub>2</sub> VCDs are on average 21 and 28 % for the Antwerp and Brussels data sets. Low VCD retrievals are mainly limited by noise (1<i>σ</i> slant error), while high retrievals are mainly limited by systematic errors. Compared to coincident car mobile-DOAS measurements taken in Antwerp and Brussels, both data sets are in good agreement with correlation coefficients around 0.85 and slopes close to unity. APEX retrievals tend to be, on average, 12 and 6 % higher for Antwerp and Brussels, respectively. Results demonstrate that the NO<sub>2</sub> distribution in an urban environment, and its fine-scale variability, can be mapped accurately with high spatial resolution and in a relatively short time frame, and the contributing emission sources can be resolved. High-resolution quantitative information about the atmospheric NO<sub>2</sub> horizontal variability is currently rare, but can be very valuable for (air quality) studies at the urban scale.http://www.atmos-meas-tech.net/10/1665/2017/amt-10-1665-2017.pdf |
| spellingShingle | F. Tack A. Merlaud M.-D. Iordache T. Danckaert H. Yu C. Fayt K. Meuleman F. Deutsch F. Fierens M. Van Roozendael High-resolution mapping of the NO<sub>2</sub> spatial distribution over Belgian urban areas based on airborne APEX remote sensing Atmospheric Measurement Techniques |
| title | High-resolution mapping of the NO<sub>2</sub> spatial distribution over Belgian urban areas based on airborne APEX remote sensing |
| title_full | High-resolution mapping of the NO<sub>2</sub> spatial distribution over Belgian urban areas based on airborne APEX remote sensing |
| title_fullStr | High-resolution mapping of the NO<sub>2</sub> spatial distribution over Belgian urban areas based on airborne APEX remote sensing |
| title_full_unstemmed | High-resolution mapping of the NO<sub>2</sub> spatial distribution over Belgian urban areas based on airborne APEX remote sensing |
| title_short | High-resolution mapping of the NO<sub>2</sub> spatial distribution over Belgian urban areas based on airborne APEX remote sensing |
| title_sort | high resolution mapping of the no sub 2 sub spatial distribution over belgian urban areas based on airborne apex remote sensing |
| url | http://www.atmos-meas-tech.net/10/1665/2017/amt-10-1665-2017.pdf |
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