Impacts of Chemical and Synoptic Processes on Summer Tropospheric Ozone Trend in North China

Abstract

Compared with other regions in China, air pollution on the North China Plain (NCP) is serious. Fine particle pollution has been studied in-depth, but there is less research on long-term troposphere ozone (O 3 ) variation. is study focuses on the summer interannual tropospheric O 3 variation on the NCP and its influential factors. Our analysis relies on satellite observations (O 3 , nitrogen dioxide (NO 2 ), sulfur dioxide (SO 2 ), carbon monoxide (CO), and formaldehyde (HCHO), determined as vertical column density of the troposphere) and dynamical processes (El Niño-Southern Oscillation (ENSO), potential vorticity (PV), the quasibiennial oscillation (QBO), and East Asian summer monsoon index (EASMI)). Our results show the vertical column density of tropospheric O 3 has a transition from the increasing trend to decreasing trend during the summer of 2005-2016. e summer series of tropospheric O 3 show two distinct phases: the first phase (2005)(2006)(2007)(2008)(2009)(2010)(2011), with an average growth rate of 0.55 ± 0.20 DU/yr, and a second phase (2012)(2013)(2014)(2015)(2016), with an average reduction rate of 0.16 ± 0.23 DU/yr. e tropospheric NO 2 column in the NCP also has a transition from the increasing trend to decreasing trend during the summer of 2005-2016. Tropospheric NO 2 and CO column concentrations obtained from satellite observations indicate that emission reductions might be the main cause of the tropospheric O 3 decrease. Particularly, the reduction of nitrogen oxides (NO x ) is more significant, and NO 2 decreased by (0.45 ± 0.11) × 10 15 molec·cm − 2 per year in summer since 2012. However, tropospheric column HCHO shows an increase of 0.05 × 10 15 molec·cm − 2 per year during the whole period of 2005 to 2016. An O 3 -NO x -VOC sensitivity experiment in the NCP showed that the O 3 is still in a NO x -saturated state in some heavily polluted cities, although the NO x emissions are decreasing overall. In addition to the chemical reactions, atmospheric dynamic processes also have an effect on tropospheric O 3 . Finally, we built a model to analyze the contributions of chemical processes and dynamic processes to the tropospheric O 3 column in the NCP. For the chemical process variables, 69.73% of the observed trend of tropospheric O 3 could be explained by the NO 2 tropospheric column. erefore, the reduction of tropospheric O 3 since 2012 is associated with the reduction of NOx. For the dynamical process variables, ENSO, PV, and EASMI can explain 60.64% of the observed trend of tropospheric O 3 . is result indicates that the atmospheric circulation of the western Pacific Ocean in summer has a significant impact on the interannual trends of tropospheric O 3 in the NCP. It is also found that chemical processes had a more important impact on interannual tropospheric O 3 than dynamic processes, although the dynamic processes cannot be neglected.

Spatial patterns of torrential rain in the Haihe River Basin and the corresponding large‐scale circulation

“…At midlatitudes, the WPSH extends roughly 5° westward and 10° northward relative to the climatological mean position, forming high‐pressure anomalies near the Korean Peninsula. Previous studies have found that precipitation generally occurs 6°–10° north of the WPSH ridge line (Zhu, 2007), which is consistent with the precipitation centre of Type 1.…”

Atmospheric Hydrogen Peroxide (H2O2) at the Foot and Summit of Mt. Tai: Variations, Sources and Sinks, and Implications for Ozone Formation Chemistry

“…Zhou et al. (2019) found that tropospheric column HCHO from satellite observations, which is indicative of the change of reactive VOCs, showed an increase of 0.05 × 10 15 molecules cm −2 yr −1 during the whole period from 2005 to 2016 in the NCP. Therefore, the remarkable increase of H 2 O 2 from 2007 to 2019 at the summit of Mt.…”

Analysis of Heavy Precipitation Event in Northeast China from August 1 to 5, 2023

“…It mainly analyzes the changes of weather through describing various phenomena and processes in the atmosphere, such as fronts, cyclones, and troughs. This method particularly emphasizes the study of weather phenomena and processes that play an important role in weather evolution (Santurette & Georgiev, 2005;Zhu et al, 2007). In this study, the synoptic meteorology method was used to deeply explore the formation conditions, circulation background, and their interactions of heavy rain, providing a scientific basis for us to better understand the heavy rain process.…”