the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
The European summer heatwave 2019 – a regional storyline perspective
Abstract. The number and intensity of heat waves have increased in the recent past, along with anthropogenic climate change. This poses challenges to many communities and raises the need to develop adaptation measures based on more accurate information regarding regional to local changes in temperature extremes and their impacts. While the general increase in global mean temperature is well established, current global climate projections show a large model spread regarding possible future circulation changes. To isolate the more certain thermodynamic response from the less certain dynamical response to anthropogenic climate change, we employ an event-based storyline approach comprising three steps. Firstly, the large-scale circulation in the free troposphere was spectrally nudged to the ERA5-reanalyses in the global coupled climate model AWI-CM-1.1-MR for a recent period (2017–2022), corresponding to +1.4 K global warming, and repeated under pre-industrial, +2 K, +3 K, and +4 K global warming climates. Secondly, the global storylines were dynamically downscaled with the regional ICON-CLM model to the Euro-CORDEX domain with a horizontal resolution of 12 km and, thirdly, to a Central-European (German) domain with a resolution of 3 km. The present study focuses on the 2019 summer heatwaves over Central Europe. We demonstrate the added value of downscaling global storyline integrations, indicating a significant improvement in present-day temperature patterns and a reduced error in daily 2 m temperature relative to observations in Central Europe. The magnitude of the heatwave temperature response significantly exceeds the globally modelled background warming, with a distinct spatial and temporal variation in the regional increments. Our simulations indicate a general linear dependency of the 2 m temperature response to the global warming level: the warming rates during the July 2019 heatwave ranged between factors of 2 and 3 in Central Europe, resulting in an anthropogenic warming of 8 to 12 °C in the +4 K climate. The spatial extent and the duration of the heat wave are also amplified in the warmer climates. With this three-step downscaling approach, we gain new insights into possible future changes in heat extremes in Central Europe, which apparently surpass global warming trends. Along with its scientific value, our method provides ways to facilitate communication of regional climate change information to the users.
- Preprint
(11863 KB) - Metadata XML
-
Supplement
(10122 KB) - BibTeX
- EndNote
Status: closed
-
RC1: 'Comment on esd-2024-16', Anonymous Referee #1, 15 Aug 2024
GENERAL COMMENTS
The study uses spectrally nudged high-resolution regional climate model simulations to quantify the sensitivity of summer 2019 European heatwave to the thermodynamic effects of global warming. The simulations indicate that, under unchanged atmospheric circulation, the daily maximum temperatures experienced under the heatwaves increase by about 2 K for each 1 K of global mean temperature change, and locally up to 3 K to the east of the heatwave centre. This contrasts with the simulated temperatures earlier in the summer, which only increase at the same rate with the global mean temperature. These features, together with the increased diurnal temperature range during the heatwave periods, suggest a role for reduced soil moisture in the amplified temperature response.
Overall, the manuscript is interesting and well-written. I only have a few minor comments and remarks on it.
DETAILED COMMENTS (substance and presentation)
- The focus of the study should be introduced earlier. Perhaps write on L7: ... we employ an event-based storyline approach to study the 2019 summer heatwaves over Central Europe. The approach comprises three steps ....
- "the scaling of the global mean temperature" is obscure: the global mean temperature always scales one-to-one with itself.
- Equation (2) suggests a linear increase with height.
- L148-149. The ensemble spread in E-OBS characterizes the observational uncertainty in individual daily temperature fields. The observational uncertainty in (e.g.) summer mean values is expected to be considerably smaller, due to cancellation of errors whose sign varies from day to day. For this reason, comparison with the E-OBS ensemble spread understates the significance of the model-to-observation biases on longer than daily time scales.
- L237-238. The difference in warming rates might also relate to the difference in season (early vs. late summer), not only the extremeness of temperature.
- L274-277. Is the mean scaling similar for all summer months, or does it increase from early to late summer following the decrease in average soil moisture?
- Same as comment 2.
- L339-341. Is this seasonal evolution of the diurnal temperature range change specific to summer 2019, or does it also occur in the other simulated years?
DETAILED COMMENTS (wording and typos)
- aimed at estimating the effect of human-induced …
- L34-35. contributions to
- computationally efficient
- L70 and later. spectrally nudged
- and 8-20 km in the Arctic
- Caption of Figure 3, L3. give / report the RMSD to E-OBS
- Analogously to
- the GER-3 simulation
- L221-222. the longitude-latitude area
- to the east of it?
Citation: https://doi.org/10.5194/esd-2024-16-RC1 - AC1: 'Reply on RC1', Tatiana Klimiuk, 20 Sep 2024
-
RC2: 'Comment on esd-2024-16', Anonymous Referee #2, 28 Aug 2024
The comment was uploaded in the form of a supplement: https://esd.copernicus.org/preprints/esd-2024-16/esd-2024-16-RC2-supplement.pdf
- AC2: 'Reply on RC2', Tatiana Klimiuk, 27 Sep 2024
Status: closed
-
RC1: 'Comment on esd-2024-16', Anonymous Referee #1, 15 Aug 2024
GENERAL COMMENTS
The study uses spectrally nudged high-resolution regional climate model simulations to quantify the sensitivity of summer 2019 European heatwave to the thermodynamic effects of global warming. The simulations indicate that, under unchanged atmospheric circulation, the daily maximum temperatures experienced under the heatwaves increase by about 2 K for each 1 K of global mean temperature change, and locally up to 3 K to the east of the heatwave centre. This contrasts with the simulated temperatures earlier in the summer, which only increase at the same rate with the global mean temperature. These features, together with the increased diurnal temperature range during the heatwave periods, suggest a role for reduced soil moisture in the amplified temperature response.
Overall, the manuscript is interesting and well-written. I only have a few minor comments and remarks on it.
DETAILED COMMENTS (substance and presentation)
- The focus of the study should be introduced earlier. Perhaps write on L7: ... we employ an event-based storyline approach to study the 2019 summer heatwaves over Central Europe. The approach comprises three steps ....
- "the scaling of the global mean temperature" is obscure: the global mean temperature always scales one-to-one with itself.
- Equation (2) suggests a linear increase with height.
- L148-149. The ensemble spread in E-OBS characterizes the observational uncertainty in individual daily temperature fields. The observational uncertainty in (e.g.) summer mean values is expected to be considerably smaller, due to cancellation of errors whose sign varies from day to day. For this reason, comparison with the E-OBS ensemble spread understates the significance of the model-to-observation biases on longer than daily time scales.
- L237-238. The difference in warming rates might also relate to the difference in season (early vs. late summer), not only the extremeness of temperature.
- L274-277. Is the mean scaling similar for all summer months, or does it increase from early to late summer following the decrease in average soil moisture?
- Same as comment 2.
- L339-341. Is this seasonal evolution of the diurnal temperature range change specific to summer 2019, or does it also occur in the other simulated years?
DETAILED COMMENTS (wording and typos)
- aimed at estimating the effect of human-induced …
- L34-35. contributions to
- computationally efficient
- L70 and later. spectrally nudged
- and 8-20 km in the Arctic
- Caption of Figure 3, L3. give / report the RMSD to E-OBS
- Analogously to
- the GER-3 simulation
- L221-222. the longitude-latitude area
- to the east of it?
Citation: https://doi.org/10.5194/esd-2024-16-RC1 - AC1: 'Reply on RC1', Tatiana Klimiuk, 20 Sep 2024
-
RC2: 'Comment on esd-2024-16', Anonymous Referee #2, 28 Aug 2024
The comment was uploaded in the form of a supplement: https://esd.copernicus.org/preprints/esd-2024-16/esd-2024-16-RC2-supplement.pdf
- AC2: 'Reply on RC2', Tatiana Klimiuk, 27 Sep 2024
Viewed
HTML | XML | Total | Supplement | BibTeX | EndNote | |
---|---|---|---|---|---|---|
613 | 82 | 232 | 927 | 39 | 16 | 16 |
- HTML: 613
- PDF: 82
- XML: 232
- Total: 927
- Supplement: 39
- BibTeX: 16
- EndNote: 16
Viewed (geographical distribution)
Country | # | Views | % |
---|
Total: | 0 |
HTML: | 0 |
PDF: | 0 |
XML: | 0 |
- 1