Elucidating the effect of HONO on O3 pollution by a case study in southwest China

Thermal dissociation cavity-enhanced absorption spectrometer for measuring NO<sub>2</sub>, RO<sub>2</sub>NO<sub>2</sub>, and RONO<sub>2</sub> in the atmosphere

“…The CEAS system has been described in detail in previous literature (Duan et al, 2018;Fiedler et al, 2003;Jordan and Osthoff, 2020;Jordan et al, 2019;Langridge et al, 2006;Liang et al, 2019;Liu et al, 2019;Min et al, 2016;Tang et al, 2020;Ventrillard-Courtillot et al, 2010;Yi et al, 2016); thus there is a brief introduction to the principle of the instrument here. NO 2 molecules have a specific absorption structure in the wavelength range of 430-460 nm (Fig.…”

Reply on RC1

“…TD-CEAS has deployed the first field observation in Xinjin County, Chengdu, China, in 2019, referred to as the CHOOSE campaign (Yang et al, 2020). As shown in Fig.…”

The Lack of HONO Measurement May Affect the Accurate Diagnosis of Ozone Production Sensitivity

“…However, to our knowledge, continuous HONO measurements in China were mostly performed in megacities such as Beijing, 20,26−28 Shanghai, 29−32 Guangzhou, 33−35 and Hong Kong 36−38 at present, and only a few focused on the second-and third-tier cities (e.g., Chengdu, Tai'an, Ji'nan, Baoding) during the summer O 3 pollution period. 18,22,39 The absence of HONO observation not only influences the evaluation of atmospheric oxidation capacity, 19 In this study, a comprehensive field campaign was performed in a typical urban site (Tai'an) of the NCP during the summer of 2018, and the impacts of atmospheric HONO on the O 3 budget and O 3 -NO x -VOC sensitivity regime were explicitly explored to provide some insights for O 3 control strategies based on the sensitivity tests in a photochemical box model.…”

“…Many studies have proposed that atmospheric HONO acting as a dominant precursor of OH radicals − makes a great contribution to O 3 formation, − whereas its sources are not fully understood. , As a result, HONO formation in the default box model was only regarded to be from the homogeneous reaction of NO with OH radicals, , leading to a visible underestimation of HONO levels. Although the gap between simulated and observed HONO concentrations could be significantly narrowed through incorporating other known sources including direct emission, heterogeneous conversion of NO 2 , and so on into the model, ,, some key HONO-related kinetic parameters in the model are often changed optionally in order to be closer to the observation.…”

“…For example, the uptake coefficient of NO 2 on surfaces could vary from 2 × 10 –7 to 1 × 10 –5 . − Therefore, the high uncertainties of the HONO simulation in the box model highlighted the significance of the HONO observation-based constraint. However, to our knowledge, continuous HONO measurements in China were mostly performed in megacities such as Beijing, ,− Shanghai, − Guangzhou, − and Hong Kong − at present, and only a few focused on the second- and third-tier cities (e.g., Chengdu, Tai’an, Ji’nan, Baoding) during the summer O 3 pollution period. ,, The absence of HONO observation not only influences the evaluation of atmospheric oxidation capacity, but also is likely to provide a misleading diagnosis for O 3 sensitivity regimes. Although the effect of initial HONO on the sensitivity of O 3 production in Los Angeles was preliminarily assessed in 1982 based on a simplified trajectory model, the accuracy of HONO measurement and the understanding of chemical mechanisms at that time are outdated.…”