Search

Land surface parameters play a crucial role in simulations of weather and air quality. This study investigated the impact of underlying surface parameters on meteorological fields and pollutant concentrations in the Greater Bay Area (GBA), China, during warm and cold season. Updated land surface parameters, namely land use type, leaf area index, vegetation fraction, albedo, and roughness length, were incorporated to improve simulations. The model showed 7%–14% improvements (in terms of the index of agreement) in wind speed simulations, whereas temperature and relative humidity were not sensitive to the adoption of updated parameters. Moreover, compared with the model with default parameters, the model with updated natural underlying surface parameters showed a 2–3 m/s reduction in cross-border wind speed during cold season in the GBA. The model also showed a 1–2 m/s increase in the wind speed in urban areas, owing to thermal contrast. During periods in which clean air came from the north, the reduced wind speed hindered ozone removal in the GBA. The use of updated underlying surface parameters enhanced the urban heat island effect by ∼2 K and increased the wind speed over urban areas by ∼2 m/s. The intensified urban heat island circulation generated strong updrafts and intensified sea breezes, promoting the penetration of sea breezes inland. Additionally, the intensified sea breeze and urban heat island circulation contributed to a ∼10-ppb reduction in ozone concentrations. Hence, incorporating the latest land surface parameters improved the simulation of meteorological fields and influenced cross-border pollutant transportation. This study highlights the importance of considering underlying surface characteristics in regional modelling and provides insights for air pollutant management. • Latest land surface parameters are incorporated into WRF-CAMx for model improvement. • These updated inputs provide improved meteorological simulation, especially on wind speed. • The local circulations and intense updraft induced by UHI modulate the transportation of O 3. [ABSTRACT FROM AUTHOR]

In late September 2019, the longest and most extensive ozone (O 3 ) pollution process occurred at Pearl River Delta. Base on the observational data, surface-level O 3 , vertical distribution characteristics boundary layer O 3 as well as its effect on surface-level O 3 are thoroughly analyzed. The O 3 lidar results showed similar vertical O 3 profiles both in pollution episodes and clean periods, from which a high O 3 concentration layer between 300 and 500 m and a sub-high O 3 concentration layer between 1300 and 1700 m (near the top of the mixing layer) can be found. Besides, the downward O 3 transport paths from the high/sub-high O 3 concentration layers could be observed along with the boundary layer evolution: At nighttime, large amounts of O 3 were effectively stored into the residual layer (RL). Due to the upward development of Mixing layer (ML) in early morning, atmospheric vertical mixing carried the O 3 inside the RL down to the surface, which led to a rapid increase in the surface-level O 3 . The sub-high O 3 layer began the downward mixing at noon, and became well-mixed after the boundary layer was fully developed in the afternoon, by which the near surface O 3 pollution deteriorated again. Further analysis of the heavy O 3 pollution episodes show that, the high O 3 concentration inside the RL contributed 54% ± 6% of the surface-level O 3 at 9:00 LT and the average contribution of O 3 in the sub-high concentration layer to the surface-level O 3 at 14:00 LT was 26% ± 9%. Based on the quantitative analysis of the observational data, this paper focus to reveal the importance of the contribution of O 3 inside the RL and near the top of the ML to the surface O 3 ., Competing Interests: 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., (Copyright © 2021 Elsevier B.V. All rights reserved.)