To evaluate the influence of urban non-uniformity on precipitation, the area of a city was divided into three categories （commercial, high-density residential, and low-density residential） according to the building ...To evaluate the influence of urban non-uniformity on precipitation, the area of a city was divided into three categories （commercial, high-density residential, and low-density residential） according to the building density data from Landsat satel- lites. Numerical simulations of three corresponding scenarios （urban non-uniformity, urban uniformity, and non-urban） were performed in Nanjing using the WRF model. The results demonstrate that the existence of the city results in more precip- itation, and that urban heterogeneity enhances this phenomenon. For the urban non-uniformity, uniformity, and non-urban experiments, the mean cumulative summer precipitation was 423.09 mm, 407.40 mm, and 389.67 mm, respectively. Urban non-uniformity has a significant effect on the amount of heavy rainfall in summer. The cumulative precipitation from heavy rain in the summer for the three numerical experiments was 278.2 mm, 250.6 mm, and 236.5 mm, respectively. In the non- uniformity experiments, the amount of precipitation between 1500 and 2200 （LST） increased significantly. Furthermore, the adoption of urban non-uniformity into the WRF model could improve the numerical simulation of summer rain and its daily variation.展开更多
This short paper presents an investigation on how human activities may or may not affect precipitation based on numerical simulations of precipitation in a benchmark case with modified lower boundary conditions, repre...This short paper presents an investigation on how human activities may or may not affect precipitation based on numerical simulations of precipitation in a benchmark case with modified lower boundary conditions, representing different stages of urban development in the model. The results indicate that certain degrees of urbanization affect the likelihood of heavy precipitation significantly, while less urbanized or smaller cities are much less prone to these effects. Such a result can be explained based on our previous work where the sensitivity of precipitation statistics to surface anthropogenic heat sources lies in the generation of buoyancy and turbulence in the planetary boundary layer and dissipation through triggering of convection. Thus only mega cities of sufficient size, and hence human-activity-related anthropogenic heat emission, can expect to experience such effects. In other words, as cities grow, their effects upon precipitation appear to grow as well.展开更多
基金supported by the National Basic Research Program of China(Program 973)(Grant Nos.2010CB428501 and 2014CB441203)the National Natural Science Foundation of China(Grant No.41575141)
文摘To evaluate the influence of urban non-uniformity on precipitation, the area of a city was divided into three categories （commercial, high-density residential, and low-density residential） according to the building density data from Landsat satel- lites. Numerical simulations of three corresponding scenarios （urban non-uniformity, urban uniformity, and non-urban） were performed in Nanjing using the WRF model. The results demonstrate that the existence of the city results in more precip- itation, and that urban heterogeneity enhances this phenomenon. For the urban non-uniformity, uniformity, and non-urban experiments, the mean cumulative summer precipitation was 423.09 mm, 407.40 mm, and 389.67 mm, respectively. Urban non-uniformity has a significant effect on the amount of heavy rainfall in summer. The cumulative precipitation from heavy rain in the summer for the three numerical experiments was 278.2 mm, 250.6 mm, and 236.5 mm, respectively. In the non- uniformity experiments, the amount of precipitation between 1500 and 2200 （LST） increased significantly. Furthermore, the adoption of urban non-uniformity into the WRF model could improve the numerical simulation of summer rain and its daily variation.
基金the support of the Hong Kong Research Grant Councils Early Career Scheme(No.104712)the support of the City University Institutional Post Graduate Studentship
文摘This short paper presents an investigation on how human activities may or may not affect precipitation based on numerical simulations of precipitation in a benchmark case with modified lower boundary conditions, representing different stages of urban development in the model. The results indicate that certain degrees of urbanization affect the likelihood of heavy precipitation significantly, while less urbanized or smaller cities are much less prone to these effects. Such a result can be explained based on our previous work where the sensitivity of precipitation statistics to surface anthropogenic heat sources lies in the generation of buoyancy and turbulence in the planetary boundary layer and dissipation through triggering of convection. Thus only mega cities of sufficient size, and hence human-activity-related anthropogenic heat emission, can expect to experience such effects. In other words, as cities grow, their effects upon precipitation appear to grow as well.
