Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2021 Jan:262:127595.
doi: 10.1016/j.chemosphere.2020.127595. Epub 2020 Jul 10.

Effect of bromine and iodine chemistry on tropospheric ozone over Asia-Pacific using the CMAQ model

Yeqi Huang  1 , Xingcheng Lu  1 , Jimmy C H Fung  2 , Golam Sarwar  3 , Zhenning Li  4 , Qinyi Li  5 , Alfonso Saiz-Lopez  5 , Alexis K H Lau  6
Affiliations

Effect of bromine and iodine chemistry on tropospheric ozone over Asia-Pacific using the CMAQ model

Yeqi Huang et al. Chemosphere. 2021 Jan.

Abstract

Recent studies have focused on the chemistry of tropospheric halogen species which are able to deplete tropospheric ozone (O3). In this study, the effect of bromine and iodine chemistry on tropospheric O3 within the annual cycle in Asia-Pacific is investigated using the CMAQ model with the newly embedded bromine and iodine chemistry and a blended and customized emission inventory considering marine halogen emission. Results indicate that the vertical profiles of bromine and iodine species show distinct features over land/ocean and daytime/nighttime, related to natural and anthropogenic emission distributions and photochemical reactions. The halogen-mediated O3 loss has a strong seasonal cycle, and reaches a maximum of -15.9 ppbv (-44.3%) over the ocean and -13.4 ppbv (-38.9%) over continental Asia among the four seasons. Changes in solar radiation, dominant wind direction, and nearshore chlorophyll-a accumulation all contribute to these seasonal differences. Based on the distances to the nearest coastline, the onshore and offshore features of tropospheric O3 loss caused by bromine and iodine chemistry are studied. Across a coastline-centric 400-km-wide belt from onshore to offshore, averaged maximum gradient of O3 loss reaches 1.1 ppbv/100 km at surface level, while planetary boundary layer (PBL) column mean of O3 loss is more moderate, being approximately 0.7 ppbv/100 km. Relative high halogen can be found over Tibetan Plateau (TP) and the largest O3 loss (approximately 4-5 ppbv) in the PBL can be found between the western boundary of the domain and the TP. Halogens originating from marine sources can potentially affect O3 concentration transported from the stratosphere over the TP region. As part of efforts to improve our understanding of the effect of bromine and iodine chemistry on tropospheric O3, we call for more models and monitoring studies on halogen chemistry and be considered further in air pollution prevention and control policy.

Keywords: Bromine and iodine chemistry; CMAQ; Onshore/offshore features; Tropospheric O(3); Vertical structure.

PubMed Disclaimer

Conflict of interest statement

Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Figure 1
Figure 1
Vertical profiles of model-simulated bromine species (a–d) over land during daytime (7:00–17:00), (e–h) over the ocean during daytime (7:00–17:00). (i–l) Same as (a–h) but during nighttime (21:00−5:00) in four seasons. The vertical axes are the altitude (unit: m) and horizontal axes are pollutant concentration (unit: ppbv).
Figure 2
Figure 2
Same as Figure 1 but for iodine species (pptv).
Figure 3
Figure 3
(a–d) Shaded areas show monthly mean of surface Br mixing ratios (pptv) in four representative months for the HAL simulation. (e–h) same as (a–d) but for BrO. (i–l) same as (a–d) but for I. (m–p) same as (a–d) but for IO.
Figure 4
Figure 4
(a–d) Shaded areas show monthly mean values of the daily maximum 8-h average (MDA8) surface O3 mixing ratios (ppbv) in four representative months, with the HAL simulation. (e–h) Absolute difference of MDA8 between the two simulations (HAL-BASE). (i–l) Percent difference of MDA8 between the two simulations [(HAL − BASE)/BASE × 100%].
Figure 5
Figure 5
(a) Blue (red) curve shows the gridded mean difference of surface (PBL column mean) MDA8 O3 mixing ratio (HAL − BASE, unit: ppbv) for January as a function of the distance to the nearest coast. Distances > 0 indicate the target grid point is at sea, whereas distances < 0 indicate it is on land. The black dashed line denotes the coast. The shaded area denotes the ±1 standard deviation range of the gridded O3 mixing ratio. The PBL column mean is calculated from the surface to approximately 1500 m above the surface (the 19th model layer). (b–d) Same as (a) but for April, July, and October.
Figure 6
Figure 6
(a) Shaded areas denote the gridded monthly mean difference of MDA8 O3 mixing ratio (ppbv) (HAL − BASE) for January as a function of height and the distance to the nearest coast. (b–d) Same as (a) but for April, July, and October.
Figure 7
Figure 7
(a) Cross-section plot of January monthly mean of MDA8 O3 mixing ratios (ppbv) along the blue curve in Figure S9. (b) Same as (a), but for the difference in O3 mixing ratio (ppbv; HAL − BASE). (c) Same as (a), but for BrO (ppbv) as an example, and overlaid vectors (unit: m/s) are for monthly mean vertical velocity filed.
See this image and copyright information in PMC

References

    1. Angevine WM, Senff CJ, White AB, Williams EJ, Koermer J, Miller ST, Talbot R, Johnston PE, McKeen SA and Downs T, 2004. Coastal boundary layer influence on pollutant transport in New England. Journal of Applied Meteorology, 43(10), pp.1425–1437.
    1. Chen X, Anel JA, Su Z, de la Torre L, Kelder H, van Peet J and Ma Y, 2013. The deep atmospheric boundary layer and its significance to the stratosphere and troposphere exchange over the Tibetan Plateau. PloS one, 8(2), p.e56909. - PMC - PubMed
    1. Crippa M, Guizzardi D, Muntean M, Schaaf E, Dentener F, van Aardenne JA, Monni S, Doering U, Olivier JG, Pagliari V and Janssens-Maenhout G, 2018. Gridded emissions of air pollutants for the period 1970–2012 within EDGAR v4.3.2. Earth System Science Data, 10(4), pp.1987–2013.
    1. Gantt B, Kelly JT and Bash JO, 2015. Updating sea spray aerosol emissions in the Community Multiscale Air Quality (CMAQ) model version 5.0.2. Geoscientific Model Development Discussions, 8(5).
    1. Gantt B, Sarwar G, Xing J, Simon H, Schwede D, Hutzell WT, Mathur R and Saiz-Lopez A, 2017. The impact of iodide-mediated ozone deposition and halogen chemistry on surface ozone concentrations across the continental United States. Environmental science & technology, 51(3), pp.1458–1466. - PMC - PubMed