Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2024 Sep 6;7(1):207. doi: 10.1038/s41612-024-00747-6

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

© The Author(s) 2024

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

PMC Copyright notice

Fig. 2 — A Directly emitted primary OA, OOA formed from photo-oxidation (LO-OOA and MO-OOA) and nocturnal oxidation processes (NO-OOA) resolved by the PMF analysis of particulate nitrate and organic aerosol measurements during the JULIAC campaign. The ratio of the ion mass signals of the fragments CO₂⁺ (fCO₂⁺) vs the sum of NO⁺ and NO₂⁺ (f(NO⁺ + NO₂⁺)) normalized to the total ion mass signal intensity is used to show the distribution of nitrate-containing OA factors. These OA factors fall in fCO₂⁺ vs f(NO⁺ + NO₂⁺) space and are represented by gray circles and categorized by the grey, dark green, and light green rectangles respectively, with a detailed graph in Supplementary Fig. 25. The value of f(NO⁺ + NO₂⁺) (<0.04) of primary OA and photo-oxidation OOA is marked as background by a red dashed line. B The ratio of nitrate fragments (NO₂⁺/NO⁺) in NO-OOA across seasons is shown by green markers with line, while blue markers with line represent the ratio of inorganic ammonium nitrate particles (NH₄NO₃). The blue dashed line represents the reference ratio of pure organic nitrate²⁴. C The chemical composition, characterized mass spectrum characteristics of f44 vs f60, is used to compare the averaged PMF factors from this study (shown as circle with error bar) to those from previous field studies^9,20,52,53 (depicted as rectangles). These studies all identified an unexplained nocturnal OOA, daytime OOA, and primary BBOA, highlighted by light green, dark green, and brown rectangles, respectively. Detailed factor positions are provided in Supplementary Fig. 25. The background value of f60 (~0.3%) for atmospheric OA^87,88 is marked by a red dashed line. Additionally, (D) compares the averaged OA factors obtained in this study to the OA evolution during the dark oxidation of biomass-burning emission by NO₃· in a chamber study^87,88, illustrated with dotted line color-coded by aging time. The seasonal averaged diurnal pattern of the mass concentration of the NO-OOA, BBOA, NO₃·, and SOA production rate of the NO₃· reaction with monoterpenes and isoprene are shown for summer (E) and spring (F). The grey areas represent nighttime.