Recently, in China, during the period of transition between spring and summer, the combination of sandstorms and ozone (O₃) pollution has posed a significant challenge to the strategy of coordinated control of fine particulate matters (PM_2.5) and O₃. On the one hand, the dust invasion brings many primary aerosols and causes a large range of transboundary transport. On the other hand, the high concentration of aerosol causes a severe disturbance to the distribution of O₃. Traditionally, high-resolution assessments of the spatial distribution of aerosols and O₃ can be carried out using LiDAR technology. However, the negligence of the influence of aerosols in the process of O₃ retrieval in traditional differential absorption lidar (DIAL) leads to an error in the accuracy of ozone concentration. Especially when dust transit occurs, the errors become bigger. In this study, a self-customized four-wavelength differential-absorption LiDAR system was used to synchronously obtain the accurate vertical distributions of ozone and high-concentration aerosol. The wavelength index of concentrated aerosol was inverted and applied to the differential equation framework for O₃ calculation. This novel approach to retrieving the vertical profile of O₃ was proposed and verified by applying it to a dust pollution event that occurred from April to May 2021 in Anyang City Henan Province, which is located in Northern China. It was found that the extinction coefficient of aerosol reached 2.5 km⁻¹ during the dust period, and O₃ was mainly distributed between 500 m and 1500 m. The O₃ error exceeded over 10% arising from the high-concentration aerosol below 1.5 km during the dust storm event. By employing the inversion algorithm while considering the aerosol effects, the ozone concentration error was improved by over 10% compared with the error recorded without considering the aerosol influence especially in dust events. Through this study, it was found that the algorithm could effectively realize the synchronous and accurate inversion of high-concentration aerosols and O₃ and can provide key technical support for air pollution control in China in the future.

This study investigates a typical ozone pollution episode in Hong Kong from May 29 to 31, 2023. Based on the observations of a Differential Absorption Lidar (DIAL) system, both ozone and aerosols accumulated below 1.5 km during the pollution episode. Ozone exhibited distinct formation and accumulation characteristics, with concentrations exceeding 200 μg m⁻³. Aerosols presented evident features of regional transport and local coupling, with extinction coefficients surpassing 1.1 km⁻¹. During late spring to early summer, the northward extension of the Western Pacific Subtropical High (WPSH) established favorable conditions for ozone production. This background was amplified by Typhoon Mawar, whose peripheral circulation channeled pollutants from the Pearl River Delta into Hong Kong through horizontal and vertical pathways, significantly worsening near-surface air quality. The episode was eventually mitigated, as enhanced vertical mixing facilitated the dispersion and removal of accumulated pollutants. These results highlight the critical role of meteorological–chemical interactions in shaping this ozone pollution episode.

Quantifying the regional source of long-lived ozone precursors (especially GHGs) transported to Hong Kong is hampered by sparse observational data and computational limitations. This study introduces an observation-driven analytical framework that integrates a tracer ratio (ethylbenzene/m,p-xylene), wind–source–distance correlations to constrain transport corridors, and inventory mapping to determine the province- and sector-specific contributions, operationalized by identifying transport periods from observations, classifying sources with diagnostic ratios into five emission categories, deriving seasonal weighting factors via frequency normalization, mapping high-resolution inventory classes to these categories to restructure sectoral inventories, and combining normalized provincial spatial weights with the restructured inventories to quantify cross-boundary CO₂ and CH₄ emissions by sector and region. High-resolution measurements were conducted at the Cape D’Aguilar Supersite (CDSS), which showed dominant wintertime regional transport with mean concentrations of 435.29 ± 7.64 ppm (CO₂) and 2083.45 ± 56.50 ppb (CH₄). Thirteen transport periods were quantitatively analyzed, and province–sector contributions were estimated. The dominant provincial contributors were Guangdong (20.66%), followed by Jiangxi (18.36%) and Zhejiang (11.15%). Motor vehicles (70%), fuel combustion (15%), and solvent use (10%) were the primary contributing sectors. The framework enables province- and sector-specific attribution under stated assumptions and provides a tool for measuring cross-boundary mitigation and developing air quality and climate strategies in monsoon-affected coastal cities.

A shipborne campaign was conducted in China’s southeastern coastal waters (21° N–32° N) from 14 to 31 January 2024 to investigate atmospheric CO₂ and CH₄ concentrations and their offshore gradients. Advanced instrumentation enabled high-precision measurements, validated by canister sampling with strong correlations to reference data. The voyage employed a dual-route design: a northbound baseline along the mainland coast and a southbound route with offshore excursions up to 80 nm, facilitating the first quantification of GHG gradients in the continental shelf region. Baseline concentrations from the northbound route revealed regional variability: CO₂ levels ranged from 422.75 ± 9.96 ppm (Fujian) to 445.62 ± 1.51 ppm (Zhejiang), while CH₄ levels spanned 2005.78 ± 5.89 ppb (Fujian) to 2064.59 ± 13.93 ppb (Zhejiang). Southbound analysis at 10 nm intervals showed CO₂ gradients transitioning from positive to negative at ~30 nm and back to positive at ~70 nm, whereas CH₄ exhibited complex behavior, including a positive–negative–positive transition at 30–40 nm and consistent increase beyond 50 nm. Under winter monsoon conditions, transport flux analysis identified eastward CO₂ fluxes of 3819.55–6587.77 g·m⁻²·s⁻¹ and CH₄ fluxes of 6.42–11.42 g·m⁻²·s⁻¹. Southward transport diminished along the coast, with CO₂ fluxes declining from 5741.07 to 879.76 g·m⁻²·s⁻¹ and CH₄ fluxes from 9.84 to 1.49 g·m⁻²·s⁻¹ between Zhoushan and Hong Kong. The Taiwan Strait demonstrated a funneling effect, enhancing southward transport. These findings address data gaps in ocean regions and provide insights for future GHG monitoring.