Effects of synoptic patterns on the vertical structure of ozone in Hong Kong using lidar measurement

Lin, Changqing; Leung, Kenneth K. M.; Yu, Alfred L.C.; Tsang, Roy C.W.; Tsui, Wilson; Fung, Jimmy Chi Hung; Ng, Eric K. W.; Cheung, S.L.; Tang, Alice W.Y.; Ning, Zhi; Lau, Alexis Kai Hon

doi:10.1016/j.atmosenv.2021.118490

Cited by 14 publications

(7 citation statements)

References 45 publications

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“…Meanwhile, it is noticed that high O3 mixing ratios appear within the atmospheric boundary layer (ABL) (0.7-1.6km according to Su et al, (2017)) in Hong Kong in autumn (Figure 2a), which represents the combined effect of local emissions and regional transport. During this season, the prevailing winds are predominantly from northwest to north, which could bring elevated levels of O3 and its precursors from the Pearl River Delta region, a major manufacturing base in China, to Hong Kong (Ding et al, 2013;Lin et al, 2021). the summer and at Tsukuba (0.63 ppb a -1 ) during the spring (at a 95% confidence level).…”

Section: Climatological Distribution Of Tropospheric Ozonementioning

confidence: 99%

Causes of growing middle-upper tropospheric ozone over the Northwest Pacific region

Ma,

Huang,

Hegglin

et al. 2024

Preprint

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Abstract. Long-term ozone (O3) changes in the middle to upper troposphere are critical to climate radiative forcing and tropospheric O3 pollution. Yet, these changes remain poorly quantified through observations in East Asia. Concerns also persist regarding the data quality of the ozonesondes available at the World Ozone and Ultraviolet Data Center (WOUDC) for this region. This study aims to address these gaps by analyzing O3 soundings at four sites along the northwestern Pacific coastal region over the past three decades, and assessing their consistency with an atmospheric chemistry-climate model simulation. Utilizing the European Centre for Medium-Range Weather Forecasts (ECMWF) – Hamburg (ECHAM)/Modular Earth Submodel System (MESSy) Atmospheric Chemistry (EMAC) nudged simulations, it is demonstrated that trends between model and ozonesonde measurements are overall consistent, thereby gaining confidence in the model’s ability to simulate ozone trends and confirming the utility of potentially imperfect observational data. A notable increase in O3 mixing ratio around 0.29–0.82 ppb a-1 extending from the middle to upper troposphere is observed in both observations and model simulations between 1990 and 2020, primarily during spring and summer. The timing of these O3 hotspots is delayed when moving from south to north along the measurement sites, transitioning from late spring to summer. Investigation into the drivers of these trends using tagged model tracers reveals that ozone of stratospheric origin (O3S) dominates the absolute O3 mixing ratios over the middle-to-upper troposphere in the subtropics, contributing to the observed O3 increases by up to 96 % (40 %) during winter (summer), whereas ozone of tropospheric origin (O3T) governs the absolute value throughout the tropical troposphere and contributes generally much more than 60 % to the positive O3 changes, especially during summer and autumn. During winter and spring, a decrease of O3S is partly counterbalanced by an increase of O3T in the tropical troposphere. This study highlights that the enhanced downward transport of stratospheric O3 into the troposphere in the subtropics and a surge of tropospheric source O3 in the tropics are the two key factors driving the enhancement of O3 in the middle-upper troposphere along the Northwest Pacific region.

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Section: Climatological Distribution Of Tropospheric Ozonementioning

confidence: 99%

Causes of growing middle-upper tropospheric ozone over the Northwest Pacific region

Ma,

Huang,

Hegglin

et al. 2024

Preprint

View full text Add to dashboard Cite

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“…14 drawbacks such as high costs and observational blind spots within the range of a few hundred meters above the ground. 15 MAX-DOAS has found extensive applications in retrieving vertical profiles of aerosol and trace gases with concentrations primarily distributed within the troposphere. 16−19 However, due to the fact that stratospheric O 3 constitutes more than 90% of the total ozone, the traditional MAX-DOAS approach for O 3 profile retrieval is significantly affected by the non-negligible absorption from stratospheric O 3 .…”

Section: ■ Introductionmentioning

confidence: 99%

“…For ozone lidar, it enables routine vertical O 3 profile measurements spanning up to the tropopause, offering exceptional spatiotemporal resolution . However, lidar has drawbacks such as high costs and observational blind spots within the range of a few hundred meters above the ground …”

Section: Introductionmentioning

confidence: 99%

Stacking Machine Learning Models Empowered High Time-Height-Resolved Ozone Profiling from the Ground to the Stratopause Based on MAX-DOAS Observation

Zhang,

Wang,

Zhu

et al. 2024

Environ. Sci. Technol.

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Ozone (O3) profiles are crucial for comprehending the intricate interplay among O3 sources, sinks, and transport. However, conventional O3 monitoring approaches often suffer from limitations such as low spatiotemporal resolution, high cost, and cumbersome procedures. Here, we propose a novel approach that combines multiaxis differential optical absorption spectroscopy (MAX-DOAS) and machine learning (ML) technology. This approach allows the retrieval of O3 profiles with exceptionally high temporal resolution at the minute level and vertical resolution reaching the hundred-meter scale. The ML models are trained using parameters obtained from radiative transfer modeling, MAX-DOAS observations, and a reanalysis data set. To enhance the accuracy of retrieving the aqueous phosphorus from O3, we employ a stacking approach in constructing ML models. The retrieved MAX-DOAS O3 profiles are compared to data from an in situ instrument, lidar, and satellite observation, demonstrating a high level of consistency. The total error of this approach is estimated to be within 25%. On balance, this study is the first ground-based passive remote sensing of high time-height-resolved O3 distribution from ground to the stratopause (0–60 km). It opens up new avenues for enhancing our understanding of the dynamics of O3 in atmospheric environments. Moreover, the cost-effective and portable MAX-DOAS combined with this versatile profiling approach enables the potential for stereoscopic observations of various trace gases across multiple platforms.

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“…(2021) indicated that the stratospheric intrusions that frequently occur during spring, effectively transported cold air masses with high ozone from the lower stratosphere downwards into the upper troposphere over the North China Plain (NCP). In Hong Kong, it was previously reported that O 3 transported from southeastern or southern China affected the region when high‐pressure system and tropical cyclone prevailed (Lin et al., 2021). Moreover, the O 3 variation during 2015–2017 in eastern China was mainly associated with the north‐south movement of the subtropical high (H. Liu et al., 2021).…”

Section: Introductionmentioning

confidence: 99%

The Importance of NO_x Control for Peak Ozone Mitigation Based on a Sensitivity Study Using CMAQ‐HDDM‐3D Model During a Typical Episode Over the Yangtze River Delta Region, China

et al. 2022

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In recent years, ground‐level ozone (O3) has been one of the main pollutants hindering air quality compliance in China's large city‐clusters including the Yangtze River Delta (YRD) region. In this work, we utilized the process analysis (PA) and the higher‐order decoupled direct method (HDDM‐3D) tools embedded in the Community Multiscale Air Quality model (CMAQ) to characterize O3 formation and sensitivities to precursors during a typical O3 pollution episode over the YRD region in July 2018. Results indicate that gas‐phase chemistry contributed dominantly to the ground‐level O3 although a significant proportion was chemically produced at the middle and upper boundary layer before reaching the surface via diffusion process. Further analysis of the chemical pathways of O3 and Ox formation provided deep insights into the sensitivities of O3 to its precursors that were consistent with the HDDM results. The first‐order sensitivities of O3 to anthropogenic volatile organic compounds (AVOC) were mainly positive but small, and temporal variations were negligible compared with those to NOx. During the peak O3 time in the afternoon, the first‐ and second‐order sensitivities of O3 to NOx were significantly positive and negative, respectively, suggesting a convex response of O3 to NOx over most areas including Shanghai, Hangzhou, Nanjing and Hefei. These findings further highlighted an accelerated decrease in ground‐level O3 in the afternoon corresponding to continuous decrease of NOx emissions in the afternoon. Therefore, over the YRD region including its metropolises, NOx emission reductions will be more important in reducing the afternoon peak O3 concentration compared with the effect of VOC emission control alone.

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Effects of synoptic patterns on the vertical structure of ozone in Hong Kong using lidar measurement

Cited by 14 publications

References 45 publications

Causes of growing middle-upper tropospheric ozone over the Northwest Pacific region

Causes of growing middle-upper tropospheric ozone over the Northwest Pacific region

Stacking Machine Learning Models Empowered High Time-Height-Resolved Ozone Profiling from the Ground to the Stratopause Based on MAX-DOAS Observation

The Importance of NO_x Control for Peak Ozone Mitigation Based on a Sensitivity Study Using CMAQ‐HDDM‐3D Model During a Typical Episode Over the Yangtze River Delta Region, China

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Effects of synoptic patterns on the vertical structure of ozone in Hong Kong using lidar measurement

Cited by 14 publications

References 45 publications

Causes of growing middle-upper tropospheric ozone over the Northwest Pacific region

Causes of growing middle-upper tropospheric ozone over the Northwest Pacific region

Stacking Machine Learning Models Empowered High Time-Height-Resolved Ozone Profiling from the Ground to the Stratopause Based on MAX-DOAS Observation

The Importance of NOx Control for Peak Ozone Mitigation Based on a Sensitivity Study Using CMAQ‐HDDM‐3D Model During a Typical Episode Over the Yangtze River Delta Region, China

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The Importance of NO_x Control for Peak Ozone Mitigation Based on a Sensitivity Study Using CMAQ‐HDDM‐3D Model During a Typical Episode Over the Yangtze River Delta Region, China