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Prolonged effect of the stratospheric pathway in linking Barents–Kara—Sea sea ice variability to the midlatitude circulation in a simplified model
来源:LASG    访问次数:    报告时间:2017-8-11
【报告人】        Dr. Pengfei Zhang
【报告人单位】Purdue University, USA
【报告时间】    2017年8月11日(星期五)16:00
【报告地点】    科研楼303会议室
【报告简介】    To better understand the dynamical mechanism that accounts for the observed lead-lag correlation between the early winter Barents–Kara Sea (BKS) sea ice variability and the later winter midlatitude circulation response, a series of experiments are conducted using a simplified atmospheric general circulation model with a prescribed idealized near-surface heating over the BKS. A prolonged effect is found in the idealized experiments following the near-surface heating and can be explicitly attributed to the stratospheric pathway and the long time scale in the stratosphere. The analysis of the Eliassen-Palm flux shows that, as a result of the imposed heating and linear constructive interference, anomalous upward propagating planetary-scale waves are excited and weaken the stratospheric polar vortex. This stratospheric response persists for approximately 1–2 months accompanied by downward migration to the troposphere and the surface. This downward migration largely amplifies and extends the low-level jet deceleration in the midlatitudes and cold air advection over central Asia. The idealized model experiments also suggest that the BKS region is the most effective in affecting the mid-latitude circulation than other regions over the Arctic.
 
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