Month: June 2025

Our new paper, “Compound heat and ozone pollution in the urban environment“, is published in Urban Climate (IF: 6.9).

The paper can be downloaded at https://doi.org/10.1016/j.uclim.2025.102511.

Authors: Chenghao Wang, Xiao-Ming Hu, Sarah Feron, Jessica Leffel, & Raúl R. Cordero

Abstract: Ground-level ozone pollution and extreme heat are closely linked environmental stressors that often peak during similar warm-season conditions. Their co-occurrence as compound events can significantly amplify negative health impacts, particularly in densely populated urban areas. In this study, we systematically characterized the frequency, duration, and cumulative intensity of warm-season compound heat and ozone pollution events across all urban areas and their rural surroundings in the contiguous U.S. (CONUS), using long-term, high-resolution daily air temperature and pollution datasets. We found that urban heat waves, defined using daily maximum air temperature, were generally more frequent, more intense, and longer lasting than their rural counterparts, primarily due to the daytime urban heat island effect. In contrast, over half of the U.S. cities experienced fewer, less intense, and shorter ozone pollution episodes than nearby rural areas, largely reflecting differences in ozone chemical regimes. Despite these contrasting patterns, compound heat and ozone pollution events were more frequent in 88.8 % of urban areas, with higher cumulative heat and ozone pollution intensities in 91.1 % and 88.1 % of cities, respectively. However, compound event durations tended to be shorter in urban environments. These findings highlight the dependence of such compound events on local factors such as precursor emissions, as well as background conditions such as regional meteorological patterns, emphasizing the need for tailored mitigation strategies to simultaneously reduce heat stress and ozone pollution. This study also lays the foundation for detailed regional numerical simulations to elucidate the mechanisms that drive urban–rural disparities during these compound events.

DOI: https://doi.org/10.1016/j.uclim.2025.102511

Our new paper, “Ultrafine-resolution urban climate modeling: Resolving processes across scales“, is published in Journal of Advances in Modeling Earth Systems (IF: 4.6).

The paper can be downloaded at https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2025MS005053.

Authors: Chenghao Wang, Yongling Zhao, Qi Li, Zhi-Hua Wang, & Jiwen Fan

Abstract: Recent advances in urban climate modeling resolution have improved the representation of complex urban environments, with large-eddy simulation (LES) as a key approach, capturing not only building effects but also urban vegetation and other critical urban processes. Coupling these ultrafine-resolution (hectometric and finer) approaches with larger-scale regional and global models provides a promising pathway for cross-scale urban climate simulations. However, several challenges remain, including the high computational cost that limits most urban LES applications to short-term, small-domain simulations, uncertainties in physical parameterizations, and gaps in representing additional urban processes. Addressing these limitations requires advances in computational techniques, numerical schemes, and the integration of diverse observational data. Machine learning presents new opportunities by emulating certain computationally expensive processes, enhancing data assimilation, and improving model accessibility for decision-making. Future ultrafine-resolution urban climate modeling should be more end-user oriented, ensuring that model advancements translate into effective strategies for heat mitigation, disaster risk reduction, and sustainable urban planning.

DOI: https://doi.org/10.1029/2025MS005053