Impacts of urban heat island intensities on a bifurcating thunderstorm over Beijing

Publication Date

5-1-2024

Document Type

Article

Publication Title

Urban Climate

Volume

55

DOI

10.1016/j.uclim.2024.101955

Abstract

To gain the insight into the impacts of different urban thermal conditions on precipitation, a series of simulations that modified the surface sensible heat from building is performed during a thunderstorm passage over Beijing. The UHI intensity changed from 0.8 to 2.2 °C with the increase sensible heat. Results showed that: (i) Under weak UHI conditions (≤1.4 °C), it is the urban dynamical effect that played the dominant role. The surface flow was blocked by the urban rough surface, inducing updrafts around the central urban area (CUA) and downdraft over the CUA. As the thunderstorm passed, its convergence line broke over the CUA. The precipitation thus bifurcated; (ii) Under strong UHI conditions (≥1.8 °C), it is the urban thermal factor that played the dominant role, overshadowing the urban dynamical impacts which still existed. The intensified UHI led to a more organized UHI circulation, with stronger updrafts over the CUA. When the storm arrived, the pre-existing updraft and convergence was conducive to convection initiation and enhancement. The precipitation thus concentrated over CUA and strengthened. Employment of a cooling tower scheme improved the simulated precipitation. This study thus represents an initial attempt to differentiate urban thermal and dynamic impacts on thunderstorms.

Funding Number

42330608

Funding Sponsor

National Natural Science Foundation of China

Keywords

Precipitation, UHI, Urban dynamical conditions, Urban impacts, Urban thermal conditions

Department

Meteorology and Climate Science

Link to Full Text

Share

COinS