Impacts of urban expansion and future green planting on summer precipitation in the Beijing metropolitan area

Abstract

[1] In this study, an analysis of long-term rainfall data reveals that the rapid urban expansion in Beijing since 1981 is statistically correlated to summer rainfall reduction in the northeast areas of Beijing from 1981 to 2005. This coincides with the period in which the shortage of water in the Beijing area has become a serious factor for sustainable economic development. Meanwhile, an analysis of the aerosol optical depth (AOD) from the Total Ozone Mapping Spectrometer spanning the years from 1980 to 2001 shows that there is no clear secular trend in summer AOD in Beijing. With the particular purpose of further understanding the effects of urban expansion on summer rainfall and the potential measures to mitigate such effects, a mesoscale weather/land-surface/urbancoupled model along with different urban land-use change scenarios are used to conduct numerical simulations for two selected heavy summer rainfall events with different, but representative, summer weather patterns in Beijing. Results show that urban expansion can produce less evaporation, higher surface temperatures, larger sensible heat fluxes, and a deeper boundary layer. This leads to less water vapor, more mixing of water vapor in the boundary layer, and hence less (more) convective available potential energy (convective inhibition energy). The combination of these factors induced by expanding urban surfaces is helpful in reducing precipitation for the Beijing area in general and, in particular, for the Miyun reservoir area (the major source for the local water supply). Increasing green vegetation coverage in the Beijing area would produce more rainfall, and model results show that planting grass seems more effective than planting trees. For the same vegetation, the rainfall difference from simulations using two green-planting layouts (annular and cuneiform) is small.

Projection of precipitation extremes for eight global warming targets by 17 CMIP5 models

“…4.6. To a large extent, these uncertainties are related to complicated mechanisms responsible for the variation in extreme precipitation across China, including atmospheric circulation anomalies (Gong and Ho 2002;Wang and Li 2005;Ding et al 2008;You et al 2011), global warming Zhao et al 2010), urbanization (Zhang et al 2009;Miao et al 2011), aerosols (Zhao et al 2006), sea surface temperature (Gong and Ho 2002;Zhou et al 2008), land-use change (Gao et al 2003(Gao et al , 2007, geographical features such as the Tibetan Plateau ) at the regional scale, and so on. The atmospheric circulation is undoubtedly one of the most crucial causes of climate extremes.…”

Response of urban heat island to future urban expansion over the Beijing–Tianjin–Hebei metropolitan area

“…This meso-scale numerical modeling system is designed for atmospheric research and operational forecasting. Some large cities and urban agglomerations, such as Tokyo (Kusaka & Kimura, 2004), Taipei (Lin et al, 2008;Lin, Chen, Chang, & Sheng, 2010), Nanjing (Yang, Zhang, & Qian, 2012), and Beijing Zhang et al, 2009), as well as Yangtze River Delta (Zhang, Gao, Wang, & Chen, 2010), the BTH metropolitan area (Wang, Yan, Liu, & Zhang, 2013, and Pearl River Delta (Cheng & Chan, 2012;Wang, Wu, & Liang, 2009), have witnessed the simulation of the variation in UHI using this modeling system. The capability of the WRF modeling system has been highlighted to explore the impact of LULC change on UHI at the local or regional scales.…”

Urban impacts on air temperature and precipitation over The Netherlands

“…heat, water, and momentum be tween the land surface and overlying atmosphere), which cause alterations of the atmospheric composition and meteorology over urban areas (Peterson 2003, Kaufmann et al 2007, Pall et al 2007, Trusi lova et al 2008, Zhang et al 2009, Lin et al 2011, Stone et al 2012.…”