A Multi-Method Antarctic Atmospheric Blocking Dataset (1979–2024)

Abstract. Atmospheric blocking is a key driver of persistent circulation anomalies and associated extreme events in the Southern Hemisphere, yet its characteristics around Antarctica remain poorly understood due to methodological diversity and the absence of a consolidated, long-term dataset. This study presents a new multi-method Antarctic atmospheric blocking dataset covering the period 1979–2024, derived from ERA5 reanalysis and constructed using multiple blocking detection approaches applied consistently across the Southern Hemisphere (25° S–90° S). The dataset integrates diagnostics based on 500 hPa geopotential height and vertically integrated potential vorticity within a unified framework for spatial filtering, event definition, and temporal tracking. It provides instantaneous blocking masks, spatiotemporally tracked event catalogues, time series, and aggregated climatologies that are directly comparable across methods. The results reveal only weak large-scale similarities in Antarctic blocking across detection approaches, mainly related to high latitude occurrence and seasonal modulation. In contrast, pronounced method dependent diversity is evident in blocking frequency, spatial extent, the number of detected blocking events, and persistence. Geopotential height-based methods identify a broader spectrum of anticyclonic flow regimes, including events extending into the Antarctic interior, whereas potential vorticity-based methods isolate fewer, more spatially confined events that emphasize dynamically coherent upper-level disturbances near the polar vortex. Event-based diagnostics further reveal systematic trade-offs between event frequency and duration, illustrating how different methodological choices preferentially capture either shorter-lived circulation anomalies or more persistent blocking structures. These contrasts arise from the diverse dynamical expressions of blocking at high southern latitudes, indicating that no single diagnostic fully captures Antarctic blocking behavior. Key uncertainties relate to threshold sensitivity, spatial filtering, and diagnostic formulation, which should be considered when interpreting blocking statistics and inter-method differences. By providing a consistent and openly accessible resource, this dataset allows direct intercomparison of blocking definitions, supports evaluation of climate models over Antarctica, and provides a foundation for future studies of blocking-related circulation variability and extreme events.