Black Swans in river flood hydrology are unexpected events that surprise flood managers and citizens, causing massive impacts when they do occur, but that appear to be more predictable in retrospect, after their occurrence. My talk aims at showing how black swans in river flood hydrology can "be made grey", i.e. can be anticipated to a certain degree, in probabilistic terms, and/or made less impactful, by (1) expanding information on flood probabilities by gathering data on floods occurred in other places and at other times; (2) understanding the mechanisms causing heavy tails in flood frequency distributions; (3) understanding the mechanisms causing river flood changes in time; (4) accounting for uncertainties in data, models and flood frequency estimates; (5) accounting for the possible dynamics of coupled human-water systems; and (6) coupling the classical top-down approach to hydrological risk assessment based on predictive modelling with a bottom-up approach that is centered on robustness and resilience.

How to cite: Viglione, A.: Extremes in river flood hydrology: making Black Swans grey, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2227, https://doi.org/10.5194/egusphere-egu23-2227, 2023.

Drought-to-flood transitions are both a challenge and opportunity for water management. While the two extremes are often studied separately, their close succession can have severe impacts. The timespan between events can range from rapid transitions happening within a few days to long transitions taking many years. Still, the drivers and frequency of those transitions in specific river basins remain unknown. Therefore, we ask ‘when, where and how often do transitions from streamflow droughts to floods occur?’

To answer these questions, we analyse over 1000 catchments in the contiguous US from the GAGES-II database, identify streamflow droughts and floods, and calculate transition times between both types of extremes. Then, we relate the time and frequency of occurrence and the timespan between extremes to local climate and topographic characteristics. We distinguish between winter and summer transitions to identify hydro-meteorological processes important in different seasons and focus on particularly rapid transitions. 

We find that the duration and frequency of transitions show large spatial variability. Regionally, rapid transitions occur during a typical time of the year which is often related to the presence of snow and melt processes. Snow also dictates seasonal differences in rapid transition frequencies between summer and winter. Snow-free catchments have a lower frequency but higher variability of transitions which makes the phenomenon less predictable. Additionally, reservoirs reduce the occurrence of snow-affected rapid transitions. We conclude that management challenges related to drought-to-flood transitions are particularly pronounced in natural and rainfall-dominated catchments.

How to cite: Götte, J. and Brunner, M.: Drought-to-flood transitions – When and where do they occur?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-666, https://doi.org/10.5194/egusphere-egu23-666, 2023.

Over April 2022, heavy rain in KwaZulu-Natal province in South Africa, followed by intense flooding and mudslides, caused one of the deadliest natural disasters in the country, mostly hard-hitting the areas in and around Durban. The intense rainfall was caused by a cut-of-low mid-latitude depression, known as Storm Issa, which is a common weather system in South Africa, particularly in the spring and summer months. In this study we present an analysis which investigates 1) the reasons why this event has been so impactful in terms of damage and loss compared to other similar events in South Africa and 2) if the intensity and frequency of such a storm is increasing as a result of a changing climate.  The analysis has been carried out at different levels: ERA-5 reanalysis data and rain gauge data have been used to characterize at different temporal and spatial scales the precipitation relative to the event and compared to other similar events; DWS discharge data have been used to analyse the event in terms of hydrological response and flow; and finally the footprint of the event has been reconstructed, following the flow analysis and by means of UNOSAT satellite-detected flood, landslide and damaged structures taken as reference. Among the major outcomes of the analysis we found that the duration and antecedent conditions, most probably also exacerbated by La Nina effect, made the event exceptional, resulting in a flash flood among the highest recorded in the last 70 years. The reconstructed event footprint whilst could be improved in the areas which were mostly affected by landslides, captures well the flooding in the major floodplain.     

How to cite: Scudeler, C., Giani, G., and Tsioulou, A.: The April 2022 South Africa Flood event, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14921, https://doi.org/10.5194/egusphere-egu23-14921, 2023.

Flood disaster resilient design of the bridges is the lifeline of the transport infrastructure. Design of flood disaster resilient bridges is the major requirement for construction of the main highways and railway networks as well as for developing the transport networks in hilly regions and remote areas. Inadequate hydrologic and hydraulic design of the bridges results in failure of the bridges and during the current rainy season, a number of bridges were washed away in the India and other parts of the world, mainly due to it. In the present era, the construction technology is in fairly well advanced state and a major challenge associated in construction of the disaster resilient bridge infrastructure is to estimate the accurate design flood and using it for determination of the highest flood level (HFL) of the bridges incorporating the growing climate-change-induced threats of the intensifying extreme weather events. In this research, a procedure for design flood estimation for the bridges will be developed based on the L-moments approach of flood frequency analysis and its superiority will be demonstrated over the existing procedures. The data will be screened using the discordancy measure (D_i) in terms of the L-moments. Homogeneity of the region will be tested using the L-moments based heterogeneity measure, H. For computing the heterogeneity measure H, 500 simulations will be  performed using the four parameter Kappa distribution. Comparative regional flood frequency analysis studies ill be performed using the L-moments based frequency distributions: viz. Extreme value, General extreme value, Logistic, Generalized logistic, Normal, Generalized normal, Uniform, Pearson Type-III, Exponential, Generalized Pareto, Kappa, and five parameter Wakeby. Based on the L-moment ratio diagram and Z_i^dist -statistic criteria, the robust distribution will be identified and design flood will be estimated using the robust frequency distribution. Effect of climate change will be studied using the CMIP-5 scenarios and the fixed percentage increases in the design flood. The research will create a climate-resilience-centred procedure leading to policy framework comprising of exhaustive methodology, guidelines and tools for design of flood disaster resilient bridges for the road and railway networks to make the transport infrastructure more resilient in the face of future climate change induced uncertainties of the extreme rainfall events.

How to cite: Kumar, R.: Design flood estimation for flood disaster Resilient bridges exposed to climate change, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-882, https://doi.org/10.5194/egusphere-egu23-882, 2023.

The usual goal of palaeoflood hydrology and historical hydrology is, according to the classic concept, to extend the flood records over centuries or millennia back. Many compilations of documentary sources on floods in Western and Central Europe were collected in last two centuries. The palaeoflood records were presented for hundreds of localities in Europe. Numerous individual flood event case studies were carried out and published. On the PAGES Flood Working Group (FWG) website hundreds of flood records are collected in one database. The overall goals of the FWG are "to integrate and analyse existing palaeoflood data at the regional and global scales and to promote and disseminate palaeoflood science and data at different levels". The aim of this contribution is to present the recently created “Map of Extreme Floods” (MEF) ESRI application focused on European floods.  Apart from the FWG goals stated above, the MEF application aims also to the future geographic characterization and mapping of hydrological extreme events. The MEF places some of interpreted documentary sources for Central and Western Europe into relevant spatial and temporal frameworks. Actually, the MEF application more event oriented approach enables to put the fundamental information on European historical floods, i.e. the exact location and datum, into broader spatial and temporal context. The maps created by this tool form the reliable fundament for detailed exploration and including of additional data. The principal MEF application aims are: (i) archiving, (ii) verification, (iii) corrections, (iv) addition of further data and information, (v) exchange of data and last but not least (vi) providing information for both scientists and public. 24 large floods from 1432 to 2002 are now at disposal and next 20 are under preparation. The estimated extremities, economic losses, infrastructural damages, water levels, flood marks etc. are attributed to individual localities. The performance of the MEF application is documented by selected historical extreme flood events, possibly analogical to these recent of 1997, 2002, and 2013.

How to cite: Elleder, L. and Šírová, J.: MEF application- the extreme floods are already in maps!, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3160, https://doi.org/10.5194/egusphere-egu23-3160, 2023.

Extreme wind phenomena generated during convective events are reported every year in France and cause significant material losses. In 2022, several significant events were observed, for example in Normandy in June where a kite surfer lost his life or in August in Corsica where a new wind gust record was recorded (225km/h). However, convective wind gusts are not considered in the design process of residential and industrial infrastructures. Therefore, our study assesses the available databases on convective wind speeds monitored or estimated by MeteoFrance and Keraunos for the period 2000-2019 in order to define a methodology to estimate the wind gusts return level.

Since all these convective events occur during a thunderstorm, the originality of this work was to use lightning data to separate convective from non-convective events. In addition, we considered all available data by projecting them onto the same grid (Meteorage lightning grid with 25 km resolution). A first probability analysis and conditional probabilities knowing the occurrence of a thunderstorm were deduced over the period and by seasons.

Then, we will focus on a very convective region (North-East of France) to evaluate the possibility to estimate the return level of wind gusts with the designed available dataset.

How to cite: Bertrand, N., Gaonac'h, A., Delattre, H., Sabre, M., and Li, L.: Extreme wind gusts assessment in France, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14453, https://doi.org/10.5194/egusphere-egu23-14453, 2023.

An acceleration in the global water cycle with severe rainfall and drought episodes is expected to occur in many regions due to climate change¹. Spatial and temporal disturbances in the atmospheric water budget encompassing changes in precipitation and evaporation rates, soil moisture levels, groundwater recharge and water available for runoff are foreseen, posing great challenges to the global freshwater availability² , food security³ and the sustainability of natural ecosystems⁴ . Thus, the assessment of hydro-meteorological extremes is crucial, particularly in regions such as South America (SA) that are extremely vulnerable to climate change and lack a comprehensive assessment of this extremes. Moreover, SA has two main watersheds (Amazon and La Plata basin) essential for the regional hydroclimate and local and remote precipitation in a global scale, through moisture recycling, transport and convergence.

Regions of Southeast SA, particularly over the La Plata basin and the Pantanal, have witnessed severe drought conditions in recent years. Pronounced soil dryness started to be recorded during mid-2018 over Southeast Brazil, but rapidly spread to areas in Paraguay, Bolivia, and northern Argentina. This abnormal situation lasted until 2021, leading to huge agricultural losses. Extremely low streamflow levels in the Paraná and Paraguay rivers caused serious constraints in the hydropower generation and water supply, and led to disruptions in the waterways that are fundamental for the fluvial transport and economy of these countries. Moreover, the Pantanal biome was also dramatically affected, particularly during 2020, when pronounced soil dry-out conditions concurred with several heatwaves, leading to devastating fires that resulted in catastrophic burned area levels⁷.

This study presents a detailed analysis of the 2019–2021 drought episode over Southeast SA from a climate change and variability context aiming: to (1) evaluate the exceptionality of the soil dry-out conditions within a historical record of 70 years; (2) provide a detailed spatiotemporal evolution (from daily to decadal and regional to large-scale) of soil moisture anomalies across the southeast SA; and (3) assess the large-scale tropical and subtropical atmospheric mechanisms that were responsible for pronounced disturbances in the normal processes of moisture transport and convergence, and that, ultimately, explained the observed soil moisture deficits over southeast SA.

References

• [1] Chagas, V. B. P., Chaffe, P. L. B. & Blöschl, G. Climate and land management accelerate the Brazilian water cycle. Nat. Commun. 13, 5136 (2022).
• [2] Konapala, G., Mishra, A. K., Wada, Y. & Mann, M. E. Climate change will affect global water availability through compounding changes in seasonal precipitation and evaporation. Nat. Commun. 11, 1–10 (2020).
• [3] Lesk, C., Rowhani, P. & Ramankutty, N. Influence of extreme weather disasters on global crop production. Nature 529, 84–87 (2016).
• [4] Seddon, A. W. R., Macias-Fauria, M., Long, P. R., Benz, D. & Willis, K. J. Sensitivity of global terrestrial ecosystems to climate variability. Nature 531, 229–232 (2016).

Acknowledgments:

JG, AR, RT are grateful to Fundação para a Ciência e a Tecnologia for the PhD Grant 2020.05198.BD, I.P./MCTES for the national funding (PIDDAC) – UIDB/50019/2020 and for Dhefeus (2022. 09185.PTDC). RL is grateful to CNPq (Grant 311487/2021-1) and FAPERJ (Grant E26/202.714/2019).

How to cite: Geirinhas, J. L., Russo, A., Libonati, R., Miralles, D. G., Ramos, A. M., and Trigo, R. M.: An insight into the severe 2019-2021 drought over Southeast South America from a daily to decadal and regional to large-scale variability perspective, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-827, https://doi.org/10.5194/egusphere-egu23-827, 2023.

The research aimed at studying the characteristics of hail in the Kvemo Kartli region (Georgia). Hail (30%) is the most frequent natural hydrometeorological event in the territory of Georgia after flash floods (37%). Hail is typical for the Kvemo Kartli region, where agricultural production is the leading industry. It damages farm lands. The study of hail is very important for the development and introduction of hail prevention methods in the region.

We used the observation materials of 7 weather stations of the region for the years of 1961-2022, a catalog was compiled and the following characteristics of hailfall were calculated: probability, number of days, intensity, frequency, duration, and distribution areas.

Hail is observed in the warm spell of the year; especially active processes develop in spring and the first half of summer, which are associated with convective clouds.

The highest number of hailfall days in the region is 12-14 days a year. In the Kvemo Kartli region, hail damage the territory with an area of ​​1 to 5 square kilometers in 38% of its cases; in 33% of cases, it damages an area of ​​less than 1 km². An area of ​​more than 5 km² is damaged in approximately 30% of cases of hail. Rarely, hail damages much larger areas, for example, more than 50 km² is damaged in 3% of cases. The average duration of hailfall is 9-10 minutes. In 60% of cases, hailfall lasts less than 5 minutes, in 80% of cases, the duration of hailfall is less than 10 minutes. In 3% of cases, hail can last for an hour and a half.

Thus, the main climatic characteristics of hail in the Kvemo Kartli region have been identified.

The research results can be used to reduce the negative impact of hail and implement measures to prevent hail.

This work was supported by Shota Rustaveli National Science Foundation of Georgia (SRNSFG) Grant № FR-19-14993.

How to cite: Elizbarashvili, E., Elizbarashvili, M., and Kvirkvelia, B.: Hail in the Kvemo Kartli Region (Georgia), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4255, https://doi.org/10.5194/egusphere-egu23-4255, 2023.

Spain is a territory with spatial variations highly influenced by its distance from the sea and its complex orography, where it is possible to note an uneven distribution of both temperature and precipitation. This study presents an analysis of trends in maximum temperature and precipitation by zone over the period 1951-2021 using monthly data. The database used includes 16156 multivariate time series (maximum temperatures and precipitation) corresponding to different areas of the Spanish territory, distributed over a grid of 5x5km². The methodology used starts by reducing the dimensionality of the time series and with this version are clustered using an approach based on multiscale analysis using a clustering algorithm. In the following, the prototypes of each group are defined, which allows to identify and analyse patterns of change in maximum temperatures and precipitation by zones. An increase in average maximum temperature has been identified in eight zones distributed in Spain from 1951 to 2021. The rate of change of maximum temperature was between 0.060ºC and 0.2155ºC per decade. Areas further south showed a higher rate of increase than areas found in the north. It has been observed that May was the month with the highest variation for all areas in maximum temperature, nevertheless, differences in seasonal variation are evident when passing from one zone to other, as in some there is greater variation in spring months and in others in winter months. An analysis of trends and seasonal variations of precipitation in the identified zones will be carried out and the correlation between patterns of maximum temperature and precipitation will be studied in each of the eight zones.

How to cite: Palacios Gutiérrez, A. and Valencia Delfa, J. L.: Identification of precipitation and maximum temperature patterns in Spain during 1951 to 2021 using clustering based on multiscale analysis of time series, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4466, https://doi.org/10.5194/egusphere-egu23-4466, 2023.

Clay shrink-swell consists in volume changes of clayey, smectite-rich soils as a function of their soil water content. Building foundations can be affected by soil shrinkage during droughts, entailing what is called subsidence damage. This is the second costliest peril covered by the French national natural disaster compensation scheme, the losses amounting to more than 16B€ between 1989 and 2021 (CCR, 2021). As illustrated by the 2022 drought in France, these costs are likely to increase as a result of climate change and of the related amplification of annual soil moisture cycles.

In this context, we investigate the relationship between drought and subsidence damage, using the ISBA land surface model developed by the French meteorological service (Météo-France), geotechnical data from the French geological survey (BRGM) and data from a national claim database operated by the French state-owned national reinsurance company (CCR). We compute several yearly drought indices based on multi-layer soil moisture time series simulated by the ISBA model. Different configurations of the indices are considered, varying in particular the ISBA model settings, and the soil drought definition through a threshold value accounting for a given temporal frequency, for each model soil layer. We assess a large range of configurations by using the Kendall rank correlation of the indices with yearly town-scale insurance claim data from 2000 to 2018, processed using the geotechnical data. The analysis is repeated for five sets of four towns with an important damage history distributed throughout France, in contrasting climate conditions.

Highest rank correlation coefficients are obtained for soil layers deeper than 60 cm, and with temporal frequency threshold values corresponding to intense droughts. Under these conditions, the indices are able to fairly represent the occurrence of damages. The relationship between drought indices and the number of claims is non-linear. This study benefits from the latest improvements in land surface modeling and is a step forwards in climate risk modeling since the indices investigated can be considered as new predictors for subsidence damage. Climate change impact studies will be conducted in a next phase.

[References] CCR: Les Catastrophes naturelles en France, Bilan 1982-2021, 2021.

How to cite: Barthelemy, S., Bernardie, S., Bonan, B., Grandjean, G., Kapsambelis, D., Moncoulon, D., and Calvet, J.-C.: Investigating the relationship between drought and clay-shrinkage-induced subsidence damage at the town scale over France, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6322, https://doi.org/10.5194/egusphere-egu23-6322, 2023.

Since major hail events are quite rare in Germany, there is a lack of information in hail occurrence, size and its spatio-temporal distribution. As hailstorms are often locally very limited events, the hail distribution is hard to analyze precisely. Hail reports can only give a first intuition about the amount of hail overall. There might be a bias in the amount of reports towards too many reports in highly populated areas, which could lead to an underrepresentation of reports in rural and sparsely populated areas. Areal information from weather radar networks can overcome this issue with a high spatio-temporal resolution. As an addition, data from the German Insurance Association (GDV) about damages through hail serve as a very certain source for hail occurrence.

The German radar network consists of 17 dual-polarimetric radar systems, which cover Germany more or less completely. For the analysis of the hail distribution, the Maximum Expected Size of Hail (MESH) and a method based on Vertical Integrated Ice (VII) are used to estimate the hail size. Those sizes are reduced to thresholds to obtain where hail is reasonable or have a significant large size. The results of MESH and VII are finally compared to the eyewitness reports sent to the European Severe Weather Database and the WarnWetter-App. An important comparison are the loss data by the GDV. It can give further insides into the amount and the size of hail.

How to cite: Wilke, T., Schultze, M., and Lengfeld, K.: A first insight into the hail distribution over Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7244, https://doi.org/10.5194/egusphere-egu23-7244, 2023.

Record-breaking heatwaves, both atmospheric or marine, occur regularly throughout the world, leading to a variety of sectoral and societal impacts. According to the WMO, since 1970 there were more than 11 000 reported disasters attributed to these hazards globally, with just over 2 million deaths and US$ 3.64 trillion in losses. Heatwaves are among the top 4 disasters in terms of human losses during the 50-yr long period, with uneven impacts throughout the world.

Madagascar, which is well known for its vast biodiversity, and abundant and unique natural resources, has been affected by successive droughts and hot events with disastrous consequences for the agriculture sector, and consequently increasing food insecurity. During the last decades, climate change and environmental degradation contributed to an escalation of the ecosystem’s fragility, therefore decreasing, even more, food security in subsistence farming regions.

Considering that the association between higher temperatures and water scarcity increases the risk of food insecurity compared to the sole occurrence of individual hazards, it is very important to address extreme events on a compound approach, identifying synergies, driving mechanisms, and dominant atmospheric modes controlling single and combined hazards.

Here the focus is placed on a particularly sensitive region,  the Madagascar Island, which shows significant positive trends in heatwaves metrics over the period 1982–2022 (frequency, intensity, duration, and intensity composite index). The combined occurrence of both marine and atmospheric heatwaves and drought conditions along the Mozambique Channel and Madagascar relying on ERA5 reanalysis was also performed and ranked according to the referred metrics. Of the two zones considered, there is considerable differences between trends when addressing separately the northern and southern regions, particularly in the case of the intensity of marine and atmospheric heatwaves.  

This work was funded by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds (PIDDAC) – UIDB/50019/2020- IDL ,  DHEFEUS - 2022.09185.PTDC and ROADMAP - JPIOCEANS/0001/2019.

How to cite: Russo, A., Santos, R., and Gouveia, C. M.: Compound occurrence of marine and atmospheric heatwaves with drought conditions over the Mozambique Channel and Madagascar Island, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8156, https://doi.org/10.5194/egusphere-egu23-8156, 2023.

When tropical cyclones (TCs) move to the mid-latitudes, they encounter the baroclinic environment where many of them experience extratropical transition (ET) by which they lose the symmetric and warm-core characteristics and transform into extratropical cyclones (ETCs). ETCs are usually faster than TCs and oftentimes destructive to coastal cities with strong wind and heavy precipitation. Climate models predict that the mean intensity of TCs would become stronger fundamentally due to the increase in atmospheric moisture contents in response to global warming. However, whether the destructiveness of ETCs originated from TCs will change in the future has not been explored with a high-resolution fully-coupled model. To understand the future changes in ET events and the destructive potential of these ETCs, we analyzed the high-resolution Community Earth System Model (CESM) simulations (0.25 degrees for the atmosphere and 0.1 degrees for the ocean) with present-day, doubling, and quadrupling CO₂ concentrations.

The high-resolution model well captures the frequency and annual cycle of the ET events compared to observation with underestimated frequency in the North Atlantic and West Pacific while overestimating them in the East Pacific, South Indian, and South Pacific. Our results show that the frequency and ratio of ET events do not change significantly in both CO₂ doubling and quadrupling experiments. An increase in 10-m wind speed at ET completion is observed mainly in North Atlantic and South Indian. We used the total integrated kinetic energy, which depends on the wind speed and the area covered by the high wind region of a storm, to represent the destructive potential of a storm upon ET completion. It is found that the relative ratio of the strongly destructive ETCs to weaker ETCs increase in response to greenhouse warming.

Our study highlights the destructive potential of transitioned TCs. Since ETCs usually have greater spatial coverage than TCs, the former can impact a larger population and region, albeit with lower intensity. Therefore, accurate prediction of future changes in ET events can have significant socio-economic implications.

How to cite: Cheung, H. M. and Chu, J.-E.: Increasing destructive potential of extratropical transition events in response to higher CO2 concentration in global climate model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4736, https://doi.org/10.5194/egusphere-egu23-4736, 2023.

Hydrometeorological extremes (HMEs) pose immense challenges and hazards to communities in a warming world, and this is particularly true for compound extremes (CHMEs) associated with deadly wet and dry events. More attention has been paid to extremes happening in arid and wet regions, nonetheless, temperate regions are understood poorly where more and more HMEs are striking fragile social-ecological systems. Therefore, the study shines a light on a proper temperate region of Europe, Germany. Not only the spatial-temporary variation of individual HMEs (IHMEs) but also compound events are fully investigated over the past seven decades. Notably, we propose a new insight to explore the concurrent extreme wet and dry events (CEDWs). A comprehensive framework is devised here, it combines the percentile and standardized index methods to explore compound extremes first. Different time scales are utilized to identify extreme wet (EWs) and dry events (EDs) separately considering their different evolving processes and impacting patterns on human society. The research presents the spatiotemporal distribution of the number, magnitude, and intensity of IHMEs and CHMEs in the wet and dry regions of Germany. Moreover, the changing tendency and spatial clustering of these events are further discussed by Ordinary Least Squares and Moran Index methods. Our study provides an important perspective on the changes in the spatiotemporal distribution of HMEs in the temperate region, especially the novel discussion of compound events. On the other hand, the research results regarding phases and areas of severe extremes facilitate planners and decision-makers to prioritize disaster management with limited resources and produce effective risk-mitigation plans.

How to cite: Chen, H., Tuo, Y., and Disse, M.: Intensifying Hydrometeorological Extreme Events and Compound Anomalies in a Temperate Region, Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15352, https://doi.org/10.5194/egusphere-egu23-15352, 2023.

The latest projection of temperature under Shared Socioeconomic Pathways (SSPs) scenarios from Coupled Model Intercomparison Project Phase-6 (CMIP6) indicates that, by the 21st century, the global average temperature will increase by over 5.4 °C in the highest-emission scenario and 1.1 °C in the highest mitigation scenario. Climate change is mainly described by changes in two main meteorological variables, i.e., temperature and precipitation. Observed and projected changes in temperature and precipitation significantly influence various hydroclimatic events such as droughts and floods. Therefore, a precise projection of those variables, including at local and regional scales, is crucial and urgently needed. In Poland, the negative impact of the observed warming on the frequency and intensity of droughts and floods has been detected.

In this research, we present a projection of temperature and precipitation variations in Toruń, Poland, for future periods (2015–2100). To accomplish this, several general circulation models (GCMs) are employed under two SSP scenarios, namely SSP1-2.6 and SSP5-8.5 from NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP-CMIP6) datasets. In these models, the historical reference period is 1950–2014, and future projections are for 2015–2100.

The results indicated that the mean annual air temperature will increase from 8.1 °C in the reference period to 8.9 °C in SSP1-2.6 scenario and 10.1 °C in SSP5-8.5 scenario. Precipitation will increase slightly under both scenarios. It is projected that the average annual precipitation in Toruń will change from 514.38 mm in the reference period to 533.15 mm and 522.37 mm during 2015–2100 according to the SSP1-2.6 and SSP5-8.5 scenarios, respectively. It is evident that an increase in precipitation and heavy rainfall will culminate in extreme occurrences such as floods, which will further threaten lives, properties and the environment within the heart of Toruń.

How to cite: Ghazi, B., Przybylak, R., and Pospieszyńska, A.: Impact of climate change on temperature and precipitation in Toruń, Poland, based on CMIP6 under SSP scenarios, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-283, https://doi.org/10.5194/egusphere-egu23-283, 2023.

In 2016, the World Meteorological Organization declared that lightning is an essential climate variable. To date, global change studies have only considered the effect of warming on lightning flash frequency and the global distribution of lightning activity. Furthermore, none of these studies considered the effects of climate change on lightning flash intensity. In our previous studies we suggested based on laboratory experiments that lightning intensity over water surfaces may be influenced by their chemical properties, including salinity (S), pH and total alkalinity (TA). In this study we tested the combined effects of changes in S, TA and pH in Mediterranean Sea surface water on the intensity of laboratory generated electrical sparks, which are considered to be analogous to cloud to sea-surface intensity of lightning discharges. The range of values tested in the lab correspond to changes in S, pH and TA of Mediterranean surface water that were caused by the anthropogenic climate change, ocean acidification and damming of the Nile in the 1960s. Where, the damming of the Nile is generally accepted to have caused nearly 30% of the total salination of Mediterranean surface water until now. The experimental results were used to develop a multivariate linear model of Lightning Flash Intensity (LFI) as a function of S, TA/S, which  and pH. The model was validated with wintertime (DJF) LFI measurements along a Mediterranean Sea zonal profile during the period 2009-2020 compared to corresponding climate model outputs of S, TA and pH. Based on this model, the combined effects of climate change, ocean acidification and the damming of the Nile, may have increased LFI in the Levantine Sea by 16±14% until now relative to the pre-Aswan Dam period. Furthermore, assuming that salinization and acidification of the Levantine Sea will continue at current trends, the LFI is predicted to increase by 25±13% by the year 2050.

How to cite: Asfur, M. and Silverman, J.: Climate mediated changes in seawater chemistry and their potential effects on marine lightning intensity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-334, https://doi.org/10.5194/egusphere-egu23-334, 2023.

How to cite: Chapagain, D., Bharati, L., Mechler, R., Kc, S., Pflug, G., and Borgemeister, C.: Understanding the role of climate change in disaster mortality: Empirical evidence from Nepal, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-647, https://doi.org/10.5194/egusphere-egu23-647, 2023.