This latest record low occurred just five years after the preceding record low in summer 2017, which is surprising and has raised concern about climate change in the Antarctic. In a paper recently published in Atmospheric and Oceanic Science Letters, Prof. LI Shuanglin from the Institute of Atmospheric Physics, Chinese Academy of Sciences and Dr. ZHANG Chao from the China University of Geosciences in Wuhan, attempt to uncover the underlying mechanisms of this record-low sea ice area.

 

 

"We found that the combination of stronger positive sea surface temperature anomalies in the Maritime Continent during July–September 2021 and the preceding near-strongest positive-phase Southern Annular Mode during August–October 2021 induced a deepened and southwestward-shifted Amundsen Sea Low, causing sea ice retreat via horizontal wind anomalies," explains Prof. LI.

 

The former persisted into summer and favored the development of La Ni？a, which triggered an atmospheric wave train emanating from eastern Australia and propagating southeastward, deepening the Amundsen Sea Low remotely. The latter remained strongest or close to strongest due to the stratospheric cooling effect of unprecedented ozone reduction, which induced a deepened and southwestward-shifted Amundsen Sea Low. 

 

"The unprecedented ozone reduction also played a role through the induced surface warming in the West Antarctic by increasing downward shortwave radiation. Additionally, positive feedback between sea surface temperatures, net shortwave radiation, and cloudiness, along with the Ekman heat transport, amplified the surfacing warming," adds Prof. LI.

 

 

 

Citation:

Chao Zhang, Shuanglin Li, 2023. Causes of the record-low Antarctic sea-ice in austral summer 2022. Atmospheric and Oceanic Science Letters, https://doi.org/10.1016/j.aosl.2023.100353.