Numerical Studying of the Urban Scale and Layout Effect on Atmospheric Environment

Abstract

AbstractFor investigating the urbanization development effect on the local and surrounding atmospheric environment, some numerical experiments are employed by adopting the typical meteorological condition in this paper. The simulation region was chosen for the urban district and three important satellite town of Beijing, which are the main developing direction of Beijing planning in recent twenty years. The simulation results show that, firstly, the urban development has great effect on the local environment. On a clear, calm summer meteorological condition, as urban area fraction in simulation region increasing of 19%, the mean air temperature on urban region increase 1.91°C; and as the vegetation fraction reducing 20% the mean specific humidity decrease 3.3 g·kg–1. Furthermore, the different urban layout and scale lead to the different influence on meteorological environment. At the same time, the variety of local urban scale and layout influence the atmospheric environment of surrounding region greatly, and the urban area is larger, the influence is more marked. Such as, 1) reasoning for the existent of Beijing downtown area, the temperature increment of surrounding towns reach the maximum of 1.2°C at 14:00, the mixture layer depth rise about 150 m, and the turbulence kinetic energy increase about 0.15 m2·s–2; 2) The urban construction and development change the meteorological environment. At the same time, the air pollution transporting and dispersing have been altered. The existent of Beijing downtown area leads to the decrease of the total allowable emission about 18.02 t·d–1. Identically, the contribution ratio of the surrounding towns expanding to PM10 concentration of downtown area reaches about 0.192 t·d–1.