EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

On the connection between heat waves and large deviations of temperature

Jeroen Wouters1, Vera Melinda Galfi2, and Valerio Lucarini1
Jeroen Wouters et al.
  • 1University of Reading, Department of Mathematics & Statistics, Reading, United Kingdom of Great Britain and Northern Ireland (
  • 2Meteorological Institute, CEN, University of Hamburg, Hamburg, Germany

We use large deviation theory to study persistent extreme events of temperature, like heat waves or cold spells. We consider the mid-latitudes of a simplified yet Earth-like general circulation model of the atmosphere and numerically estimate large deviation rate functions of near-surface temperature averages over different spatial scales. We find that, in order to represent persistent extreme events based on large deviation theory, one has to look at temporal averages of spatially averaged observables. The spatial averaging scale is crucial, and has to correspond with the scale of the event of interest. Accordingly, the computed rate functions indicate substantially different statistical properties of temperature averages over intermediate spatial scales (larger, but still of the order of the typical scale), as compared to the ones related to any other scale. Thus, heat waves (or cold spells) can be interpreted as large deviations of temperature averaged over intermediate spatial scales. Furthermore, we find universal characteristics of rate functions, based on the equivalence of temporal, spatial, and spatio-temporal rate functions if we perform a re-normalisation by the integrated auto-correlation.

How to cite: Wouters, J., Galfi, V. M., and Lucarini, V.: On the connection between heat waves and large deviations of temperature, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7336,, 2020

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