Quantifying the physical processes leading to atmospheric hot extremes at a global scale
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Date
2023-03
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Journal Article
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Abstract
Heat waves are among the deadliest climate hazards. Yet the relative importance of the physical processes causing their near-surface temperature anomalies (T′)—advection of air from climatologically warmer regions, adiabatic warming in subsiding air and diabatic heating—is still a
matter of debate. Here we quantify the importance of these processes by evaluating the T′ budget along air-parcel backward trajectories. We frst show that the extreme near-surface T′ during the June 2021 heat wave in western North America was produced primarily by diabatic heating and,
to a smaller extent, by adiabatic warming. Systematically decomposing T′ during the hottest days of each year (TX1day events) in 1979–2020 globally, we fnd strong geographical variations with a dominance of advection over mid-latitude oceans, adiabatic warming near mountain ranges and
diabatic heating over tropical and subtropical land masses. In many regions, however, TX1day events arise from a combination of these processes. In the global mean, TX1day anomalies form along trajectories over roughly 60 h and 1,000 km, although with large regional variability. This study thus
reveals inherently non-local and regionally distinct formation pathways of hot extremes, quantifes the crucial factors determining their magnitude and enables new quantitative ways of climate model evaluation regarding hot extremes.
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16 (3)
Pages / Article No.
210 - 216
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03854 - Wernli, Johann Heinrich / Wernli, Johann Heinrich
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787652 - An integrated weather-system perspective on the characteristics, dynamics and impacts of extreme seasons (EC)