Investigation of Causes and Characteristics of Monsoon Extremes in Pakistan: A Case Study for Summer Monsoon 2022

Abstract

Apart from the long-term changes in the normal weather patterns, the occurrence of short-lived extreme meteorological events has also emerged as a major consequential aspect of global climate change. Pakistan being listed among the most susceptible nations to the changing global climate patterns has witnessed an increasing frequency of extreme summer monsoon rainfall events during the past decades. This study was conducted to comprehensively investigate the major meteorological factors that lead to the extreme summer monsoon precipitation in Pakistan in 2022. The results obtained from the study showed that in April 2022, Balochistan observed 1.5 to 6 °C, Sindh observed 2 to 4 °C, while Punjab and KPK observed 3 to 5.5 °C above normal temperatures (1961-2010). In May, Sindh and Balochistan observed 1 to 3.5 °C above normal temperature, consequently causing intense low-pressure conditions over the area. In April 2022, about 1 to 2.5 mb below normal air pressure was found in Sindh and Balochistan, while in May, about 1 to 3 mb below normal pressure was found over the area. The summer monsoon 2022 analysis showed that in July, about 0.2 to 4 mb above normal vapor pressure was found in Sindh and Balochistan, while Punjab reported 1 to 5 mb above normal vapor pressure. In August, Balochistan and Sindh recorded 1 to 5 mb, while Punjab recorded 1.5 to 5 mb above normal vapor pressure. Further, the extreme monsoon precipitation was more concentrated in Sindh and Balochistan, as compared to the other provinces. In July 2022, Sindh received 307 %, Balochistan received 450 %, while Punjab received 116% above normal rainfall. In August, Sindh received the highest rainfall (+726% above normal) followed by Balochistan with the rainfall departure as +590%. Conclusively, it was established that the unusual pre-monsoon heating over the arid plains in Sindh, Balochistan and southern Punjab resulted in the development of intense trough over the area, that pulled excess moisture from the Indian ocean, causing high vapor pressures