The interaction of an urban heat island with a sea breeze front during moist convection over Tianjin, China

This study analysed a moist convection process which took place during the daytime on 22 July 2018 over Tianjin (China), which was caused by an interaction between anurban heat island (UHI) and the sea breeze front (SBF). The Weather Research and Forecasting (WRF) model was used for simulation and two sensitivity experiments (SEs) were designed to investigate the different effects of the UHI and the SBF. The results showed that the simulation results can represent the convection well. During the event, the easterly wind behind the SBF transported a cool, moist air mass from the sea (which provided the moisture supply) over the dry, warm urban centre, which provided triggering mechanism for the moist convection. The UHI was enhanced at the beginning of the process, providing turbulence mixing through the sensible heat flux from the urban surface but weakened after the precipitation occurred. The UHI and urban surface obstructed the westward movement of the SBF and maintained it near the urban centre, providing moisture and energy for the moist convection.