Evaluating Uncertainty and Modes of Variability for Antarctic Atmospheric Rivers

Antarctic atmospheric rivers (ARs) are driven by their synoptic environments and lead to profound and varying impacts along the coastlines and over the continent. The definition and detection of ARs over Antarctica accounts for large uncertainty in AR metrics, and consequently, impacts quantification. We find that Antarctic-specific detection tools consistently capture the AR footprint inland over ice sheets, whereas most global detection tools do not. Large-scale synoptic environments and associated ARs, however, are broadly consistent across detection tools. Using data from the Atmospheric River Tracking Method Intercomparison Project and global reanalyses, we quantify the uncertainty in Antarctic AR metrics and evaluate large-scale environments in the context of decadal and interannual modes of variability. The Antarctic western hemisphere has stronger connections to both decadal and interannual modes of variability compared to East Antarctica, and the Indian Ocean Dipole's influence on Antarctic ARs is stronger while in phase with El Nino Southern Oscillation.

Automated summary

Atmospheric rivers (ARs) in Antarctica are influenced by synoptic environments and have varying impacts along coastlines and the continent. Detecting and defining ARs in Antarctica is challenging, but specific tools are effective in capturing ARs over inland ice sheets. Although different detection tools may yield inconsistent results, the large-scale synoptic environments and associated ARs show broad consistency. The western hemisphere of Antarctica is more connected to decadal and interannual modes of variability compared to the eastern hemisphere, and the influence of the Indian Ocean Dipole on Antarctic ARs is stronger when in phase with El Nino Southern Oscillation.