Drivers of extreme high temperature events over Antarctica

Climatic conditions of Antarctica range from the relatively warm maritime northern section of the Antarctic Peninsula to the frigid high plateau of East Antarctica. Antarctica contains 90% of the Earth’s ice. Antarctic ice melt has the potential to make a significant contribution to global sea-level rise (Noble et al. 2020). Although most melt so far has occurred when warm ocean waters flow under the peripheral ice shelves, high air temperatures have led to significant ice melt on the eastern side of the Antarctic Peninsula. With climate models suggesting that regional air temperatures will rise over the coming decades, a high priority in polar research is to understand the conditions that lead to the extreme temperature events and subsequent surface melt. A better understanding of the process would help us to derive more accurate projections of their future occurrence.

High temperature events can have a major impact of the Antarctic environment. Warm intrusions into the coastal region can result in surface temperature anomalies of +4-5º C on average. The synoptic situation at the time often consists of a warm ridge extending towards Antarctica in association with strong meridional flow. Large magnitude, more persistent events have been linked to atmospheric rivers, which are narrow bands of warm, moist air originating in lower latitudes (Wille et al., 2019). For instance, in March 2022, an atmospheric river that reached the high plateau of East Antarctica had resulted in 40º C surge of temperature with extensive surface melt. It is also puzzling that some of the high temperature events have been preceded by downslope flow from the interior of Antarctica, where the air is normally much colder than that on the coast (Turner et al. 2021). While many of these events are of short duration, they involve complex interactions between the air, ocean and ice. To date, the dynamical aspects of these temperature extreme events remain poorly understood. As we learn more about the associated circulation patterns, such as the February 2020 Peninsula record temperatures and the East Antarctic March 2022 “heatwave” and how those patterns interact with the ocean and sea ice, we will be able to improve climate models so that such events can be properly reproduced by model simulations. We then can use model predictions to assess the likelihood of such events becoming more common in the future.

This project will investigate high temperature events in the coastal Antarctica using a combination of station observations, assimilated data sets as well as regional climate simulations.