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<p>Bangladesh experienced its most intense, widespread, and prolonged heatwave on record during April-May 2024, causing severe socioeconomic disruptions. This study investigates the event’s evolution, characteristics, and physical drivers, outlining its onset, peak, and decay phases. The heatwave was record-breaking (1940–2024), lasted 30 consecutive days, peaked at + 4.2&#xa0;°C above normal, and affected ~ 90% of the country, coinciding with severe drought-like conditions. It was dynamically triggered by high sea level pressure, and thermodynamically intensified by strong soil moisture (SM) – temperature (Tmax) coupling, ending with increased precipitation. Interestingly, SM reached a ‘critical dryness threshold’ at -0.138 m<sup>3</sup>/m<sup>3</sup> during the peak phase, distinguishing a coupled regime (SM&gt;-0.138 m<sup>3</sup>/m<sup>3</sup>) and a decoupled (SM≤-0.138 m<sup>3</sup>/m<sup>3</sup>) regime. In the coupled regime, Tmax anomalies peaked at + 4.5&#xa0;°C due to strong SM-Tmax feedbacks, while in the decoupled regime, reduced cloud cover enhanced solar radiation, raising Tmax to + 3°C. The Indian Ocean Dipole (IOD) is likely linked to heatwave drivers, potentially acting as a precursor by inducing atmospheric subsidence, pressure anomalies, and suppressed rainfall. ERA5 underestimates Tmax, suggesting the actual events were likely more intense. The magnitude of the underlying drivers made the 2024 event unprecedented compared to historical events. However, results highlight the pivotal role of land-atmosphere coupling as well as oceanic influence in climatic extremes, and improve understanding and prediction of extreme heatwaves in Bangladesh.</p>

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Drivers of the April–May 2024 record-breaking heatwave in Bangladesh

  • 期刊论文

  • 发表日期：

    2026年3月11日

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  • Sanjit Kumar Mondal,
  • Hui Tao,
  • Md Afjal Hossain,
  • Tong Jiang,
  • Soon-Il An,
  • Seung-Ki Min,
  • Zbigniew W. Kundzewicz,
  • Zehua Fang

摘要

Bangladesh experienced its most intense, widespread, and prolonged heatwave on record during April-May 2024, causing severe socioeconomic disruptions. This study investigates the event’s evolution, characteristics, and physical drivers, outlining its onset, peak, and decay phases. The heatwave was record-breaking (1940–2024), lasted 30 consecutive days, peaked at + 4.2 °C above normal, and affected ~ 90% of the country, coinciding with severe drought-like conditions. It was dynamically triggered by high sea level pressure, and thermodynamically intensified by strong soil moisture (SM) – temperature (Tmax) coupling, ending with increased precipitation. Interestingly, SM reached a ‘critical dryness threshold’ at -0.138 m3/m3 during the peak phase, distinguishing a coupled regime (SM>-0.138 m3/m3) and a decoupled (SM≤-0.138 m3/m3) regime. In the coupled regime, Tmax anomalies peaked at + 4.5 °C due to strong SM-Tmax feedbacks, while in the decoupled regime, reduced cloud cover enhanced solar radiation, raising Tmax to + 3°C. The Indian Ocean Dipole (IOD) is likely linked to heatwave drivers, potentially acting as a precursor by inducing atmospheric subsidence, pressure anomalies, and suppressed rainfall. ERA5 underestimates Tmax, suggesting the actual events were likely more intense. The magnitude of the underlying drivers made the 2024 event unprecedented compared to historical events. However, results highlight the pivotal role of land-atmosphere coupling as well as oceanic influence in climatic extremes, and improve understanding and prediction of extreme heatwaves in Bangladesh.