A multi-method Antarctic atmospheric blocking dataset based on ERA5 (1979–2024)

Version 2.0, July 2026. This release supersedes Version 1 and updates the percentile-based blocking methodology. For each calendar day, the local 90th-percentile threshold is calculated from anomalies within a centred 15-day running window (±7 days), pooled across all reference years. This approach provides a sufficiently large sample for stable percentile estimates while preserving the gradual seasonal evolution of anomaly variability.This update affects the percentile-based methods (PV-Perc, Z500-Perc, and Z500-Perc_detrend) and may therefore modify their blocking masks and derived products relative to Version 1. Code availability: The archive atmospheric_blocking_ERA5_code_v1.0.0.zip contains the scripts used to generate Version 2.0 of this dataset. The workflows are designed for Linux and HPC environments and use ERA5 input data, Python, CDO, and TempestExtremes. Software requirements, workflow structure, and configuration instructions are provided in the included README. Code author: Charlie Opazo. Overview of the Blocking Dataset Each folder corresponds to one blocking detection method applied to either Z500 or PV. The dataset contains the following method folders: PV-Abs, PV-SD, PV-Perc, Z500-Abs, Z500-Abs_detrend, Z500-Grad, Z500-Perc, Z500-Perc_detrend, Z500-SD, Z500-SD_detrend. All methods use the same data structure described below. 1. Variables Z500Geopotential height at 500 hPa. PVVertically integrated potential vorticity (150–500 hPa). 2. Blocking Detection Methods (names only) Absolute threshold method: Z500-Abs, PV-AbsStandard deviation anomaly method: Z500-SD, PV-SDPercentile-based anomaly method: Z500-Perc, PV-PercGradient method: Z500-GradDetrended variants: Z500-Abs_detrend, Z500-Perc_detrend, Z500-SD_detrend 3. Contents of Each Method Folder Every method folder contains four subdirectories: 3.1 blocking/ Instantaneous blocking masks (6-hourly, 1979–2024).Each file contains gridcell values: 1 = blocked, 0 = not blocked. 3.2 blocking_id/ Event ID fields for tracked blocking events and each blocked gridcell has an event number. 3.3 clim/ Blocking climatologies derived from the full record.Provided at annual, seasonal, and monthly timescales.Each includes: Blocking frequency Blocking intensity Blocking persistence Example filenames:ERA5_blocking_frequency_PV-Perc_clim_annual_SH.ncERA5_blocking_intensity_PV-Perc_clim_seasonal_SH.ncERA5_blocking_persistence_PV-Perc_clim_monthly_SH.nc 3.4 time_series/ Time series of blocking metrics aggregated over the Southern Hemisphere.Provided at annual, seasonal, and monthly timescales.Each includes: Blocking frequency Blocking intensity Blocking persistence Example filenames:ERA5_blocking_frequency_PV-Perc_timeseries_annual_SH.ncERA5_blocking_persistence_PV-Perc_timeseries_seasonal_SH.ncERA5_blocking_intensity_PV-Perc_timeseries_monthly_SH.nc 4. Summary Each blocking method folder includes: 1. blocking/ — instantaneous masks 2. blocking_id/ — labeled events 3. clim/ — climatologies 4. time_series/ — time series