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Μη διαθέσιμη περίληψη Not available summarization Presented on: Journal of Hydrometeorology

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Summarization: The characteristics of the cyclone tracks that caused precipitation events of variable intensity for the period 1979–2011 over the island of Crete are presented. The data set used for cyclone identification is the 0.5◦ × 0.5◦ , 30 years European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim mean sea-level pressure. Cyclone characteristics are calculated with the aid of the Melbourne University algorithm (MS scheme). Daily precipitation data from a dense gauging network over the island of Crete are also used for the classification of the precipitation events in terms of rain accumulation (intensity). Daily precipitation is classified in three categories and the associated cyclones are chosen according to their distance from Crete island. The seasonal and annual cycle of the physical characteristics of the cyclone tracks are investigated with respect to the cyclones’ relative position to the island of Crete. It was found that cyclones affecting Crete most frequently approach from the western side of the island and the actual cyclone centers associated with precipitation events are usually located northwest and southeast of the Crete domain. Cycloneinduced rainfall increases in function to cyclones’ depth, radius and propagation velocity increase as well as cyclones’ pressure decrease. Spring cyclones that affect Crete with rainfall present lower pressures and higher cyclone propagation velocity in contrast to the ones associated with winter and autumn precipitation events. The examination of the relation between cyclone characteristics and precipitation occurrence provides valuable information related to forecasting potential and management of the water resources and the rainfall extremes. Presented on: Natural Hazards and Earth System Sciences

Summarization: Soil temperature is a key factor of plant growth and biological enzyme activities occurring in the soil, affected by the land cover, the evapotranspiration rate, the albedo, and the energy budget of the soil surface. In recent decades, efforts have been made to conserve soils against nonsustainable anthropogenic pressures. Changes in climate can impose additional threats on soil sustainability, as global scale soil temperature regime alterations are expected under global warming. Here, data from three well-established global climate models, spanning from 1981 to as far as 2120, are used to force the JULES (Joint UK Land Environment Simulator) model and produce simulations of soil temperature, calculating the water and energy budgets of the land surface. Modeled soil temperature data are used to estimate the climate-induced changes in the global soil temperature regimes at three different global warming levels. The results show significant shifts in the soil temperature regime for extended areas of the world, especially in the northern hemisphere. Pergelic and Cryic areas are reduced, whereas the Mesic and Thermic soils gain large areas in all three studied scenarios. Implications of the warming patterns might indicate the northward shift of various croplands in regions that until now their cultivation was not possible. Presented on: Soil Science

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Summarization: Soil salinisation is one of the major soil degradation threats occurring in Europe. The effects of salinisation can be observed in numerous vital ecological and non-ecological soil functions. Drivers of salinisation can be detected both in the natural and man-made environment, with climate and the foreseen climate change also playing an important role. This review outlines the state of the art concerning drivers and pressures, key indicators as well as monitoring, modeling and mapping methods for soil salinity. Furthermore, an overview of the effect of salinisation on soil functions and the respective mechanism is presented. Finally, the state of salinisation in Europe is presented according to the most recent literature and a synthesis of consistent datasets. We conclude that future research in the field of soil salinisation should be focused on among others carbon dynamics of saline soil, further exploration of remote sensing of soil properties and the harmonization and enrichment of soil salinity maps across Europe within a general context of a soil threat monitoring system to support policies and strategies for the protection of European soils. Presented on: Science of the Total Environment

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Summarization: The present paper summarizes the advances of flash flood research for the Greek case study, within the frame of HYDRATE EC funded project. As a first step, a collation of homogenous primary data on flash floods occurred in Greece based on various data sources resulted in 21 documented events, enriching the HYDRATE database. Specific major events were selected for further detailed data collation and analysis. A common intensive post event field survey was conducted by various researchers with different skills and experience, in order to document the 18th of September 2007, Western Slovenia flash flood event. The observation strategy and the lessons learned during this campaign were applied successfully for surveying an event in Crete. Two flash flood events occurred in Crete were selected for detailed analysis, the 13th of January 1994 event occurred in Giofiros basin and the 17th of October 2006 event occurred in Almirida basin. Several techniques, like distributed rainfall-runoff modelling, hydraulic modelling, indirect and empirical peak discharge estimation, were applied for the understanding of the dominant flash flood processes and the effect of initial conditions on peak discharge. In a more general framework, the seasonality of the hydrometeorologic characteristics of floods that occurred in Crete during the period 1990-2007 and the atmospheric circulation conditions during the flood events were examined. During the three and a half years research period, many lessons have learnt from a fruitful collaboration among the project partners. HYDRATE project improved the scientific basis of flash flood research and provided research knowledge on flood risk management. Presented on

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Μη διαθέσιμη περίληψη Not available summarization Παρουσιάστηκε στο: 1st International Symposium of the Faculty of Mines (ITU) on Earth Sciences and Engineering

Summarization: This report is an output from Work Block 4 Extremes: frequency, severity and scale, and contributes to Task 4.1.1 Investigate processes controlling the propagation of drought. WATCH deliverables D 4.1.4 Report on the increased understanding of the propagation of drought in different hydro-climatological regions, physical catchment structures and different scales, D 4.1.5 Generic method to quantify the propagation of a drought and contributes to M4.1-7 Analysis of major historical extreme events with metamodel. Edition: 32 Part of series

Summarization: Cyclones passing over Crete originate mainly from southwest, west and northwest directions and are of varying size and intensity. A number of these cyclones cause flash floods. In this study, an attempt was made to associate the synoptic scale atmospheric circulation patterns prevailing over the eastern Mediterranean region with flood occurrences in Crete during the period 1991 to 2009. The atmospheric circulation conditions during the flood events were examined based on ERA Interim reanalysis datasets with resolution T255 for spectral field (or about 79km x79km) available from ECMWF. The atmospheric circulation was classified in 6 synoptic types, according to the wind flow and geopotential or pressure pattern at 500 hPa and surface, respectively. The Melbourne University Cyclone Tracking Algorithm was employed to examine the genesis, tracks and depth of these cyclones. It was found that in the vast majority of the flood events the respective cyclones develop over the Adriatic and Ionian seas and then affect the western part of Crete. The cyclones are mainly attributed to the category CLOSE, revealing characteristics of vertically organized baroclinic systems. The cyclones appear their maximum intensity before they affect Crete, mainly over western Mediterranean, implying the synergy of topographical factors. They are mainly characterized by long duration and track length. Παρουσιάστηκε στο: Protection and restoration of the environment XI

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Μη διαθέσιμη περίληψη Not available summarization Παρουσιάστηκε στο: Περιοδικό Διάσταση ΤΕΕ Δυτικής Κρήτης

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Μη διαθέσιμη περίληψη Not available summarization Presented on: Journal of Hydrology

Μη διαθέσιμη περίληψη Not available summarization Παρουσιάστηκε στο: EGU2013- 4410

Summarization: The relationship of lightning activity and rainfall is investigated for rain events of variable intensity. Rain data from 22 gauging stations over the island of Crete and lightning activity from the Global Lightning Network including both cloud-to-ground and some cloud flashes are analyzed for the period September 2012 to June 2014. Local thunderstorms' characteristics are investigated both individually as well as in groups according to the results of k-means clustering algorithm in 3 dimensions (space (x, y) and time (t)) in which the number of clusters is decided by G-means algorithm. Correlation of non-zero pairs of rain intensity and number of flashes is examined at various time intervals, time lags and effective radii. Also, correlation of flash count within 50 km radius around the stations is examined for the rain events of maximum hourly intensity for each gauging station. The highest coincidence of lightning clusters with intense rain events reaches 60% when gauges are 25-30 km from the cluster center. Maximum correlation within non-zero pairs of rain intensity and flashes number is obtained for more intense rain (99th percentile) and for increased flash count within the searching area (more than 10 flashes). Also, correlation is stronger for shorter time windows. The findings of this study improve the understanding of thunderstorm events and could provide staple information for the improvement of forecasting extreme events. Presented on: Atmospheric Research

Summarization: Precipitation is the most important and well studied hydro-meteorological variable and its characteristics and variability have challenged various scientific fields like water resources management and climate change. As a hydrological model input, precipitation is a space and time dependent variable with an uncertainty introduced due to instrument or measurement errors. This paper presents an uncertainty assessment of precipitation time series using the Data Uncertainty Engine (DUE), a tool developed within the framework of the EC-funded project HarmoniRiB (Harmonised Techniques and Representative River Basin Data for Assessment and Use of Uncertainty Information in Integrated Water Management). The precipitation series are from the Geropotamou Watershed, Crete, Greece. The results of this study will help identify the uncertainty in the precipitation measurements and will provide decision makers with more reliable information from both raw data and models. Presented on

Global water models (GWMs) simulate the terrestrial water cycle, on the global scale, and are used to assess the impacts of climate change on freshwater systems. GWMs are developed within different modeling frameworks and consider different underlying hydrological processes, leading to varied model structures. Furthermore, the equations used to describe various processes take different forms and are generally accessible only from within the individual model codes. These factors have hindered a holistic and detailed understanding of how different models operate, yet such an understanding is crucial for explaining the results of model evaluation studies, understanding inter-model differences in their simulations, and identifying areas for future model development. This study provides a comprehensive overview of how state-of-the-art GWMs are designed. We analyze water storage compartments, water flows, and human water use sectors included in 16 GWMs that provide simulations for the Inter-Sectoral Impact Model Intercomparison Project phase 2b (ISIMIP2b). We develop a standard writing style for the model equations to further enhance model improvement, intercomparison, and communication. In this study, WaterGAP2 used the highest number of water storage compartments, 11, and CWatM used 10 compartments. Seven models used six compartments, while three models (JULES-W1, Mac-PDM.20, and VIC) used the lowest number, three compartments. WaterGAP2 simulates five human water use sectors, while four models (CLM4.5, CLM5.0, LPJmL, and MPI-HM) simulate only water used by humans for the irrigation sector. We conclude that even though hydrologic processes are often based on similar equations, in the end, these equations have been adjusted or have used different values for specific parameters or specific variables. Our results highlight that the predictive uncertainty of GWMs can be reduced through improvements of the existing hydrologic processes, implementation of new processes in the models, and high-quality input data.

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Summarization: Climate models project a much more substantial warming than the 2ĝ€°C target under the more probable emission scenarios, making higher-end scenarios increasingly plausible. Freshwater availability under such conditions is a key issue of concern. In this study, an ensemble of Euro-CORDEX projections under RCP8.5 is used to assess the mean and low hydrological states under +4 °C of global warming for the European region. Five major European catchments were analysed in terms of future drought climatology and the impact of +2 °C versus +4 °C global warming was investigated. The effect of bias correction of the climate model outputs and the observations used for this adjustment was also quantified. Projections indicate an intensification of the water cycle at higher levels of warming. Even for areas where the average state may not considerably be affected, low flows are expected to reduce, leading to changes in the number of dry days and thus drought climatology. The identified increasing or decreasing runoff trends are substantially intensified when moving from the +2 to the +4° of global warming. Bias correction resulted in an improved representation of the historical hydrology. It is also found that the selection of the observational data set for the application of the bias correction has an impact on the projected signal that could be of the same order of magnitude to the selection of the Global Climate Model (GCM). Presented on: Hydrology and Earth System Sciences

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Summarization: A robust signal of a warmer and drier climate over the western Mediterranean region is projected from the majority of climate models. This effect appears more pronounced during warm periods, when the seasonal decrease of precipitation can exceed control climatology by 25-30%. The rapid development of Crete in the last 30 years has exerted strong pressures on the natural resources of the region. Urbanization and growth of agriculture, tourism and industry had strong impact on the water resources of island by substantially increasing water demand. The objective of this study is to analyze and assess the impact of global change on the water resources status for the island of Crete for a range of 24 different scenarios of projected hydro-climatological regime, demand and supply potential. Water resources application issues analyzed and facilitated within this study, focusing on a refinement of the future water demands of the island, and comparing with "state of the art" global climate model (GCM) results and an ensemble of regional climate models (RCMs) under three different emission scenarios, to estimate water resources availability, during the 21st century. A robust signal of water scarcity is projected for all the combinations of emission (A2, A1B and B1), demand and infrastructure scenarios. Despite the uncertainty of the assessments, the quantitative impact of the projected changes on water availability indicates that climate change plays an equally important role to water use and management in controlling future water status in a Mediterranean island like the island of Crete. The outcome of this analysis will assist in short and long-term strategic water resources planning by prioritizing water related infrastructure development. Presented on

Summarization: Climate and weather patterns are an essential resource for outdoor tourism activities. The projected changes in climate and weather patterns are expected to affect the future state of tourism. The present study aims to quantify the positive or negative effect of a 2 °C global warming on summertime climate comfort in the sense of exercising activities that involve light body activity. The well-established Climate Index for Tourism (CIT) and three variants of the widely used Tourism Climatic Index (TCI) were analyzed. Additionally, a new index based on TCI and CIT was tested and compared against the precious indices. Past and future climate data of five high-resolution regional climate models (RCMs) from different Representative Concentration Pathways (RCP4.5 and RCP8.5) of the European Coordinated Regional Climate Downscaling Experiment (Euro-CORDEX) for a +2 °C period were used. The results indicate improvement in the climate comfort for the majority of European areas for the May to October period. For the June to August period, central and northern European areas are projected to improve, while marginal improvement is found for Mediterranean countries. Furthermore, in specific cases of adjacent Mediterranean areas such as the southern Iberian Peninsula, the June to August climate favorability is projected to reduce as a result of the increase to daytime temperature. The use of a set of different indices and different RCMs and RCPs samples a large fraction of the uncertainty that is crucial for providing robust regional impact information due to climate change. The analysis revealed the similarities and the differences in the magnitude of change across the different indices. Moreover, discrepancies were found in the results of different concentration pathways to the +2 °C global warming, with the RCP8.5 projecting more significant changes for some of the analyzed indices. The estimation of the TCI using different timescale climate data did not change the results on tourism significantly. Presented on: International Journal of Biometeorology

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Μη διαθέσιμη περίληψη Not available summarization Παρουσιάστηκε στο: 9th Internationl Conference on Environmental Science and Technology

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Summarization: Ensemble pan-European projections under a 2. °C global warming relative to the preindustrial period reveal a more intense warming in south Eastern Europe by up to +3. °C, thus indicating that impacts of climate change will be disproportionately high for certain regions. The Mediterranean is projected as one of the most vulnerable areas to climatic and anthropogenic changes with decreasing rainfall trends and a continuous gradual warming causing a progressive decline of average stream flow. Many Mediterranean regions are currently experiencing high to severe water stress induced by human and climate drivers. Changes in average climate conditions will increase this stress notably because of a 10-30% decline in freshwater resources. For small island states, where accessibility to freshwater resources is limited the impact will be more pronounced. Here we use a generalized cross-sectoral framework to assess the impact of climatic and socioeconomic futures on the water resources of an Eastern Mediterranean island. A set of representative regional climate models simulations from the EURO-CORDEX initiative driven by different RCP2.6, RCP4.5, and RCP8.5 GCMs are used to form a comparable set of results and a useful basis for the assessment of uncertainties related to impacts of 2° warming and above. A generalized framework of a cross-sectoral water resources analysis was developed in collaboration with the local water authority exploring and costing adaptation measures associated with a set of socioeconomic pathways (SSPs). Transient hydrological modeling was performed to describe the projected hydro-climatological regime and water availability for each warming level. The robust signal of less precipitation and higher temperatures that is projected by climate simulations results to a severe decrease of local water resources which can be mitigated by a number of actions. Awareness of the practical implications of plausible hydro-climatic and socio-economic scenarios in the not so distant future may be the key to shift perception and preference towards a more sustainable direction. Presented on: Journal of Hydrology

Summarization: Global climate model (GCM) outputs feature systematic biases that render them unsuitable for direct use by impact models, especially for hydrological studies. To deal with this issue, many bias correction techniques have been developed to adjust the modelled variables against observations, focusing mainly on precipitation and temperature. However, most state-of-the-art hydrological models require more forcing variables, in addition to precipitation and temperature, such as radiation, humidity, air pressure, and wind speed. The biases in these additional variables can hinder hydrological simulations, but the effect of the bias of each variable is unexplored. Here we examine the effect of GCM biases on historical runoff simulations for each forcing variable individually, using the JULES land surface model set up at the global scale. Based on the quantified effect, we assess which variables should be included in bias correction procedures. To this end, a partial correction bias assessment experiment is conducted, to test the effect of the biases of six climate variables from a set of three GCMs. The effect of the bias of each climate variable individually is quantified by comparing the changes in simulated runoff that correspond to the bias of each tested variable. A methodology for the classification of the effect of biases in four effect categories (ECs), based on the magnitude and sensitivity of runoff changes, is developed and applied. Our results show that, while globally the largest changes in modelled runoff are caused by precipitation and temperature biases, there are regions where runoff is substantially affected by and/or more sensitive to radiation and humidity. Global maps of bias ECs reveal the regions mostly affected by the bias of each variable. Based on our findings, for global-scale applications, bias correction of radiation and humidity, in addition to that of precipitation and temperature, is advised. Finer spatial-scale information is also provided, to suggest bias correction of variables beyond precipitation and temperature for regional studies. Παρουσιάστηκε στο: Hydrology and Earth System Sciences

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Summarization: An improved bias correction method for daily GCM precipitation is presented. The method belongs to the widely used family of transfer function correction methods. The method utilizes multiple segments of the cumulative density function (CDF) to fit each a theoretical distribution, instead of the commonly used single transfer function on the entire spectrum of the CDF. The optimum number of segments that covers the CDF space is obtained resulting in a better fit between the bias corrected GCM and the observed precipitation data. The global precipitation data used was from the Institut Pierre-Simon Laplace Coupled Model (IPSL) for the period 1960-2100 and are bias corrected using the precipitation observations of Watch Forcing Data (WFD), a dataset of observed values created in the frame of the Water and Global Change EU project. The accuracy of the method was then assessed between the bias-corrected IPSL data and (WFD). Results show an improvement in the mean precipitation over the past period of 1960-2000 comparing to the newly available corrected IPSL global precipitation data of WATCH. Similarly the new method performs better for the representation of the precipitation extremes, defined as the mean precipitation exceeding the 99.9th percentile. The method is applied in the future precipitation for the periods 2010-2050 and 2060-2100. Results show increase in the mean global precipitation in both periods under A2 and B1 emission scenarios, confirming the intensification of the water cycle. Presented on

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Summarization: Bias correction of climate variables is a standard practice in climate change impact (CCI) studies. Various methodologies have been developed within the framework of quantile mapping. However, it is well known that quantile mapping may significantly modify the long-term statistics due to the time dependency of the temperature bias. Here, a method to overcome this issue without compromising the day-to-day correction statistics is presented. The methodology separates the modeled temperature signal into a normalized and a residual component relative to the modeled reference period climatology, in order to adjust the biases only for the former and preserve the signal of the later. The results show that this method allows for the preservation of the originally modeled long-term signal in the mean, the standard deviation and higher and lower percentiles of temperature. To illustrate the improvements, the methodology is tested on daily time series obtained from five Euro CORDEX regional climate models (RCMs). Presented on: Earth System Dynamics