The Physics of Summertime Antarctic Extreme Heat Events
Zachary Espinosa, University of Washington
Across much of the globe, extreme heat events have become more frequent and intense, amplifying the risk of their associated socio-economic damages. Antarctic heat waves in particular remain poorly understood, despite their impact on surface ice melt, sea level rise, and coastal ecosystems. Using daily historical near-surface air temperatures from 17 stations on the Antarctic continent, ECMWF reanalysis, and historical output from a CMIP-class GCM, we present a novel investigation into the evolution and drivers of summertime Antarctic extreme heat events. We find that recent trends in the Amundsen Sea Low and Southern Annual Mode have increased the frequency and intensity of extreme heat events along the Antarctic Peninsula. We perform a surface energy budget, and find that high-elevation Antarctic heatwaves are characterized by extreme moisture flux convergence, longwave radiation forcing, total column warming, and enhanced cloud cover. In contrast, low-elevation, coastal Antarctic heatwaves, depending on local geography, are driven by either down-slope winds, large surface sensible heat fluxes, and surface amplified warming or high-pressure ridging, and warm air advection. Finally, using a storyline approach, we nudge atmospheric winds in the Community Earth System Model version 2.2 (CESM2.2) to demonstrate that the amplitude of equivalent Antarctic heat waves will increase by a larger magnitude than the local warming expected from anthropogenic forcing.
Authors: Zachary Espinosa1, Edward Blanchard-Wrigglesworth1, Aaron Donohoe2, Tyler Cox1, Cecilia Bitz1
1Department of Atmospheric Sciences, University of Washington, USA
2Applied Physics Lab, University of Washington, USA
Abstract Author(s): (see above entries)