Hajime Akimoto This email address is being protected from spambots. You need JavaScript enabled to view it., Hiroshi Tanimoto

National Institute for Environmental Studies, Tsukuba, Ibaraki, 305-8506, Japan


Received: July 13, 2020
Revised: November 1, 2020
Accepted: November 2, 2020

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

Download Citation: ||https://doi.org/10.4209/aaqr.2020.07.0395  

  • Download: PDF

Cite this article:

Akimoto, H., Tanimoto, H. (2021). Review of Comprehensive Measurements of Speciated NOy and its Chemistry: Need for Quantifying the Role of Heterogeneous Processes of HNO3 and HONO. Aerosol Air Qual. Res. 21, 200395. https://doi.org/10.4209/aaqr.2020.07.0395


  • The atmospheric heterogeneous processes related to HNO3 and HONO have been reviewed.
  • Previous studies on comprehensive observations of NOy speciation have been reviewed.
  • Evaluation of CTMs for observed speciated NOy species needs to be conducted.


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.

Keywords: Reactive nitrogen, Nitric acid, Nitrous acid, Ozone, Chemical transport model

Don't forget to share this article 


Subscribe to our Newsletter 

Aerosol and Air Quality Research has published over 2,000 peer-reviewed articles. Enter your email address to receive latest updates and research articles to your inbox every second week.

Latest coronavirus research from Aerosol and Air Quality Research

2018 Impact Factor: 2.735

5-Year Impact Factor: 2.827

Aerosol and Air Quality Research (AAQR) is an independently-run non-profit journal, promotes submissions of high-quality research, and strives to be one of the leading aerosol and air quality open-access journals in the world.