Estimation of the Paris NO<sub><i>x</i></sub> emissions from mobile MAX-DOAS observations and CHIMERE model simulations during the MEGAPOLI campaign using the closed integral method

Abstract

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 (http://megapoli.dmi.dk/). 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 × 3 km2) 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 × 1025 molec s−1 for summer and of 6.9 × 1025 molec s−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.

Soccer games and record-breaking PM<sub>2.5</sub> pollution events in Santiago, Chile

“…1, with a coarse domain at a 15 km spatial resolution comprising most of Chile and a nested domain focusing on central Chile and centered on Santiago at a 3 km resolution. The meteorological conditions are simulated using the WRF model from the US National Center for Atmospheric Research (Skamarock et al, 2008). The model configuration used in this study to simulate and reproduce observed meteorological conditions is presented in Table 1.…”

“…Mazzeo et al (2018) used a similar setup with a 2 km resolution for a sensitivity analysis of traffic and residential heating emissions in Santiago, yielding similar performances. Comparable CHIMERE simulations are performed for purposes of air quality operational forecast in France, whose performance at a small scale is acknowledged in the literature, provided emissions have appropriate magnitudes (Petit et al, 2017;Shaiganfar et al, 2017). Table 3.…”

“…The termination of one of these events is studied hereafter. A chemistry-transport simulation is run with WRF (Skamarock et al, 2008) and CHIMERE for the austral winter 2016 (see Sect. 2 for the details).…”

Low modeled ozone production suggests underestimation of precursor emissions (especially NO<sub><i>x</i></sub>) in Europe

“…Furthermore, Vaughan et al (2016) and Karl et al (2017) reached similar conclusions by analyzing NO x flux measurements and attributed the discrepancy between observations and emission inventory estimates to the underrepresentation of the real-world road traffic emissions. Moreover, a general underestimation of the total NO x emissions, compared to TNO MEGAPOLI and MACC-III inventories, by a factor of 1.4-1.5 for the summer of 2009 in Paris was recently reported by Shaiganfar et al (2017), where they used a large set of car multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements to calculate the NO x emissions by applying the closed integral method (CIM). For the VOC emissions, there are reported emission uncertainties of ∼ 50 % for the anthropogenic sources (Theloke and Friedrich, 2007;Kuenen et al, 2014).…”

Tropospheric NO<sub>2</sub>, SO<sub>2</sub>, and HCHO over the East China Sea, using ship-based MAX-DOAS observations and comparison with OMI and OMPS satellite data

“…The most common application is ground-based measurement (e.g., Irie et al, 2011;Pinardi et al, 2013;Wang et al, 2014;Chan et al, 2015;Xing et al, 2017). Meanwhile, mobile platform observations have been developed rapidly, e.g., carbased observations (Johansson et al, 2008;Shaiganfar et al, 2011Shaiganfar et al, , 2017Wang et al, 2012), aircraft observations (Baidar et al, 2013;Dix et al, 2016), and ship-based observations (Sinreich et al, 2010;Takashima et al, 2012;Peters et al, 2012;Schreier et al, 2015;Hong et al, 2018).…”