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Volume 17, issue 12 | Copyright

Special issue: Megapoli-Paris 2009/2010 campaign

Atmos. Chem. Phys., 17, 7853-7890, 2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 29 Jun 2017

Research article | 29 Jun 2017

Estimation of the Paris NOx emissions from mobile MAX-DOAS observations and CHIMERE model simulations during the MEGAPOLI campaign using the closed integral method

Reza Shaiganfar1, Steffen Beirle1, Hugo Denier van der Gon2, Sander Jonkers2, Jeroen Kuenen2, Herve Petetin3, Qijie Zhang3, Matthias Beekmann3, and Thomas Wagner1 Reza Shaiganfar et al.
  • 1Max Planck Institute for Chemistry, Mainz, Germany
  • 2TNO, Climate, Air and Sustainability, Utrecht, the Netherlands
  • 3LISA/IPSL, UMR CNRS 7583, Université Paris Est Créteil et Université Paris Diderot, Créteil, France

Abstract. We determined NOx emissions from Paris in summer 2009 and winter 2009/2010 by applying the closed integral method (CIM) to a large set of car multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements performed within the framework of the MEGAPOLI project ( MAX-DOAS measurements of the tropospheric NO2 vertical column density (VCD) were performed in large circles around Paris. From the combination of the observed NO2 VCDs with wind fields, the NO2 influx into and the outflux from the encircled area was determined. The difference between the influx and outflux represents the total emission. Compared to previous applications of the CIM, the large number of measurements during the MEGAPOLI campaign allowed the investigation of important aspects of the CIM. In particular, the applicability of the CIM under various atmospheric conditions could be tested. Another important advantage of the measurements during MEGAPOLI is that simultaneous atmospheric model simulations with a high spatial resolution (3× 3km2) are available for all days. Based on these model data, it was possible to test the consistency of the CIM and to derive information about favourable or non-favourable conditions for the application of the CIM. We found that in most situations the uncertainties and the variability in the wind data dominate the total error budget, which typically ranges between 30 and 50%. Also, measurement gaps and uncertainties in the partitioning ratio between NO and NO2 are important error sources. Based on a consistency check, we deduced a set of criteria on whether measurement conditions are suitable or not for the application of the CIM. We also developed a method for the calculation of the total error budget of the derived NOx emissions. Typical errors are between ±30 and ±50% for individual days (with one full circle around Paris). From the application of the CIM to car MAX-DOAS observations we derive daily average NOx emissions for Paris of 4.0 × 1025molecs−1 for summer and of 6.9 × 1025molecs−1 in winter. These values are a factor of about 1.4 and 2.0 larger than the corresponding emissions derived from the application of the CIM to the model data, using the Toegepast Natuurwetenschappelijk Onderzoek (TNO) MEGAPOLI emission inventory, in summer and winter, respectively. Similar ratios (1.5 and 2.3 for summer and winter, respectively) were found for the comparison with the Monitoring Atmospheric composition and climate III (MACC-III) emission inventory. The highest NOx emissions were found during some cold days in February. Enhanced domestic heating and a reduced conversion efficiency of catalytic converters might contribute to these enhanced NOx emissions.

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We determine NOx emissions for Paris in summer 2009 and winter 2009/2010 by combining car MAX-DOAS measurements of NO2 with wind fields. We compare the results with simulations from the CHIMERE model. We derive daily average NOx emissions for Paris of 4.0 × 1025 molecules s−1 for summer and of 6.9 × 1025 molecules s−1 in winter. These values are a factor of about 1.4 and 2.0 larger than the corresponding emissions in the MACC-III emission inventory.
We determine NOx emissions for Paris in summer 2009 and winter 2009/2010 by combining car...