The impact of urbanization on air stagnation: Shenzhen as case study

One of the most concerning consequences arising from the dramatic urbanization in cities is air stagnation and the related high concentration of air pollutants. Many studies have investigated the impact of urbanization on air stagnation, but few have systematically evaluated such impact and its spatial-temporal variances at the municipal scale. This study proposed an approach based on high-resolution urban climate simulations for evaluating the impact of urbanization on air stagnation. We took the city of Shenzhen in south-eastern China, a city that grew from a small fishing and farming village to a highly urbanized city in the past thirty years, as a compelling case study. Using the WRF/Noah LSM/SLUCM model, we simulated and evaluated the probability of 6-hourly air stagnation cases (ASCs) in 1979 and 2010 at the spatial resolution of 1-km² to demonstrate the change over a thirty-year period. Comparison results show that urbanization worsened the problem of air stagnation in Shenzhen. The number of 6-hourly ASCs has increased by 21,700 for the entire Shenzhen, and by 11.4 on average for each grid with a 1 km² size. A maximum increase of 458 ASCs in a grid was also observed.