时间：5月29日下午4:00

地点：1429会议室 

报告人：University of Arizona 谭先瑜博士

报告题目：Weather on extrasolar giant planets and brown dwarfs

报告摘要：Characterization of exoplanetary atmospheres reveals vigorous and exotic weather on these worlds, stimulating theoretical and numerical exploration on their atmospheric circulation. Two distinctive groups of exoplanets are particularly interesting. The first includes gaseous giant planets on close-in orbits around host stars, the so-called hot Jupiters, which are heavily irradiated and experienced permanent day-night forcing due to tidal locking. The second category includes giant planets that are far away from their host stars, the climates of which are primarily driven by the strong internal heat flux and shaped by fast rotation. Brown dwarfs are objects between stars and giant planets, sharing similar physical and chemical properties as young giant planets. In this talk we will briefly review current observational constraints of the climate and weather of these objects, then discuss our recent investigations on the atmospheric circulation of these two populations, focusing on understanding the basic dynamical processes and implications for observations. Specifically, for hot Jupiters, we will discuss the importance of dissociation of molecular hydrogen on shaping the circulation and global heat transport for those with atmospheric temperature exceeding ~ 2400 K. For distant giant planets and brown dwarfs, we introduce a novel circulation regime driven by radiative cloud feedbacks, and discuss the implications for observed variability and near-IR colour dispersion.