Temperature extremes and atmospheric rivers in Antarctica

Atmospheric rivers (ARs) in Antarctica cause strong intrusions of moisture and heat, resulting in intense precipitation events and elevated temperature levels. Here, we examine observed trends in the occurrence of temperature extremes and temperature anomalies at 17 science stations between mid-20th century and 2022 and look at their potential links to ARs. Annual daily maxima of temperature and temperature anomaly are considered extreme if they exceed the 99.7th percentile of the distribution of the variable. Using statistical theory on extreme values, the trend in 10-year return levels of these variables is analyzed. The occurrence of ARs is in turn retrieved using detection algorithms based on meridional integrated vapor transport (vIVT) and integrated water vapor (IWV) calculations. The results show a significant increase (p < 0.1) in the 10-year return levels of extreme temperatures for three stations on the Antarctic Peninsula, one in the eastern Weddell Sea region and two on the East Antarctic shelf. At the same time, over the East Antarctic Ice Sheet, a significant (p < 0.1) decrease in decadal return levels is observed at four stations. The relationship between these extremes and atmospheric rivers depends on the detection scheme used, but the results indicate that 7-54% of temperature extremes are associated with ARs, while 19-75% of extreme anomalies are associated with ARs. A strong increase in the frequency of atmospheric rivers is observed in the Antarctic Peninsula, which could explain the increase in temperature extremes in this region.
The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)