A climatology of wave-breaking events with blocking flow configurations in the extratropical Southern Hemisphere

Based on three daily reanalysis datasets for the period from 1958 to 2023, this study details the climatology of high-amplitude wave breaking (WB) events with blocking flow configurations over the extratropical Southern Hemisphere (SH). A given event is classified as a WB blocking high (WBBH) or blocking low (WBBL) event, depending on the polarity of the primary height anomaly center. Furthermore, these events are classified as an eastwards (E) type or westwards (W) type according to the longitudinal movement of the primary potential vorticity center. Both WBBH and WBBL occurrences are predominantly E-types. Specifically, E-type WBBH events are more frequent over the South Pacific and adjacent regions, such as the southeast Indian Ocean and southwest Atlantic. In contrast, E-type WBBL events tend to occur over the 45°S-60°S latitudinal band. On the other hand, W-type events are more likely to occur over the Antarctic continent. The distribution frequency of WB events is closely associated with the climatological mean flow, but no evident seasonal preference for their occurrence regions is observed. The composite results at several representative locations demonstrate a robust relationship between the anomalous potential vorticity flux at the primary potential vorticity center and the convergence/divergence of the wave-activity flux, reinforcing the understanding of the dynamics underlying these events.