The Increased Influence of Eastern European Blocking Highs on Extreme Rainfall Over Pakistan in Recent Decades

Abstract

Blocking highs over Eastern Europe (EEU) have been identified as significant drivers of the extreme precipitation events over Pakistan in 2010 and 2022. However, whether this insight is applicable over longer periods remains unclear. This study, on the basis of observations and reanalysis data from 1961 to 2022, statistical analysis and numerical simulations, reveals that the impact of EEU blocking high on precipitation in Pakistan has intensified after the 1990s and attributes this shift to the warming trend in the Arctic. In recent extreme rainfall cases, EEU blocking highs transmitted Rossby wave energy southeastward, crossing the polar front jet and subtropical jet and leading to a high‐pressure anomaly over China. This effect, coupled with the anomalous activities of tropical oceanic oscillations and the South Asian monsoon, created favourable conditions for extreme rainfall in Pakistan. Arctic warming contributed to this shift by altering the westerly jet over EEU. The jet changes displaced the blocking activity centre southward from the Barents and Kara Seas, facilitating the propagation of Rossby wave trains that connected the EEU blocking highs with extreme rainfall over Pakistan. This study elucidates the mechanisms driving extreme precipitation in Pakistan and offers valuable insights for future prediction. Given the continued warming trend, similar extreme rainfall events driven by these mechanisms are likely to recur in the future. This underscores the urgent need for local governments and international agencies to take more proactive measures to mitigate potential disasters.

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