Advancing U.S. Operational
Amplification of Waveguide Teleconnections in the Boreal Summer
7 June, 2pm, in CPC Training room
Although it is still an ongoing controversy how climate change, especially Arctic warming, could have already impacted the midlatitude jet streams and Rossby wave variability, there is clear evidence that recent boreal summers have witnessed an increasing number of extreme events (heat waves, flash droughts, wild fires). Many of those events occurred at the same time as stagnant and high-amplitude circumglobal waves, which are associated with the waveguiding effect of the tropospheric mean jets. In this talk, I shall use a planetary wave model and the Community Earth System Model (CESM) to discuss what could be causing the amplification of the waveguide teleconnections in the boreal summer. The hypothesis that climate change can alter the basic circulation states and enhance circumglobal waveguide teleconnections through resonance has not yet been verified with models. On the other hand, recent general circulation model simulations, assisted by linear planetary wave models, indicate that enhanced terrestrial heating associated with the emerging midlatitude aridity can produce stronger midlatitude heating events during summer that stimulate the jet stream waveguides thus leading to more high-amplitude circumglobal planetary wave events.