讲座题目：Simulating the urbanization impacts on extreme precipitation in thePearl River Delta megacity
主讲人：谭志勇 副教授，香港中文大学
主持人：刘敏 教授
开始时间：2017-08-30 15:00:00
讲座地址：闵行地理科学学院资环楼354报告厅
主办单位：地理科学学院，地理信息科学教育部重点实验室
报告人简介：
谭志勇，香港中文大学本科（1993）、硕士（1996）、美国普林斯顿大学博士（2004）。先后在美国夏威夷大学太平洋国际研究中心（2004-2006）、韩国釜山APEC气候中心（2006-2008）进行博士后研究，香港城市大学讲师、副教授（2008-2014）；现担任香港中文大学副教授（2014年至今）。谭志勇副教授主要通过数值模拟来研究“大气-海洋”互动过程，以及全球气候变异过程等问题；尤其在全球变暖ENSO事件、亚洲季风变化、大尺度城市化气候效应等方面做了较为出色的工作，先后多次获得香港研究基金会（Research Grant Council）项目支持；在GRL、JC、JGR、Monthly Weather Review等地学核心刊物发表SCI论文数十篇，SCI论文总引近千次，h指数15（Google Scholar）。
报告摘要：
In this first part of this talk we examine the sensitivity of local precipitation statistics to surface heat fluxes in an urban subdomain in the Pearl River Delta region, which is situated along the coast of south China. By conducting simulations of a past record-breaking rainfall event with a cloud-resolving model, we found that rainfall rates and the spatial distribution of accumulated rainfall are very sensitive to imposed urban surface heat fluxes. Diagnostics of the planetary boundary layer show increasing fluctuations of turbulence and buoyant turbulence production with increasing surface heat emission, causing increased near-surface mixing and convection. Heavy precipitation rates show a higher sensitivity than lighter rates. The extreme tail of the distribution is hence more affected. In the second part, we investigate how the size of a city might affect the local heavy precipitation statistics, using the same mesoscale atmospheric model. Our result shows that only mega cities of sufficient size, and hence human-activity-related anthropogenic heat emission, can expect to have significant enhancement of the likelihood of extreme precipitation. In other words, as cities grow, their effects upon precipitation appear to grow as well.