On the drivers of temperature extremes on the Antarctic Peninsula during austral summer

This study investigates the role of atmospheric circulation on intraseasonal and synoptic time scales in driving the temperature extremes over the Antarctic Peninsula (AP) during austral summer. It is found that the advection term induced by intraseasonal oscillations (ISOs) makes the largest contribution to the formation and development of temperature extremes. The synoptic variation-induced advection term affects the temperature anomalies around the peak time. The upstream ISO Rossby wave packet propagating along the jet stream south of Australia precedes the extreme temperature events. The ISO wave packet propagates eastward and eventually affects downstream circulation and relevant temperature anomalies over the AP. The perturbations triggered by the ISO wave packet can also gain energy from the mean flow through the potential energy conversion, contributing to the development and maintenance of ISO Rossby wave. The eastward propagation of the synoptic-scale Rossby wave is faster than that of the intraseasonal one. As such, the anomalous synoptic circulations rapidly change and facilitate the development of extreme temperature events. The synoptic Rossby wave activity before the warm events is much stronger than that before cold, which can be partly attributed to the background of more active baroclinicity before the warm events.