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<p>Climate hazards driven by extreme events have recently gained attention due to their severe environmental and socio-economic impacts. While independent daytime and nighttime heatwaves have been widely studied, compound heatwaves (CHWs) remain poorly documented in Africa. This study provides the first comprehensive assessment of summer CHWs in North Africa, identifying the corresponding dominant atmospheric and surface drivers using reanalysis data and CORDEX-CORE regional climate simulations for the period 1979–2023. Compound heatwaves show strong spatial variability across North Africa, occurring more frequently along the populated coastal regions and less often over mountainous areas such as the Atlas. These events are associated with pronounced temperature anomalies; they tend to develop under a persistent dipole configuration at 500&#xa0;hPa, characterized by a ridge located either over the western part of the region (Morocco) or over the eastern sector (Egypt). This circulation pattern favors subsidence and adiabatic warming, while warm air advection from the central Sahara further increases near-surface temperatures. Enhanced downward longwave radiation emerges as the dominant radiative contribution to surface warming, whereas solar radiation plays a comparatively secondary role. The assessment of regional climate models’ capabilities shows systematic biases in the representation of these events, generally underestimating their occurrence in coastal and Mediterranean regions while overestimating them over the central Sahara. Our analysis further indicates that the representation of compound heatwaves is more strongly influenced by the regional climate model configuration than by the driving global model. These findings help advance the understanding of compound heatwave dynamics in North Africa and showcase the need to improve their representation in regional climate models. By characterizing the mechanisms related to these events, this study helps support climate risk assessment and adaptation, particularly in light of the increasing impacts of heat extremes on public health, water resources, agriculture, and energy systems across the region.</p> Graphical Abstract <p></p> <p><?tk 2?>This study provides the first comprehensive characterization of summer compound heatwaves (i.e., combined daytime and nighttime temperature extremes) and their atmospheric drivers over North Africa using reanalysis data and nine CORDEX-CORE regional climate simulations. Compound heatwaves occur 1–2 times per year, last 3–5 days, and exhibit extreme temperature anomalies reaching + 12&#xa0;°C during daytime and + 5&#xa0;°C at night, with enhanced impacts along coastal regions. These events are associated with a 500&#xa0;hPa dipole circulation, with high-pressure systems over either western or eastern North Africa, leading to subsidence and warming. Near the surface, warm air advection from the Sahara enhances heating, while longwave radiation plays a dominant role in maintaining high temperatures. Climate models show regional biases, underestimating compound heatwaves along North African coasts and overestimating them in the central Sahara, with results mainly controlled by the regional climate model. This study improves understanding of compound heatwave mechanisms and supports better heat-risk assessment and regional climate modeling in North Africa.</p>

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Compound Heatwaves in North Africa: Mechanisms and Model Capabilities

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2026年4月20日

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  • Khadija Arjdal,
  • Fatima Driouech,
  • Saloua Balhane,
  • Rodrigo Manzanas

摘要

Climate hazards driven by extreme events have recently gained attention due to their severe environmental and socio-economic impacts. While independent daytime and nighttime heatwaves have been widely studied, compound heatwaves (CHWs) remain poorly documented in Africa. This study provides the first comprehensive assessment of summer CHWs in North Africa, identifying the corresponding dominant atmospheric and surface drivers using reanalysis data and CORDEX-CORE regional climate simulations for the period 1979–2023. Compound heatwaves show strong spatial variability across North Africa, occurring more frequently along the populated coastal regions and less often over mountainous areas such as the Atlas. These events are associated with pronounced temperature anomalies; they tend to develop under a persistent dipole configuration at 500 hPa, characterized by a ridge located either over the western part of the region (Morocco) or over the eastern sector (Egypt). This circulation pattern favors subsidence and adiabatic warming, while warm air advection from the central Sahara further increases near-surface temperatures. Enhanced downward longwave radiation emerges as the dominant radiative contribution to surface warming, whereas solar radiation plays a comparatively secondary role. The assessment of regional climate models’ capabilities shows systematic biases in the representation of these events, generally underestimating their occurrence in coastal and Mediterranean regions while overestimating them over the central Sahara. Our analysis further indicates that the representation of compound heatwaves is more strongly influenced by the regional climate model configuration than by the driving global model. These findings help advance the understanding of compound heatwave dynamics in North Africa and showcase the need to improve their representation in regional climate models. By characterizing the mechanisms related to these events, this study helps support climate risk assessment and adaptation, particularly in light of the increasing impacts of heat extremes on public health, water resources, agriculture, and energy systems across the region.

Graphical Abstract

This study provides the first comprehensive characterization of summer compound heatwaves (i.e., combined daytime and nighttime temperature extremes) and their atmospheric drivers over North Africa using reanalysis data and nine CORDEX-CORE regional climate simulations. Compound heatwaves occur 1–2 times per year, last 3–5 days, and exhibit extreme temperature anomalies reaching + 12 °C during daytime and + 5 °C at night, with enhanced impacts along coastal regions. These events are associated with a 500 hPa dipole circulation, with high-pressure systems over either western or eastern North Africa, leading to subsidence and warming. Near the surface, warm air advection from the Sahara enhances heating, while longwave radiation plays a dominant role in maintaining high temperatures. Climate models show regional biases, underestimating compound heatwaves along North African coasts and overestimating them in the central Sahara, with results mainly controlled by the regional climate model. This study improves understanding of compound heatwave mechanisms and supports better heat-risk assessment and regional climate modeling in North Africa.