Scaling precipitation extremes with temperature in the Mediterranean: past climate assessment and projection in anthropogenic scenarios

Climate Dynamics, Mar 2016

In this study we investigate the scaling of precipitation extremes with temperature in the Mediterranean region by assessing against observations the present day and future regional climate simulations performed in the frame of the HyMeX and MED-CORDEX programs. Over the 1979–2008 period, despite differences in quantitative precipitation simulation across the various models, the change in precipitation extremes with respect to temperature is robust and consistent. The spatial variability of the temperature–precipitation extremes relationship displays a hook shape across the Mediterranean, with negative slope at high temperatures and a slope following Clausius–Clapeyron (CC)-scaling at low temperatures. The temperature at which the slope of the temperature–precipitation extreme relation sharply changes (or temperature break), ranges from about 20 °C in the western Mediterranean to <10 °C in Greece. In addition, this slope is always negative in the arid regions of the Mediterranean. The scaling of the simulated precipitation extremes is insensitive to ocean–atmosphere coupling, while it depends very weakly on the resolution at high temperatures for short precipitation accumulation times. In future climate scenario simulations covering the 2070–2100 period, the temperature break shifts to higher temperatures by a value which is on average the mean regional temperature change due to global warming. The slope of the simulated future temperature–precipitation extremes relationship is close to CC-scaling at temperatures below the temperature break, while at high temperatures, the negative slope is close, but somewhat flatter or steeper, than in the current climate depending on the model. Overall, models predict more intense precipitation extremes in the future. Adjusting the temperature–precipitation extremes relationship in the present climate using the CC law and the temperature shift in the future allows the recovery of the temperature–precipitation extremes relationship in the future climate. This implies negligible regional changes of relative humidity in the future despite the large warming and drying over the Mediterranean. This suggests that the Mediterranean Sea is the primary source of moisture which counteracts the drying and warming impacts on relative humidity in parts of the Mediterranean region.

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Scaling precipitation extremes with temperature in the Mediterranean: past climate assessment and projection in anthropogenic scenarios

Climate Dynamics August 2018, Volume 51, Issue 3, pp 1237–1257 | Cite as Scaling precipitation extremes with temperature in the Mediterranean: past climate assessment and projection in anthropogenic scenarios AuthorsAuthors and affiliations Philippe DrobinskiNicolas Da SilvaGérémy PanthouSophie BastinCaroline MullerBodo AhrensMarco BorgaDario ConteGiorgia FosserFilippo GiorgiIvan GüttlerVassiliki KotroniLaurent LiEfrat MorinBariş ÖnolPere Quintana-SeguiRaquel RomeraCsaba Zsolt Torma Open Access Article First Online: 26 March 2016 5 Shares 3k Downloads 12 Citations Abstract In this study we investigate the scaling of precipitation extremes with temperature in the Mediterranean region by assessing against observations the present day and future regional climate simulations performed in the frame of the HyMeX and MED-CORDEX programs. Over the 1979–2008 period, despite differences in quantitative precipitation simulation across the various models, the change in precipitation extremes with respect to temperature is robust and consistent. The spatial variability of the temperature–precipitation extremes relationship displays a hook shape across the Mediterranean, with negative slope at high temperatures and a slope following Clausius–Clapeyron (CC)-scaling at low temperatures. The temperature at which the slope of the temperature–precipitation extreme relation sharply changes (or temperature break), ranges from about 20 °C in the western Mediterranean to <10 °C in Greece. In addition, this slope is always negative in the arid regions of the Mediterranean. The scaling of the simulated precipitation extremes is insensitive to ocean–atmosphere coupling, while it depends very weakly on the resolution at high temperatures for short precipitation accumulation times. In future climate scenario simulations covering the 2070–2100 period, the temperature break shifts to higher temperatures by a value which is on average the mean regional temperature change due to global warming. The slope of the simulated future temperature–precipitation extremes relationship is close to CC-scaling at temperatures below the temperature break, while at high temperatures, the negative slope is close, but somewhat flatter or steeper, than in the current climate depending on the model. Overall, models predict more intense precipitation extremes in the future. Adjusting the temperature–precipitation extremes relationship in the present climate using the CC law and the temperature shift in the future allows the recovery of the temperature–precipitation extremes relationship in the future climate. This implies negligible regional changes of relative humidity in the future despite the large warming and drying over the Mediterranean. This suggests that the Mediterranean Sea is the primary source of moisture which counteracts the drying and warming impacts on relative humidity in parts of the Mediterranean region. KeywordsPrecipitation extremes Clausius–Clapeyron scaling  Regional climate Europe Mediterranean HyMeX MED-CORDEX  This paper is a contribution to the special issue on Med-CORDEX, an international coordinated initiative dedicated to the multi-component regional climate modelling (atmosphere, ocean, land surface, river) of the Mediterranean under the umbrella of HyMeX, CORDEX, and Med-CLIVAR and coordinated by Samuel Somot, Paolo Ruti, Erika Coppola, Gianmaria Sannino, Bodo Ahrens, and Gabriel Jordà. 1 Introduction The complex geography of the Mediterranean region, which features a nearly enclosed sea with high sea surface temperature during summer and fall surrounded by mountains (Fig. 1), plays a crucial role in steering airflow producing heavy precipitation and catastrophic floods (e.g. Delrieu et al. 2005; Jonkman 2005; Ducrocq et al. 2008; Papagiannaki et al. 2013). In the last 50 years significant increasing trends in daily torrential rains was observed in some western Mediterranean regions, while in the east relatively high interannual variability prevents any trend from being significant (Alpert et al. 2002). Open image in new window Fig. 1 Target region of the HyMeX/MED-CORDEX regional climate simulations with colors indicating the topography and white circles the locations of the weather stations used in this study Precipitation extremes and flash floodings are among the most devastating natural hazards in terms of mortality (e.g. Jonkman 2005). Even if flash floods are usually small-scale events, their suddenness and violence account for the high proportion of human losses. According to Jonkman (2005), the European and African continents display the highest mortality rates due to floods or flash floods in the world. Precipitation intensity is projected to increase in most regions under warmer climates, and the increase in precipitation extremes will be larger than that in the mean precipitation (Meehl et al. 2007), with large impacts on society (Oki and Kanae 2006; Pall et al. 2011; (...truncated)


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Philippe Drobinski, Nicolas Da Silva, Gérémy Panthou, Sophie Bastin, Caroline Muller, Bodo Ahrens, Marco Borga, Dario Conte, Giorgia Fosser, Filippo Giorgi, Ivan Güttler, Vassiliki Kotroni, Laurent Li, Efrat Morin, Bariş Önol, Pere Quintana-Segui, Raquel Romera, Csaba Zsolt Torma. Scaling precipitation extremes with temperature in the Mediterranean: past climate assessment and projection in anthropogenic scenarios, Climate Dynamics, 2016, pp. 1237-1257, Volume 51, Issue 3, DOI: 10.1007/s00382-016-3083-x