Preprints
https://doi.org/10.5194/egusphere-2024-2540
https://doi.org/10.5194/egusphere-2024-2540
02 Sep 2024
 | 02 Sep 2024

Global relevance of atmospheric and land surface drivers for hot temperature extremes

Yigit Uckan, Melissa Ruiz-Vásquez, Kelley De Polt, and René Orth

Abstract. Hot temperature extremes have severe impacts on society and ecosystems. Their magnitude and frequency are increasing with climate change in most regions globally. These extremes are driven by both atmospheric and land surface processes such as advection or reduced evaporative cooling. The contributions of the individual drivers to the formation and evolution of hot extremes have been analyzed in case studies for major past events, but the global relevance of drivers still remains unclear. In this study, we determine the relevance of (i) atmospheric drivers such as wind, geopotential height, geopotential height differences and surface net radiation, as well as (ii) land surface drivers such as evaporative fraction and enhanced vegetation index for hot extremes across the globe using observation-based data. Hot extremes are identified at daily and weekly time scales through the highest absolute temperature and an analogue-based approach to determine the relevance of the considered drivers. The results show that geopotential height at 500 hPa is overall the most relevant driver of hot extremes across the globe. Surface net radiation and enhanced vegetation index are the second most relevant drivers in many regions, particularly in tropical and semi-arid areas. We find that the relevance of land surface drivers is increasing within the studied period, and from daily to weekly durations. Revealing key regions and influential time scales of land surface drivers on hot extremes can inform more efficient prediction and management of the increasing threat these extremes pose.

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Yigit Uckan, Melissa Ruiz-Vásquez, Kelley De Polt, and René Orth

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on egusphere-2024-2540', Knut Seip, 02 Sep 2024
    • AC4: 'Reply on CC1', Yigit Uckan, 11 Nov 2024
  • RC1: 'Comment on egusphere-2024-2540', Anonymous Referee #1, 02 Oct 2024
    • AC1: 'Reply on RC1', Yigit Uckan, 11 Nov 2024
  • CC2: 'Comment on egusphere-2024-2540', Knut Seip, 06 Oct 2024
    • AC3: 'Reply on CC2', Yigit Uckan, 11 Nov 2024
  • RC2: 'Comment on egusphere-2024-2540', Paul Dirmeyer, 08 Oct 2024
    • AC2: 'Reply on RC2', Yigit Uckan, 11 Nov 2024
Yigit Uckan, Melissa Ruiz-Vásquez, Kelley De Polt, and René Orth
Yigit Uckan, Melissa Ruiz-Vásquez, Kelley De Polt, and René Orth

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Short summary
Drivers of hot extremes are not well known on a global scale. Here, we show the global distribution and relevance of these drivers. Our results show that atmospheric circulation is the most critical driver of hot extremes, particularly in the mid-latitudes. Land surface factors, such as vegetation and radiation, are important in tropical and semi-arid regions. Understanding the relative contributions of atmospheric and land surface drivers of hot extremes can help improve predictions.