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Publication Date
23 November 2020

Urbanization-induced land and aerosol impacts on sea-breeze circulation and convective precipitation



Changes in land cover and aerosols resulting from urbanization may impact convective clouds and precipitation. Here we investigate how Houston urbanization can modify sea-breeze induced convective cloud and precipitation through urban land effect and anthropogenic aerosol effect. The simulations are carried out with the Chemistry version of the Weather Research and Forecasting model (WRF-Chem), which is coupled with the spectral-bin microphysics (SBM) and the multilayer urban model with a building energy model (BEM-BEP). We find that Houston urbanization (the joint effect of both urban land and anthropogenic aerosols) notably enhances storm intensity (by ~15 m s-1 in maximum vertical velocity) and precipitation intensity (up to 45%), with the anthropogenic aerosol effect more significant than the urban land effect. Urban land effect modifies convective evolution: speed up the transition from the warm cloud to mixed-phase cloud thus initiating surface rain earlier but slowing down the convective cell dissipation, all of which result from urban heating induced stronger sea breeze circulation. The anthropogenic aerosol effect becomes evident after the cloud evolves into the mixed-phase cloud, accelerating the development of storm from the mixed-phase cloud to deep cloud by ~ 40 min. Through aerosol-cloud interaction (ACI), aerosols boost convective intensity and precipitation mainly by activating numerous ultrafine particles at the mixed-phase and deep cloud stages. This work shows the importance of considering both urban land and anthropogenic aerosol effects for understanding urbanization effects on convective clouds and precipitation.
“Urbanization-Induced Land And Aerosol Impacts On Sea-Breeze Circulation And Convective Precipitation”. 2020. Atmospheric Chemistry And Physics 20: 14163-14182. doi:10.5194/acp-20-14163-2020.
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