Future heat extremes and impacts in a convection permitting climate ensemble over Germany
Abstract. Heat extremes and associated impacts are considered the most pressing issue for German regional governments with respect to climate adaptation. We explore the potential of an unique high-resolution convection permitting (2.8 km), multi-GCM ensemble with COSMO-CLM regional simulations (1971–2100) over Germany regarding heat extremes and related impacts. We find an improved mean temperature beyond the effect of a better representation of orography on the convection permitting scale, with reduced bias particularly during summer. The projected increase in temperature and its variance favors the development of longer and hotter heat waves, especially in late summer and early autumn. In a 2° (3°) warmer world, a 26 % (100 %) increase in the Heat Wave Magnitude Index is anticipated. Human heat stress (UTCI > 32°C) and local-specific parameters tailored to climate adaptation, revealed a dependency on the major landscapes, resulting in significant higher heat exposure in flat regions as the Rhine Valley, accompanied by the strongest absolute increase. A non-linear, exponential increase is anticipated for parameters characterizing strong heat stress (UTCI > 32°C, tropical nights, very hot days). Providing local-specific and tailored climate information, we demonstrate the potential of convection permitting simulations to facilitate improved impact studies and narrow the gap between climate modelling and stakeholder requirements for climate adaptation.
Marie Hundhausen et al.
Status: final response (author comments only)
RC1: 'Comment on nhess-2022-283', Anonymous Referee #1, 27 Jan 2023
- AC1: 'Reply on RC1', Marie Hundhausen, 24 Mar 2023
RC2: 'Comment on nhess-2022-283', Anonymous Referee #2, 31 Jan 2023
- AC2: 'Reply on RC2', Marie Hundhausen, 24 Mar 2023
Marie Hundhausen et al.
Marie Hundhausen et al.
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The present manuscript analyses temperature extremes and associated impacts through a high-resolution convection-permitting (2.8 km), multi-GCM ensemble with COSMO-CLM regional simulations from 1971 to 2100 over Germany. The study points out a projected increase in temperature and its variance combined with hotter and more lasting heat waves. The analysis also considers a comprehensive set of heat stress and user-tailored climate indices.
The research is surely relevant in terms of temperature extremes analysis and also for considering for the first time a multi-GCM ensemble of convection-permitting (CP) climate simulations over a multi-decadal time period.
The topic is surely fitting with the scope of the journal but different relevant aspects mainly pertaining to the methodological choices and technical aspects related to the simulations performed and analyzed in the study deserve clarification before being reconsidered for publication in NHESS journal.
Line 4. “We find an improved mean temperature beyond the effect of a better representation of orography on the convection-permitting scale, with reduced bias, particularly during summer”. I do not believe that the manuscript analyses allow us to reach such a conclusion.
The caption of Figure 1. To me it results quite complicated to understand, please rephrase. Especially: “Nesting in (a) and model domain”
Section 2.2 should be improved (see general comments.).
Line 152. “user-oriented parameterizations are tested”. Please explain what you mean in this statement.
Lines 172-174. To me is not cleat the meaning of “reference humidity is constant at 20hPa” is. Please clarify.
Line 187. Please correct the quote's typo.
Figure 3. Instead of monthly means, I would rather compare the five daily temperature distributions (e.g., boxplots) or a percentile-based error to see which part of the distribution benefits the most from the higher resolution during the different parts of the year.
Line 208. Please clarify how the Wilcoxon test is applied in this context.
Line 210. Why is talk about trends here? This sentence is not clear to me.
Figure 4 caption. (c) appears twice.
Line 239. “Average variance” Perhaps ensemble variance?
Line 252. Please clarify the meaning of “the full width of half maximum (FWHM)”.
Figure 6. Why change color bar limits and colormap between (a) and (c) panels?
Heat wave characterization results section is quite loosely described, I would suggest better discussing this part.
Figure 7. caption, the description of the panel (d) is not clear to me. Also, PDFs are not described.
Discussion and conclusion section. Here it should be clarified how the CP-scale and/or the bias correction contribute to the reported improvement of temperature extremes representation.