第一届未来大气科学论坛

In this paper, numerical experiments by establishing the urban aerosol cloud microphysical scheme to study the effect of urbanization-induced land use and aerosol on two types of summer strong precipitation: the westerly trough (WT) and the interaction between subtropical high and western trough (SH). For WT, it is characterized by a low water vapor flux (4.3 g s^-1 hPa^-1 cm^-1) at 850 hPa, a strong urban heat island intensity (1.4 ℃), and unfavorable aerosol diffusion. The strong urban heat island intensity increases convection by enhancing convergence at the low level, thereby resulting in approximately a 15% increase in precipitation in urban areas. Furthermore, urbanization-induce aerosol is activated to form more cloud droplets, further enhancing convection and precipitation (24%) by increasing latent heat release. As for SH, it is characterized by a high water vapor flux (9.5 g s^-1 hPa^-1 cm^-1) at 850 hPa, which eliminates the urban heat island effect. The diffusion of aerosols to the southwest form a large number of cloud droplets, which increase the precipitation in the area by about 22% mainly through the warm cloud process. However, the weakening of wind speed in urban areas, in addition no urban heat island has been formed, which together to inhibit the development of convection, thereby reducing precipitation in urban areas.
 

城市气象