TY - JOUR A1 - Bürger, Gerd A1 - Pfister, A. A1 - Bronstert, Axel T1 - Temperature-Driven Rise in Extreme Sub-Hourly Rainfall JF - Journal of climate N2 - Estimates of present and future extreme sub-hourly rainfall are derived from a daily spatial followed by a sub-daily temporal downscaling, the latter of which incorporates a novel, and crucial, temperature sensitivity. Specifically, daily global climate fields are spatially downscaled to local temperature T and precipitation P, which are then disaggregated to a temporal resolution of 10 min using a multiplicative random cascade model. The scheme is calibrated and validated with a group of 21 station records of 10-min resolution in Germany. The cascade model is used in the classical (denoted as MC) and in the new T-sensitive (MC+) version, which respects local Clausius-Clapeyron (CC) effects such as CC scaling. Extreme P is positively biased in both MC versions. Observed T sensitivity is absent in MC but well reproduced by MC+. Long-term positive trends in extreme sub-hourly P are generally more pronounced and more significant in MC+ than in MC. In units of 10-min rainfall, observed centennial trends in annual exceedance counts (EC) of P > 5 mm are +29% and in 3-yr return levels (RL) +27%. For the RCP4.5-simulated future, higher extremes are projected in both versions MC and MC+: per century, EC increases by 30% for MC and by 83% for MC+; the RL rises by 14% for MC and by 33% for MC+. Because the projected daily P trends are negligible, the sub-daily signal is mainly driven by local temperature. KW - Extreme events KW - Rainfall KW - Climate change KW - Statistical techniques KW - Time series KW - Stochastic models Y1 - 2019 U6 - https://doi.org/10.1175/JCLI-D-19-0136.1 SN - 0894-8755 SN - 1520-0442 VL - 32 IS - 22 SP - 7597 EP - 7609 PB - American Meteorological Soc. CY - Boston ER - TY - CHAP A1 - Bronstert, Axel A1 - Crisologo, Irene A1 - Heistermann, Maik A1 - Öztürk, Ugur A1 - Vogel, Kristin A1 - Wendi, Dadiyorto T1 - Flash-floods: more often, more severe, more damaging? BT - An analysis of hydro-geo-environmental conditions and anthropogenic impacts T2 - Climate change, hazards and adaptation options: handling the impacts of a changing climate N2 - In recent years, urban and rural flash floods in Europe and abroad have gained considerable attention because of their sudden occurrence, severe material damages and even danger to life of inhabitants. This contribution addresses questions about possibly changing environmental conditions which might have altered the occurrence frequencies of such events and their consequences. We analyze the following major fields of environmental changes. Altered high intensity rain storm conditions, as a consequence of regionalwarming; Possibly altered runoff generation conditions in response to high intensity rainfall events; Possibly altered runoff concentration conditions in response to the usage and management of the landscape, such as agricultural, forest practices or rural roads; Effects of engineering measures in the catchment, such as retention basins, check dams, culverts, or river and geomorphological engineering measures. We take the flash-flood in Braunsbach, SW-Germany, as an example, where a particularly concise flash flood event occurred at the end of May 2016. This extreme cascading natural event led to immense damage in this particular village. The event is retrospectively analyzed with regard to meteorology, hydrology, geomorphology and damage to obtain a quantitative assessment of the processes and their development. The results show that it was a very rare rainfall event with extreme intensities, which in combination with catchment properties and altered environmental conditions led to extreme runoff, extreme debris flow and immense damages. Due to the complex and interacting processes, no single flood cause can be identified, since only the interplay of those led to such an event. We have shown that environmental changes are important, but-at least for this case study-even natural weather and hydrologic conditions would still have resulted in an extreme flash flood event. KW - Flash flood KW - Climate change KW - Extreme rainfall KW - Anthropogenic impacts Y1 - 2020 SN - 978-3-030-37425-9 SN - 978-3-030-37424-2 U6 - https://doi.org/10.1007/978-3-030-37425-9_12 SN - 1610-2010 SP - 225 EP - 244 PB - Springer CY - Cham ER - TY - GEN A1 - Vogel, Johannes A1 - Paton, Eva A1 - Aich, Valentin A1 - Bronstert, Axel T1 - Increasing compound warm spells and droughts in the Mediterranean Basin T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - The co-occurrence of warm spells and droughts can lead to detrimental socio-economic and ecological impacts, largely surpassing the impacts of either warm spells or droughts alone. We quantify changes in the number of compound warm spells and droughts from 1979 to 2018 in the Mediterranean Basin using the ERA5 data set. We analyse two types of compound events: 1) warm season compound events, which are extreme in absolute terms in the warm season from May to October and 2) year-round deseasonalised compound events, which are extreme in relative terms respective to the time of the year. The number of compound events increases significantly and especially warm spells are increasing strongly – with an annual growth rates of 3.9 (3.5) % for warm season (deseasonalised) compound events and 4.6 (4.4) % for warm spells –, whereas for droughts the change is more ambiguous depending on the applied definition. Therefore, the rise in the number of compound events is primarily driven by temperature changes and not the lack of precipitation. The months July and August show the highest increases in warm season compound events, whereas the highest increases of deseasonalised compound events occur in spring and early summer. This increase in deseasonalised compound events can potentially have a significant impact on the functioning of Mediterranean ecosystems as this is the peak phase of ecosystem productivity and a vital phenophase. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1127 KW - Compound events KW - Warm spells KW - Droughts KW - Mediterranean basin KW - Extreme events KW - Climate change Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-496294 SN - 1866-8372 IS - 1127 ER - TY - JOUR A1 - Vogel, Johannes A1 - Paton, Eva A1 - Aich, Valentin A1 - Bronstert, Axel T1 - Increasing compound warm spells and droughts in the Mediterranean Basin JF - Weather and climate extremes N2 - The co-occurrence of warm spells and droughts can lead to detrimental socio-economic and ecological impacts, largely surpassing the impacts of either warm spells or droughts alone. We quantify changes in the number of compound warm spells and droughts from 1979 to 2018 in the Mediterranean Basin using the ERA5 data set. We analyse two types of compound events: 1) warm season compound events, which are extreme in absolute terms in the warm season from May to October and 2) year-round deseasonalised compound events, which are extreme in relative terms respective to the time of the year. The number of compound events increases significantly and especially warm spells are increasing strongly – with an annual growth rates of 3.9 (3.5) % for warm season (deseasonalised) compound events and 4.6 (4.4) % for warm spells –, whereas for droughts the change is more ambiguous depending on the applied definition. Therefore, the rise in the number of compound events is primarily driven by temperature changes and not the lack of precipitation. The months July and August show the highest increases in warm season compound events, whereas the highest increases of deseasonalised compound events occur in spring and early summer. This increase in deseasonalised compound events can potentially have a significant impact on the functioning of Mediterranean ecosystems as this is the peak phase of ecosystem productivity and a vital phenophase. KW - Compound events KW - Warm spells KW - Droughts KW - Mediterranean basin KW - Extreme events KW - Climate change Y1 - 2021 U6 - https://doi.org/10.1016/j.wace.2021.100312 SN - 2212-0947 VL - 32 PB - Elsevier CY - Amsterdam ER -