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Figure A2. As figure 2 but for HWMId calculated with daily minimum temperatures.

Figure 2 A2. As figure 2 but for HWMId calculated with daily minimum temperatures.

Related Figures (10)

Figure 1. HWMId and HWMI calculation at a station in Carcassonne (Southern France). (a) E-OBS time serie of the year 2003 of daily maximum temperature in Carcassonne located in Southern France (open gray circles and blue letters) and daily threshold (black line). The blue letters, represent the daily maximum temperature values of the 2003 heatwave experienced in Carcassonne and indicated as HW1. The green letters, are the daily maximum temperature values of the HW2 heatwave obtained by adding 5 °C to each temperature of the 2003 heatwave HW1. As HW1, HW2 is composed by 4 sub-heatwaves represented by green letters a, b, c, d. (b) The dashed black line is the Mj function used to calculate the HWMId daily magnitude (see equation (2)), the black line denotes the empirical distribution of the sum of the three highest consecutive daily maximum temperatures of each year within the reference period 1981-2010 used in the HWMI calculation (see Russo et al 2014). Blue and green letters refer to each single day (left) or to each sub-heatwave (right) of the HW1 and HW2 heatwaves, respectively.
Figure 1. HWMId and HWMI calculation at a station in Carcassonne (Southern France). (a) E-OBS time serie of the year 2003 of daily maximum temperature in Carcassonne located in Southern France (open gray circles and blue letters) and daily threshold (black line). The blue letters, represent the daily maximum temperature values of the 2003 heatwave experienced in Carcassonne and indicated as HW1. The green letters, are the daily maximum temperature values of the HW2 heatwave obtained by adding 5 °C to each temperature of the 2003 heatwave HW1. As HW1, HW2 is composed by 4 sub-heatwaves represented by green letters a, b, c, d. (b) The dashed black line is the Mj function used to calculate the HWMId daily magnitude (see equation (2)), the black line denotes the empirical distribution of the sum of the three highest consecutive daily maximum temperatures of each year within the reference period 1981-2010 used in the HWMI calculation (see Russo et al 2014). Blue and green letters refer to each single day (left) or to each sub-heatwave (right) of the HW1 and HW2 heatwaves, respectively.
Figure 2. (a) Spatial distribution of the HWMId observed (E-OBS) values and spotted news of the top 10 European heatwaves since 1950; following the definition in section 2.1, at each grid point, the HWMId values represent the yearly maximum magnitude. (b) HWMId estimation with EOBS data from January to September 2015 for the most recent heatwave.
Figure 2. (a) Spatial distribution of the HWMId observed (E-OBS) values and spotted news of the top 10 European heatwaves since 1950; following the definition in section 2.1, at each grid point, the HWMId values represent the yearly maximum magnitude. (b) HWMId estimation with EOBS data from January to September 2015 for the most recent heatwave.
Table 1. List of record-breaking heatwave events in the period 1950-2014 with E-OBS data including also data until September 2015 for the most recent heatwave. The latter is an additional information to the originally considered top 10 heatwaves. For each specific event the spatial extent is estimated as the land area fraction exceeding a fixed HWMId value. The area fraction is expressed in percentage. The HWMId peak is the highest spatial HWMId value recorded during each specific event.
Table 1. List of record-breaking heatwave events in the period 1950-2014 with E-OBS data including also data until September 2015 for the most recent heatwave. The latter is an additional information to the originally considered top 10 heatwaves. For each specific event the spatial extent is estimated as the land area fraction exceeding a fixed HWMId value. The area fraction is expressed in percentage. The HWMId peak is the highest spatial HWMId value recorded during each specific event.
Figure 3. Empirical probability and cumulative distirbution functions (EPDFs and ECDFs) of the percentage land area in heatwaves. (a) Percentage of EURO-CORDEX land area covered by HWMId maximum values greater than a given magnitude level (HWMId > 6,9,..., 24) for the 2003, 1972, and 2010 European heatwaves with E-OBS data (black) and for the strongest heatwave simulated by each individual model in the periods 1981-2010 and 2011-2040. The numbers from 0 to 9 refer to heatwaves simulated by individual models (see table A. 1). Hence, as an example, at each HWMId level the heatwave with the strongest magnitude and spatial extent simulated by the model 0, in 2011-2040 and under the RCP8.5 scenario, is represented by the red symbol 0. (b) PDFs of the percentage land area covered by grid points with HWMId values equal to or greater than 15. The PDFs are shown for the period 1981-2010 (blue curves) and 2011-2040 under RCP4.5 (green curves) and RCP8.5 (red curves) scenarios. The transparent couloured lines mark individual EURO-CORDEX models, comprised of 30 year values, whereas the bold colored curves represent the PDFs comprised ofall 300 (30 years X 10 models) model years. Dotted and dashed lines denote the observed (E-OBS) 2003 and 2010 events, respectively. (c) As (b) but for ECDF of 300 model years. Each open circle represent the percentage of area (value on x-axis) and the corresponding probability for a single model year. The horizontal dashed and dotted lines denote the probability to have 2003 and 2010 type heatwave in 30 year period and under a specific scenario. (d) Percentage of area versus different HWMId levels. The open colored circles and the error bars represent the median and the range of the bootstrap applied at each HWMId level to the ECDF of 300 model years (see panel (c) for HWMId > 15). (e) Occurrence of a 2003-type heatwave in present and near future periods of 30 year simulated by each model according to the ranking method in section 2.8.
Figure 3. Empirical probability and cumulative distirbution functions (EPDFs and ECDFs) of the percentage land area in heatwaves. (a) Percentage of EURO-CORDEX land area covered by HWMId maximum values greater than a given magnitude level (HWMId > 6,9,..., 24) for the 2003, 1972, and 2010 European heatwaves with E-OBS data (black) and for the strongest heatwave simulated by each individual model in the periods 1981-2010 and 2011-2040. The numbers from 0 to 9 refer to heatwaves simulated by individual models (see table A. 1). Hence, as an example, at each HWMId level the heatwave with the strongest magnitude and spatial extent simulated by the model 0, in 2011-2040 and under the RCP8.5 scenario, is represented by the red symbol 0. (b) PDFs of the percentage land area covered by grid points with HWMId values equal to or greater than 15. The PDFs are shown for the period 1981-2010 (blue curves) and 2011-2040 under RCP4.5 (green curves) and RCP8.5 (red curves) scenarios. The transparent couloured lines mark individual EURO-CORDEX models, comprised of 30 year values, whereas the bold colored curves represent the PDFs comprised ofall 300 (30 years X 10 models) model years. Dotted and dashed lines denote the observed (E-OBS) 2003 and 2010 events, respectively. (c) As (b) but for ECDF of 300 model years. Each open circle represent the percentage of area (value on x-axis) and the corresponding probability for a single model year. The horizontal dashed and dotted lines denote the probability to have 2003 and 2010 type heatwave in 30 year period and under a specific scenario. (d) Percentage of area versus different HWMId levels. The open colored circles and the error bars represent the median and the range of the bootstrap applied at each HWMId level to the ECDF of 300 model years (see panel (c) for HWMId > 15). (e) Occurrence of a 2003-type heatwave in present and near future periods of 30 year simulated by each model according to the ranking method in section 2.8.
Figure 4. As figures 3(a), (d), (e) but for HWMId applied to Tmin (see section 2.2). (a) The strongest heatwave in 30 year period with Tmin simulated by each model (0, 1, 2, etc ...) are coherent in space and time with those in figure 3(a). (For more details see also figures 5 and A4). (b) and (c) Colors indicate the same periods and scenarios as in figure 3(a). 4. Model evaluation (1981-2010) But are the models able to simulate heatwaves of the magnitude of those in 2003 and 2010 to provide a reli- able estimate of future summer climate (Beniston 2004, Fischer and Schar 2010, Diffenbaugh and Scherer 2011, Quesada et al 2012)? The simulated HWMId values in a thirty year period (1981-2010) representing present-day climate show that many models at different HWMId levels capture a 2003-type heatwave in the period 1981-2010, withonly one out of ten models simulating, at each HWMId level, a heatwave greater in spatial extent than observed in the 2003 (figures 3(a), 5(a): model4 ). The corresponding HWMId applied to Tmin for the heatwaves in figure 3(a) show similar results, with three out of ten models simulating, at each HWM Id level, a heatwave greater in spatial extent than observed in tl he 2003 (figures 4(a) and (c), see mode sl, 4, 7). None of the models is able to capture the spatial extent of the HWM1Id leve 2010 Russian heatwave at anyone of . (see figures 3(a), 5(a)). When using d Tmin, only one model (figure 4(a), see model 4) at ferent magnitude levels shows a spatial area greater than that measured in the 2010. the aily dif- We use an ensemble of 10 RCMs (see methods) to evaluate the simulated heatwave magnitude and extent against observations. Heatwaves in the same set of RCMs but driven by reanalysis data, have been evaluated in a recent study (Vautard et al 2013) showing that most models exhibit an overestimation of summertime observed temperature extremes in Mediterranian regions and an underestimation over Scandinavia. They show that if heatwaves in the model are defined with respect to the observed percentiles, their persistence is directly influenced by this bias. In fact, a model that overestimates the 90th percentile threshold of the simulated temperature with respect to the observations will show an obvious overestimation of heatwave duration. This effect is corrected in the previous study (Vautard et al 2013) and here by HWMId defining a heatwave as a period of consecutive hot days with daily Tmax above the 90th percentile threshold of the respective model and not with respect to the observa- tions. The implicit bias correction included in HWMId calculation, gives high skill to this index in comparing heatwaves simulated by different climate models. All the models simulate heatwaves in northern, Southern, East- ern, and Western Europe and in particular over the regions where the top ten heatwaves occurred in the present (figure 5(a)).
Figure 4. As figures 3(a), (d), (e) but for HWMId applied to Tmin (see section 2.2). (a) The strongest heatwave in 30 year period with Tmin simulated by each model (0, 1, 2, etc ...) are coherent in space and time with those in figure 3(a). (For more details see also figures 5 and A4). (b) and (c) Colors indicate the same periods and scenarios as in figure 3(a). 4. Model evaluation (1981-2010) But are the models able to simulate heatwaves of the magnitude of those in 2003 and 2010 to provide a reli- able estimate of future summer climate (Beniston 2004, Fischer and Schar 2010, Diffenbaugh and Scherer 2011, Quesada et al 2012)? The simulated HWMId values in a thirty year period (1981-2010) representing present-day climate show that many models at different HWMId levels capture a 2003-type heatwave in the period 1981-2010, withonly one out of ten models simulating, at each HWMId level, a heatwave greater in spatial extent than observed in the 2003 (figures 3(a), 5(a): model4 ). The corresponding HWMId applied to Tmin for the heatwaves in figure 3(a) show similar results, with three out of ten models simulating, at each HWM Id level, a heatwave greater in spatial extent than observed in tl he 2003 (figures 4(a) and (c), see mode sl, 4, 7). None of the models is able to capture the spatial extent of the HWM1Id leve 2010 Russian heatwave at anyone of . (see figures 3(a), 5(a)). When using d Tmin, only one model (figure 4(a), see model 4) at ferent magnitude levels shows a spatial area greater than that measured in the 2010. the aily dif- We use an ensemble of 10 RCMs (see methods) to evaluate the simulated heatwave magnitude and extent against observations. Heatwaves in the same set of RCMs but driven by reanalysis data, have been evaluated in a recent study (Vautard et al 2013) showing that most models exhibit an overestimation of summertime observed temperature extremes in Mediterranian regions and an underestimation over Scandinavia. They show that if heatwaves in the model are defined with respect to the observed percentiles, their persistence is directly influenced by this bias. In fact, a model that overestimates the 90th percentile threshold of the simulated temperature with respect to the observations will show an obvious overestimation of heatwave duration. This effect is corrected in the previous study (Vautard et al 2013) and here by HWMId defining a heatwave as a period of consecutive hot days with daily Tmax above the 90th percentile threshold of the respective model and not with respect to the observa- tions. The implicit bias correction included in HWMId calculation, gives high skill to this index in comparing heatwaves simulated by different climate models. All the models simulate heatwaves in northern, Southern, East- ern, and Western Europe and in particular over the regions where the top ten heatwaves occurred in the present (figure 5(a)).
Figure 5. Spatial distribution of the HWMId values of the strongest heatwave in a 30 year period simulated by each of the ten models in a specific model-year. (a) present period (1981-2010) in the historical simulations (1981-2005) and RCP4.5 (2006-2010). (b) and (c) Next two decades (2011-2040) under the RCP4.5 and RCP8.5 scenarios, respectively.
Figure 5. Spatial distribution of the HWMId values of the strongest heatwave in a 30 year period simulated by each of the ten models in a specific model-year. (a) present period (1981-2010) in the historical simulations (1981-2005) and RCP4.5 (2006-2010). (b) and (c) Next two decades (2011-2040) under the RCP4.5 and RCP8.5 scenarios, respectively.
Figure A1. Spatial distribution of the HWMI observed (E-OBS) values of the top 10 European heatwaves since 1950.
Figure A1. Spatial distribution of the HWMI observed (E-OBS) values of the top 10 European heatwaves since 1950.
Table A.1. List of the ten EURO-CORDEX used models.
Table A.1. List of the ten EURO-CORDEX used models.
Figure A3. Temperature anomaly calculated following the definition in section 2.6 and heatwave duration of the top 10 European heatwaves and of the most recent heatwave of summer 2015.
Figure A3. Temperature anomaly calculated following the definition in section 2.6 and heatwave duration of the top 10 European heatwaves and of the most recent heatwave of summer 2015.
Figure A4. As figure 5 but for HWMId calculated with Tmin in the same model year of the strongest heatwaves represented in figure 5.
Figure A4. As figure 5 but for HWMId calculated with Tmin in the same model year of the strongest heatwaves represented in figure 5.
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European StudiesClimate ChangeHeat WavesWeather Extremes
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