High-resolution mapping of the NO<sub>2</sub> spatial distribution over Belgian urban areas based on airborne APEX remote sensing
-
Published:2017-05-04
Issue:5
Volume:10
Page:1665-1688
-
ISSN:1867-8548
-
Container-title:Atmospheric Measurement Techniques
-
language:en
-
Short-container-title:Atmos. Meas. Tech.
Author:
Tack Frederik,Merlaud Alexis,Iordache Marian-Daniel,Danckaert Thomas,Yu Huan,Fayt Caroline,Meuleman Koen,Deutsch Felix,Fierens Frans,Van Roozendael Michel
Abstract
Abstract. We present retrieval results of tropospheric nitrogen dioxide (NO2) 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). NO2 VCDs were retrieved from spatially aggregated radiance spectra allowing urban plumes to be resolved at the resolution of 60 × 80 m2. The main sources in the Antwerp area appear to be related to the (petro)chemical industry while traffic-related emissions dominate in Brussels. The NO2 levels observed in Antwerp range between 3 and 35 × 1015 molec cm−2, with a mean VCD of 17.4 ± 3.7 × 1015 molec cm−2. In the Brussels area, smaller levels are found, ranging between 1 and 20 × 1015 molec cm−2 and a mean VCD of 7.7 ± 2.1 × 1015 molec cm−2. The overall errors on the retrieved NO2 VCDs are on average 21 and 28 % for the Antwerp and Brussels data sets. Low VCD retrievals are mainly limited by noise (1σ 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 NO2 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 NO2 horizontal variability is currently rare, but can be very valuable for (air quality) studies at the urban scale.
Funder
Belgian Federal Science Policy Office
Publisher
Copernicus GmbH
Subject
Atmospheric Science
Reference70 articles.
1. Anderson, G., Clough, S., Kneizys, F., Chetwynd, J., and Shettle, E.: AFGL atmospheric constituent profiles (0–120km), Hanscom AFB, MA: Optical Physics Division, Air Force Geophysics Laboratory, AFGL-TR; 86-0110, US Air Force Geophysics Laboratory, Optical Physics Division, 1, 1986. 2. Baidar, S., Oetjen, H., Coburn, S., Dix, B., Ortega, I., Sinreich, R., and Volkamer, R.: The CU Airborne MAX-DOAS instrument: vertical profiling of aerosol extinction and trace gases, Atmos. Meas. Tech., 6, 719–739, https://doi.org/10.5194/amt-6-719-2013, 2013. 3. Beirle, S., Kühl, S., Pukite, J., and Wagner, T.: Retrieval of tropospheric column densities of NO2 from combined SCIAMACHY nadir/limb measurements, Atmos. Meas. Tech., 3, 283–299, https://doi.org/10.5194/amt-3-283-2010, 2010. 4. Beirle, S., Lampel, J., Lerot, C., Sihler, H., and Wagner, T.: Parameterizing the instrumental spectral response function and its changes by a super-Gaussian and its derivatives, Atmos. Meas. Tech., 10, 581–598, https://doi.org/10.5194/amt-10-581-2017, 2017. 5. Berk, A., Andersonm, G.P., Bernstein, L., Acharya, P., Dothe, H., Matthew, M., Adler-Golden, S., Chetwynd Jr., J., Richtsmeier, S., Brian Pukall, B., Allred, C., Jeong, L., and Hoke, M.: MODTRAN4 radiative transfer modeling for atmospheric correction, in: Proceedings SPIE 3756, Optical Spectroscopic Techniques and Instrumentation for Atmospheric and Space Research III, Denver, CO, USA, 18 July, 1999.
Cited by
21 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献
|
|