10 Mar 2022
10 Mar 2022
Status: this preprint is currently under review for the journal WCD.

Large discrepancies in the representation of compound long-duration dry and hot spells over Europe in CMIP5

Colin Manning1, Emanuele Bevacqua2, Martin Widmann3, Douglas Maraun4, and Anne F. Van Loon5 Colin Manning et al.
  • 1School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
  • 2Department of Computational Hydrosystems, Helmholtz Centre for Environmental Research—UFZ, Leipzig, Germany
  • 3University of Birmingham, Edgbaston, Birmingham, B152TT, United Kingdom
  • 4Wegener Center for Climate and Global Change, University of Graz, Graz, Austria
  • 5Institute for Environmental Studies (IVM), Vrije Universiteit Amsterdam, Amsterdam, the Netherlands

Abstract. Long-duration dry spells in combination with temperature extremes during summer have led to extreme impacts on society and ecosystems in the past. Such events are expected to become more frequent due to increasing temperatures as a result of anthropogenic climate change. However, there is little information on how long-duration dry and hot spells are represented in global climate models (GCMs). In this study, we evaluate 33 CMIP5 GCMs in their representation of long-duration dry spells and temperatures during dry spells. We define a dry spell as a consecutive number of days with daily precipitation less than 1mm. CMIP5 models tend to underestimate the persistence of dry spells in Northern Europe while a large variability exists between model estimates in Central and Southern Europe where models have contrasting biases. Our results indicate that this variability in model estimates is due to inherent model differences and not internal variability. In Northern Europe, differences in the representation of persistent dry spells are related to the representation of persistent anticyclonic conditions. We also find a large spread in the representation of temperature extremes during dry spells. In Central and Southern Europe this spread in temperature extremes between models is related to the representation of dry spells, where models that produce longer dry spells also produce higher temperatures, and vice versa. Overall, there are large discrepancies in the representation of long-duration dry and hot events in the CMIP5 ensemble where the simulated climates vary from models with shorter-cooler dry spells to models with longer-hotter dry spells. This information is important to consider when interpreting the plausibility of future projections from climate models.

Colin Manning et al.

Status: open (until 03 Jun 2022)

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  • RC1: 'Comment on wcd-2022-15', Anonymous Referee #1, 14 Apr 2022 reply

Colin Manning et al.

Colin Manning et al.


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Short summary
This article shows that climate models largely differ in their representation of persistent dry spells that co-occur with extremely high temperatures. Some models simulate dry spells that are too short and too cool compared to observations, while others simulate dry spells that are too long and too hot. This information is important when interpreting the likelihood of such events in a warmer climate so that we can assess the plausibility of their future projections.