Title: Large-scale Variability of Atmospheric Rivers and Climate Feedback
Lecturer: Gang Chen, UCLA
Time: Friday September 8, 2023 at 2:00 PM
Venue: Lecture Hall D103, School of Atmospheric Sciences, Xianlin Campus
Abstract: Atmospheric rivers (ARs) describe intense poleward moisture transport in the atmosphere. ARs have received considerable attention in recent years due to their impacts on hydrological extremes over the North American west coast and western Europe. However, the physical processes that drive ARs’ large-scale variability and climate feedback are not yet well understood. In this talk, I will first show that the climate responses of ARs resemble the spatial patterns of the leading EOF modes of unforced AR variability, which are influenced by both atmospheric moisture and circulation variability. Using idealized and comprehensive climate models, I will further demonstrate that changes in AR statistics in a warming climate can be understood as passive water vapor and cloud tracers that are moistened in the lower troposphere and regulated by large-scale atmospheric circulation. Finally, the latent energy carried by ARs makes an important contribution to polar climate feedback. It is found that the AR occurrence is significantly correlated with negative sea ice area anomalies around the Barents-Kara Seas during the ice recovery season. Observations and model simulations suggest that more frequent ARs in the Arctic over the past four decades account for approximately 1/3 of the sea-ice cover decline in the Barents-Kara Seas and central Arctic. These findings highlight the role of ARs in climate variability and feedback.
Brief introduction to the speaker: Dr. Gang Chen is a professor in the department of Atmospheric and Oceanic Sciences at University of California, Los Angeles. He received his bachelor’s degree from Peking University in 2002 and Ph.D. degree from Princeton University in 2007. Prior to UCLA, he worked as postdoctoral fellow at MIT and held faculty position at Cornell University. His research area is atmospheric and climate dynamics, focusing on atmospheric circulation and chemical transport in a changing climate.