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Satellite validation strategy assessments based on the AROMAT campaigns
oleh: A. Merlaud, L. Belegante, D.-E. Constantin, M. Den Hoed, A. C. Meier, M. Allaart, M. Ardelean, M. Arseni, T. Bösch, H. Brenot, A. Calcan, E. Dekemper, S. Donner, S. Dörner, M. C. Balanica Dragomir, L. Georgescu, A. Nemuc, D. Nicolae, G. Pinardi, A. Richter, A. Rosu, T. Ruhtz, A. Schönhardt, D. Schuettemeyer, R. Shaiganfar, K. Stebel, F. Tack, S. Nicolae Vâjâiac, J. Vasilescu, J. Vanhamel, T. Wagner, M. Van Roozendael
| Format: | Article |
|---|---|
| Diterbitkan: | Copernicus Publications 2020-10-01 |
Deskripsi
<p>The Airborne ROmanian Measurements of Aerosols and Trace gases (AROMAT) campaigns took place in Romania in September 2014 and August 2015. They focused on two sites: the Bucharest urban area and large power plants in the Jiu Valley. The main objectives of the campaigns were to test recently developed airborne observation systems dedicated to air quality studies and to verify their applicability for the validation of space-borne atmospheric missions such as the TROPOspheric Monitoring Instrument (TROPOMI)/Sentinel-5 Precursor (S5P). We present the AROMAT campaigns from the perspective of findings related to the validation of tropospheric <span class="inline-formula">NO<sub>2</sub></span>, <span class="inline-formula">SO<sub>2</sub></span>, and <span class="inline-formula">H<sub>2</sub>CO</span>. We also quantify the emissions of <span class="inline-formula">NO<sub><i>x</i></sub></span> and <span class="inline-formula">SO<sub>2</sub></span> at both measurement sites.</p> <p><span id="page5514"/>We show that tropospheric <span class="inline-formula">NO<sub>2</sub></span> vertical column density (VCD) measurements using airborne mapping instruments are well suited for satellite validation in principle. The signal-to-noise ratio of the airborne <span class="inline-formula">NO<sub>2</sub></span> measurements is an order of magnitude higher than its space-borne counterpart when the airborne measurements are averaged at the TROPOMI pixel scale. However, we show that the temporal variation of the <span class="inline-formula">NO<sub>2</sub></span> VCDs during a flight might be a significant source of comparison error. Considering the random error of the TROPOMI tropospheric <span class="inline-formula">NO<sub>2</sub></span> VCD (<span class="inline-formula"><i>σ</i></span>), the dynamic range of the <span class="inline-formula">NO<sub>2</sub></span> VCDs field extends from detection limit up to 37 <span class="inline-formula"><i>σ</i></span> (<span class="inline-formula">2.6×10<sup>16</sup></span> molec. cm<span class="inline-formula"><sup>−2</sup></span>) and 29 <span class="inline-formula"><i>σ</i></span> (2<span class="inline-formula">×10<sup>16</sup></span> molec. cm<span class="inline-formula"><sup>−2</sup></span>) for Bucharest and the Jiu Valley, respectively. For both areas, we simulate validation exercises applied to the TROPOMI tropospheric <span class="inline-formula">NO<sub>2</sub></span> product. These simulations indicate that a comparison error budget closely matching the TROPOMI optimal target accuracy of 25 % can be obtained by adding <span class="inline-formula">NO<sub>2</sub></span> and aerosol profile information to the airborne mapping observations, which constrains the investigated accuracy to within 28 %. In addition to <span class="inline-formula">NO<sub>2</sub></span>, our study also addresses the measurements of <span class="inline-formula">SO<sub>2</sub></span> emissions from power plants in the Jiu Valley and an urban hotspot of <span class="inline-formula">H<sub>2</sub>CO</span> in the centre of Bucharest. For these two species, we conclude that the best validation strategy would consist of deploying ground-based measurement systems at well-identified locations.</p>