Valley city ventilation under the calm and stable weather conditions: A review

Abstract

For valley cities, the high frequency calm and stable weather conditions caused by terrain barrier and temperature inversion will result in very unfavorable diffusion conditions and limited environmental capacity, leading to frequent haze and heat waves. In this case, the interaction of two mesoscale circulations, slope flow and urban heat island circulation, is the basic model of valley urban ventilation, which dominates the dissipation of heat and pollutants in urban areas. At present, some studies have been conducted to understand the above process. In this paper, a critical review of relevant studies has been made from the perspectives of research methods and research contents, respectively. Meanwhile, shortcomings of existing researches will be discussed in order to explore new research directions in the field of valley city ventilation.