报告题目：Amplification of the subtropical stationary waves and their implications on regional water extremes

报告人：Wenhong Li

报告时间：2019年07月08日上午10:00

报告地点：地理所A901会议室

报告人简介：

Wenhong Li，from Duke University, she is the Associate Professor of Climate and Associate Professor in the Department of Civil and Environmental Engineering. Dr. Li's research interests focus primarily on climate dynamics, land-atmosphere interaction, hydroclimatology, and climate modeling. Her current research is to understand how the hydrological cycle changes in the current and future climate and their impacts on the ecosystems, subtropical high variability and change, unforced global temperature variability, and climate and health issues.

摘要：The linkage between climate change and increased frequency/magnitude of weather extremes remains an open question in the scientific field. Here we investigate such a dynamical linkage by focusing on an amplification trend of the northern subtropical stationary waves found in recent decades and the response of such waves to increasing climate forcing using CMIP5 models. It is shown that in multiple modern reanalysis products, a robust positive trend exists in a wave amplitude index defined through the summer-mean tropospheric stream function field. Pronounced changes in the subtropical atmospheric circulation accompany this wave amplification, including an intensified South Asian monsoon and strengthened subtropical highs over the North Pacific and North Atlantic oceans. Through modifying the characteristics of large-scale moisture transport, these circulation changes are coupled to changes in the regional precipitation amount and the occurrence of water extremes including both droughts and heavy rainfall events. Given this connection, amplified stationary waves have likely contributed to the elevated occurrence probabilities of droughts in the central United States, Mexico, Japan, and northern China, as well as those of heavy rainfall events in South Asia, southeastern China, and the eastern United States. In the future as climate warming continues, the amplification of subtropical stationary waves will increase the risk of water extremes over the above-mentioned regions.

陆地水循环及地表过程院重点实验室