【学术预告】广东省气候变化与自然灾害研究重点实验室和热带大气-海洋系统科学粤港澳联合实验室暨大气科学学院(2018年第31讲)

发布人:高级管理员 发布日期:2018-07-06 阅读次数:13

主讲人:Dr. Kalli Furtado

UK Met Office, Exeter, UK

题目:Convection permitting simulations of the climate of East Asia: diurnal cycle and extremes

 

时间:2018年7月6日(周五)上午10:00

地点:地环大楼C306室

主持人:陆希 讲师

 

本次学术报告将进行全程直播,
直播网址为:https://sysuatmos.webex.com.cn/
活动号:184 757 460,密码:888888

 

报告简介:

A limited area convection permitting model (CPM) based on the Met Office Unified Model, with a 0.04 degree (4.4 km) horizontal grid spacing, is used to simulate an entire warm-season of the East Asian monsoon (from April to September. The simulations are compared to rain gauge observations, reanalysis and to a lower resolution regional model with a 0.12 degree (13.2 km) grid spacing that has a parameterization of subgrid-scale convective clouds and precipitation. The 13.2 km simulation underestimates precipitation intensity, produces rainfall too frequently, and shows evident biases in reproducing the diurnal cycle of precipitation and low-level wind fields. In comparison, the CPM shows significant improvements in the spatial distribution of precipitation intensity, although it overestimates the intensity magnitude and has a wet bias over central eastern China. The diurnal cycle of precipitation over Mei-yu region, southern China and the eastern periphery of the Tibetan Plateau, as well as the diurnal cycle of low-level winds over both the Mei-yu region and southern China are better simulated by the CPM. Over the Mei-yu region, in both simulations and observations, the local atmospheric instability in the afternoon is favorable for upward motion and rainfall. The CPM receives more sensible heat flux from the surface, has a stronger upward motion, and overestimates water vapor convergence based on moisture budget diagnosis. All these processes help explain theexcessive late afternoon rainfall over the Mei-yu region in the CPM simulation.

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