Response of Persistent Wave Events to an Idealized Arctic Amplification Signature

With accelerated sea-ice melt in the Arctic, it is shown that the Arctic regions, under climate change, will heat quicker than the rest of the globe thus decreasing the equator-to-pole temperature gradient, known as Arctic Amplification (AA). Disagreements abound for how the midlatitude jet system may respond to an externally forced reduction in this temperature gradient. Specifically, changes in jet stream characteristics, wave amplitudes and phase speeds, and the link with extreme weather, such as heat waves, cold spells, atmospheric rivers and floods, and more, has received much attention from scientists, the media, and the general public. With the complexity of the climate system and highly coupled models, a hierarchical approach can separate the effects of the climate system and focus entirely on an idealized atmospheric response. By altering the surface equator-to-pole temperature difference in the GFDL dry dynamical atmospheric model, this study will focus on the response of persistent midlatitude wave patterns and extreme weather events. It has recently been shown that the finite amplitude local wave activity (LWA), identifies the latitude-longitude structure of large amplitude wave events, either cyclonic or anticyclonic, associated with extreme weather. By employing a tracking algorithm to characterize persistent, large amplitude wave events, the LWA is shown to capture robust features associated with classic atmospheric blocking, such as persistent Rossby wave breaking and persistent anomalies. It is shown that AA leads to a decelerated and equatorward shifted midlatitude jet and an increase in cyclonic and anticyclonic wave amplitudes resulting in an increase in the frequency of high latitude, persistent wave events. Contributing to this increased wave event frequency, there is an increase in the duration and amplitude of persistent wave events that could lead to an increase in extreme weather events for this idealized configuration.