Review of Comprehensive Measurements of Speciated NOy and its Chemistry: Need for Quantifying the Role of Heterogeneous Processes of HNO3 and HONO

Hajime Akimoto,Hiroshi Tanimoto

doi:10.4209/aaqr.2020.07.0395

Hajime Akimoto, Hiroshi Tanimoto

Open Access

https://doi.org/10.4209/aaqr.2020.07.0395

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Abstract

ABSTRACT To improve the credibility of chemistry schemes employed in chemical transport models (CTMs) aiming at predicting ozone mixing ratios in urban, rural, and regional scales, validation of models not only by observational data of O3 and NOx but also by individual species of reactive nitrogen NOy is necessary because the formation and dissipation of O3 in the atmosphere occur via reactions accompanying the transformation of NOx and NOy. The disagreement of the simulated results of CTM with observational data of HNO3 and HONO have often been reported, and this paper reviews previous studies on the heterogeneous “renoxification” reaction of gaseous HNO3 to form NO, NO2, and/or HONO; the formation of HONO from the heterogeneous dark reaction of NO2 and H2O, and the photolysis of adsorbed HNO3 and NO3– on surfaces. For the further validation of CTMs with individual species of NOy, previous field studies of comprehensive observation of NOy speciation in ground-based and aircraft campaigns have also been reviewed. Studies combining observations of speciated NOy and model simulations need to be performed to improve chemistry models used in CTMs.

Highlights

Received: July 13, 2020 Revised: November 1, 2020 Accepted: November 2, 2020Publisher: Taiwan Association for Aerosol Research ISSN: 1680-8584 print ISSN: 2071-1409 onlineCopyright: The Author(s)
Among the species consisting NOy, nitrogen oxides (NOx) (NO and NO2) are the major components followed by peroxyacetyl nitrate (PAN), HNO3 and HONO in typical polluted urban air
In the recent MICS-Asia III project, overestimation of O3 associated with the underestimation of NOx in the urban areas of Beijing and Tokyo in July has been noted for the selected models of CMAQ (Community Multiscale Air Quality Modeling System) v.4.7.1 and v.5.0.2, whereas better agreement between the modeling results and observational data was seen for the NAQPMS (Nested Air Quality Prediction Modeling System) (Akimoto et al, 2019)

Summary

INTRODUCTION

Publisher: Taiwan Association for Aerosol Research ISSN: 1680-8584 print ISSN: 2071-1409 online. An international model intercomparison project, MICS-Asia III (Model Intercomparison Study for Asia Phase III), was conducted with a particular emphasis on the East Asian region This project revealed that, despite using common precursor emissions, meteorological field, and boundary conditions, the simulated surface O3 and NOx concentrations among various models and between models and observations disagree seriously (Li et al, 2019). This prompted us to elucidate the causes of disagreements to improve the credibility of CTMs (Akimoto et al, 2019). In order to reduce the uncertainty of chemical schemes in CTMs, we discuss the importance of atmospheric heterogeneous chemistry of nitrogenous species, and review previous field studies of comprehensive observation of reactive nitrogen (hereafter NOy) species, aiming at a future proposal of a new observational campaign for comprehensive NOy measurements to validate the chemistry schemes of CTMs

RESULTS AND DISCUSSION

Comprehensive Observation of NOy Speciation and Chemistry

CONCLUSIONS