Summary/Abstract
In boreal summer of 2022, Pakistan experienced extremely high rainfall, resulting in severe flooding and displacing over 30 million people. At the same time, heatwaves persisted over central China and Europe. The coexistence of these extreme events suggests a possible linkage. This study analyzes the confluence of these extreme events, and concludes that the record rainfall was mainly induced by compounding factors. These included (1) La Niña-induced strong anomalous easterlies over the northern Indian subcontinent, (2) intense southerlies from the Arabian Sea with an upward trend in recent decades, (3) an interaction between extratropical and tropical systems, specifically the northerly flow downstream of the Europe blocking and the southerly monsoon flow from the Arabian Sea. Wave activity flux and regression analyses unveiled a distinct stationary Rossby wave-like pattern connecting the flooding in Pakistan and heatwaves in Europe and China. This pattern, an emerging teleconnection pattern in recent decade, exhibited substantial differences from the reported teleconnection patterns. The study also notes that the positive feedback of the excessive Pakistan rainfall could further enhance the large-scale background flow and the heavy rainfall itself. The 2022 Pakistan flood event was an intensified manifestation of the 2010 Pakistan flood event, which was also caused by compounding factors, but occurred in a more pronounced upward trend in the both tropics and extratropics.