Urban impacts on summertime rainfall in Beijing

1. Urban impacts on summertime rainfall in Beijing PEI Grand Challenges program and MIRTHE (Mid Infrared Technologies for Health and Environment) Summer 2008 Raleigh Martin ‘08

2. Understanding the effects of air pollution on Beijing’s climate Project components • Air-quality monitoring (QCLOPS and NO sensor) • Analysis of meteorological data • Review of existing studies • Atmospheric modeling using WRF

3. Study region • Monsoon climate: cold dry winters and hot moist summers. • Mean annual precipitation = 570 mm/yr • June-July-August precipitation = 420 mm/yr • Average 2.1 days per year with precipitation over 50 mm (Wang and Li, 2007)

4. Rapid urbanization and declining precipitation in Beijing 13.3 km2/yr increase in urbanized area 10.5 mm/yr decrease in summer precipitation 12.4 mm/yr decrease in summer precipitation near Miyun Reservoir (Zhang et al. 2007)

5. Literature Review • Most studies of Beijing’s climate are in Chinese!!! Main points from review: • Growing urban heat island since 1975 (Sun and Shu 2007) and effects of urban heat fluxes on storms (Zhang et al. 2007) • Importance of orography (Zhang et al. 2005) • Short thunderstorm life-cycle, low-level convergence and upper-level divergence, importance of wind shear (Fu and Guo 2007, Zheng and Zhang 2007, He et al. 2007)

6. WRF 2-domain: WRF modeling • Problems of model sensitivity to storms • Sensitivity analyses to better understand model function Mao et al. 2008: WRF 4-domain:

7. Thanks to the MIRTHE Beijing team!

8. References • Fu, D., Guo, X., 2007. Numerical Study on a Severe Downburst-Producing Thunderstorm on 23 August 2001 in Beijing (English). Advances in Atmospheric Sciences 22 (2). • He, L., Chen, T., Zhou, Q., Li, Z., 2007. The Meso-β Scale Convective System of a Heavy Rain Event on July 10, 2004 in Beijing (Chinese). Journal of Applied Meteorological Science 18 (5). • Mao, D., Qiao, L., Chen, T., Xu, H., Yang, K., 2008. Numerical Simulation and Analysis of a Local Storm in Beijing on 10 July 2004 (Chinese). Meteorological Monthly 34 (2). • Sun, J., Shu, W., 2007. The Effect of Urban Heat Island on Winter and Summer Precipitation in Beijing Region (Chinese). Chinese Journal of Atmospheric Sciences 31 (2). • Wang, S., Li, W. (Eds.), 2007. Climate of China. China Meteorological Press. • Zhang, C., Li, C., Kuo, Y.-H., Fan, S., Xuan, C., Chen, M., 2005. Numerical Simulation and Analysis of The Effect of Orography on the ﾒ00.7ﾓ Thunder- storm in Beijing (Chinese). Advances in Natural Sciences 15 (5). • Zhang, C., Miao, S., Li, Q., Chen, F., 2007. Impacts of fine-resolution land use information of Beijing on a summer severe rainfall simulation (Chinese). Chinese Journal of Geophysics 50 (5). • Zhang, C., Chen, F., Mia, S., Li, Q., Xuan, C., 2007. Influences of urbanization on precipitation and water resources in the metropolitan Beijing area. The 87th AMS Annual Meeting (San Antonio, TX). • Zheng, Z., Zhang, X., 2007. Numerical Study on Relationship between Low Level Jet and Local Heavy Rain in Beijing (Chinese). Journal of Nanjing Institute of Meteorology 30 (4).