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Georgia Lazoglou     Other 
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Georgia Lazoglou published an article in November 2018.
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CONFERENCE-ARTICLE 8 Reads 0 Citations <strong>Evaluation of extreme dry and wet conditions using climate and hydrological indices in the upper part of the Gal... Christos Mattas, Christina Anagnostopoulou, Panagiota Venets... Published: 15 November 2018
Proceedings of 3rd International Electronic Conference on Water Sciences (ECWS-3), doi: 10.3390/ECWS-3-05823
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Climate changes in the Mediterranean region especially those related to changes in rainfall distribution and occurrence of extreme events affect local economies. Agriculture is a sector strongly affected by climate conditions and concerns the majority of the Greek territory. The Gallikos river basin is an area of great interest regarding climate change impacts since it is an agricultural area depended on surface water resources and an area in which extreme events relatively often take place (e.g. floods). Long time series precipitation (27 years) and temperature data derived from measurement stations along with reanalysis data (ERA INTERIM) were used for the estimation of water availability and climate type over time in the area. The Standardized Precipitation Index and De Martonne aridity index was employed. The water flow measurements were correlated in order to investigate the interrelation between the different river branches and the extent of the meteorological changes effect in the basin. Descriptive statistics and cumulative curves were applied to check homogeneity of data. The results revealed that the climate type varies from semi arid to very wet and water availability ranges from moderately dry to extremely wet years. Reanalysis data overestimate precipitation. The meteorological changes affect at the same time the entire basin since the flow rate peaks occur simultaneously in the hydrographic network at different areas.

CONFERENCE-ARTICLE 12 Reads 0 Citations Copula bias correction for extreme precipitation in re-analysis data over a Greek catchment Georgia Lazoglou, Christina Anagnostopoulou, Charalampos Sko... Published: 15 November 2018
Proceedings of 3rd International Electronic Conference on Water Sciences (ECWS-3), doi: 10.3390/ECWS-3-05817
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The projection of extreme precipitation events with higher accuracy and reliability, which engender severe socioeconomic impacts more frequently, is considered a priority research topic in the scientific community. Although large scale initiatives for monitoring meteorological and hydrological variables exist, the lack of data is still evident particularly in regions with complex topographic characteristics. The latter results in the use of reanalysis data or data derived from Regional Climate Models, however both datasets are biased to the observations resulting in non-accurate results in hydrological studies. The current research presents a newly developed statistical method for the bias correction of the maximum rainfall amount at watershed scale. In particular, the proposed approach necessitates the coupling of a spatial distribution method, namely Thiessen polygons, with a multivariate probabilistic distribution method, namely copulas, for the bias correction of the maximum precipitation. The case study area is the Nestos river basin where the several extreme episodes that have been recorded have direct impacts to the regional agricultural economy. Thus, using daily data by three monitoring stations and daily reanalysis precipitation values from the grids closest to these stations, the results demonstrated that the bias corrected maximum precipitation totals (greater than 90%) is much closer to the real max precipitation totals, while the respective reanalysis value underestimates the real precipitation totals. The overall improvement of the outputs, shows that the proposed Thiessen-copula method could constitute a significant asset to hydrologic simulations.

Article 2 Reads 0 Citations A review of statistical methods to analyze extreme precipitation and temperature events in the Mediterranean region Georgia Lazoglou, Christina Anagnostopoulou, Konstantia Toli... Published: 14 April 2018
Theoretical and Applied Climatology, doi: 10.1007/s00704-018-2467-8
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Article 0 Reads 0 Citations Joint distribution of temperature and precipitation in the Mediterranean, using the Copula method Georgia Lazoglou, Christina Anagnostopoulou Published: 12 March 2018
Theoretical and Applied Climatology, doi: 10.1007/s00704-018-2447-z
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Article 0 Reads 0 Citations The Exceptionally Cold January of 2017 over the Balkan Peninsula: A Climatological and Synoptic Analysis Christina Anagnostopoulou, Konstantia Tolika, Georgia Lazogl... Published: 15 December 2017
Atmosphere, doi: 10.3390/atmos8120252
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An exceptionally cold episode occurred in January 2017 over the Balkan Peninsula. Analysis of historical records showed that it was one of the coldest extreme episodes. Even though the low temperatures of January 2017 did not break previous low records for all stations, the long duration was quite extreme, resulting in strong socioeconomic impacts in the region of interest. The 10-year to 100-year return values of minimum temperatures were calculated based on block maxima method and the maximum likelihood estimates. The estimated return periods of the absolute minimum temperature are approximately 15 or 20 years for almost all stations. For only one station, the absolute minimum temperature of January 2017 might happen once in every 300 years according to the return level results. Moreover, the extreme cold episode over the Balkans during the period of 5 January 2017 to 12 January 2017 was associated with a significant outbreak of arctic air masses into eastern–central Europe and the Balkans and a cutoff low at the level of 500 hPa over the region.
CONFERENCE-ARTICLE 5 Reads 1 Citation <strong>An overview of statistical methods for studying the extreme rainfalls in Mediterranean.</strong> Georgia Lazoglou, Christina Anagnostopoulou Published: 17 July 2017
Proceedings, doi: 10.3390/ecas2017-04132
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Extreme rainfall is one of the most devastating natural events. The frequency and intensity of these events has increased. This trend will likely continue as the effects of climate change become more pronounced. As a consequence, it is necessary to evaluate the different statistical methods that assess the occurrence of the extreme rainfalls. This research evaluates some of the most important statistical methods that are used for the analysis of the extreme precipitation events. Extreme Value Theory is applied on ten station data located in the Mediterranean region. Furthermore, its two main fundamental approaches (Block-Maxima and POT) and three commonly used methods for the calculation of the extreme distributions parameters (Maximum Likelihood, L-Moments, and Bayesian) are analyzed and compared. The results showed that the Generalized Pareto Distribution provides better theoretical justification to predict extreme precipitation compared to Generalized Extreme Value (GEV) distribution while in the majority of stations the most accurate parameters for the highest precipitation levels are estimated with the Bayesian method. Extreme precipitation for return period of 50, 150 and 300 years were finally obtained which indicated that Generalized Extreme Value Distribution with Bayesian estimator presents the highest return levels for western stations, while for the eastern Mediterranean stations the Generalized Pareto Distribution with Bayesian estimator presents the highest ones.