The eastern Mediterranean teleconnection pattern: the structure, the dynamic processes and the impact on regional climate

The objective of this thesis is: a) the identification of teleconnection patterns located in eastern mediterranean region, b) the study of the structure and characteristics of the eastern mediterranean teleconnection pattern (emp), c) the investigation and understanding of dynamic and thermodynamic processes that contribute to the formation of emp, d) its impact on the regional climate of the mediterranean and e) the investigation of possible future variations of emp under global warming conditions. The atmospheric teleconnection patterns appear as preferred modes of low-frequency natural variability of the atmospheric circulation with fixed oscillating nodes and antinodes, called poles. The existence of teleconnection patterns located eastern mediterranean investigated analyzing climate data of northern hemisphere geopotential heights for the period 1958-2003 with the aid of correlation analysis and principal component analysis, identifying a teleconnection pattern with two poles centered in eastern mediterranean and northeastern atlantic in geopotential height fields of 300 and 500hpa and maximum intensity during winter. This pattern is called the eastern mediterranean teleconnection pattern (emp) and a positive and a negative phase are discriminated. Furthermore, the mechanisms that are suggested to dominate on the formation of teleconnections were investigated: a) in planetary scale the rossby wave propagation, b) in synoptic scale, the impact of transient eddies in the mean flow and c) the troposphere-stratosphere interaction through the intrusion of stratospheric air masses into the troposphere. In order to investigate the impact of the emp on mean distributions of temperature and precipitation, as well as on their extreme events in eastern mediterranean, the regularized canonical correlation analysis (rcca) and the composite analysis for both phases were applied. It was found that the two phases of emp affect oppositely the eastern mediterranean climate. Finally, the possible variations of the position and the intensity of emp in the future, as the knowledge of the teleconnection behavior can help in the improvement of climate models simulations, as well as the resulting impacts on the future regional climate of eastern mediterranean were investigated.Αντικείμενο της διατριβής είναι α) ο εντοπισμός τηλεσυνδέσεων της ατμοσφαιρικής κυκλοφορίας στην περιοχή της ανατολικής μεσογείου, β) η μελέτη της δομής και των χαρακτηριστικών της τηλεσύνδεσης της ανατολικής μεσογείου (eastern mediterranean teleconnection pattern-εμρ) γ) η διερεύνηση και ερμηνεία των δυναμικών και θερμοδυναμικών διεργασιών που συμβάλλουν στη δημιουργία της, δ) η επίδρασή της στο περιοχικό κλίμα της μεσογείου και ε) η διερεύνηση των μεταβολών της στο μέλλον υπό συνθήκες παγκόσμιας θέρμανσης. Οι ατμοσφαιρικές τηλεσυνδέσεις εμφανίζονται κυρίως σαν προτιμώμενες καταστάσεις της φυσικής μεταβλητότητας της ατμοσφαιρικής κυκλοφορίας χαμηλής συχνότητας. Η μελέτη της ύπαρξης τηλεσυνδέσεων με κέντρο την ανατολική μεσόγειο, πραγματοποιήθηκε μέσω της ανάλυσης κλιματολογικών δεδομένων γεωδυναμικού του βορείου ημισφαιρίου για την περίοδο 1958-2003 με τη βοήθεια της ανάλυσης συσχετίσεων (correlation analysis) και της ανάλυσης σε κύριες συνιστώσες (principal component analysis) που οδήγησε στη διαπίστωση της ύπαρξης μίας τηλεσύνδεσης με πόλους στην ανατολική μεσόγειο και το βορειοανατολικό ατλαντικό, στο πεδίο των γεωδυναμικών υψών για τις επιφάνειες των 300 και 500 hpa και με μέγιστη ένταση κατά το χειμώνα. Η τηλεσύνδεση αυτή ονομάστηκε eastern mediterranean teleconnection pattern (emp) και διακρίνεται σε δύο φάσεις, τη θετική και την αρνητική. Μελετήθηκαν οι μηχανισμοί που θεωρητικά έχουν προταθεί ότι μπορούν να οδηγήσουν στο σχηματισμό των τηλεσυνδέσεων: α) σε πλανητική κλίμακα η διάδοση των κυμάτων rossby, β) σε συνοπτική κλίμακα η επίδραση των transients eddies στην πλανητική ροή και γ) η αλληλεπίδραση στρατόσφαιρας-τροπόσφαιρας μέσω εισβολής στρατοσφαιρικού αέρα στην τροπόσφαιρα. Για τη μελέτη της επίδρασης της εmp στη μέση κατανομή της θερμοκρασίας, της βροχόπτωσης και των αντίστοιχων ακραίων φαινομένων στην ανατολική μεσόγειο, εφαρμόστηκε η κανονικοποιημένη ανάλυση κανονικών συσχετίσεων (rcca) και η ανάλυση σύνθετων ανωμαλιών των παραμέτρων για τις δύο φάσεις. Βρέθηκε ότι η emp επηρεάζει το κλίμα της ανατολικής μεσογείου με αντίθετο τρόπο σε κάθε φάση. Τέλος, έγινε διερεύνηση της τυχόν μεταβολής της θέσης και της έντασης της emp στο μέλλον, καθώς η γνώση της συμπεριφοράς των τηλεσυνδέσεων στο μελλοντικό κλίμα μπορεί να οδηγήσει στη βελτίωση των προσομοιώσεων των κλιματικών μοντέλων και .διερευνήθηκαν οι επακόλουθες επιπτώσεις στο μελλοντικό περιοχικό κλίμα της ανατολικής μεσογείου, με δεδομένα προσομοιώσεων κλιματικών μοντέλων

A Statistical Investigation of the Impact of the Indian Monsoon on the Eastern Mediterranean Circulation

The Indian summer monsoon (ISM) is a prominent feature of the summer circulation in the Northern Hemisphere (NH) and has been found to modulate the weather and climate conditions in many remote regions. This study investigates the most recurrent patterns of summertime midlatitude circulation, over the eastern Mediterranean (EM) and also globally, that are most associated with the ISM. Monthly data of 44 summers from the ERA40 dataset are used and two multidimensional statistical methods, the Principal Component Analysis (PCA) and Canonical Correlation Analysis (CCA), are implemented. The ISM is found to be related to subsidence anomalies in the middle and more extendedly in the upper troposphere over the central and eastern Mediterranean and with an Etesian-like pattern regarding the field of the lower troposphere winds. An equatorial Rossby wave pattern, extending westward from an ISM heat source up to EM and N. Africa, was identified to be associated with the variability of ISM. The observed relationship between the ISM and the EM circulation features can be attributed to this equatorial Rossby wave response to the monsoon forcing. CCA implementation revealed the interconnection of the aforementioned PCA results with an ISM action center over the northern Arabian Sea and the monsoon trough region

An Insight into the Factors Controlling Delta Flood Events: The Case of the Evros River Deltaic Plain (NE Aegean Sea)

The present contribution aims to give an insight into the main terrestrial and marine processes leading to delta flooding in the case of the transboundary Evros delta, located at the microtidal NE Aegean Sea, on the basis of recorded flood events in the Evros deltaic plain. The prevailing weather conditions at the onset of the event, along with sea-level rise above the mean state, portray the mechanism for the development of compound flood events and subsequent riparian flooding. This system blocks the riverine water’s seaward exit, resulting in the flooding of the lower deltaic plain. The river discharge is recognized as a secondary factor acting mainly toward the persistence of the events. Several limitations restrict the quantification potential of the relative contribution of the key factors to the development, onset, and duration of a flood. Mitigation of the impacts of such flood events requires intercountry cooperation and a management plan based on a network of environmental monitoring

Evaluation of different laboratory tests for the detection of metallo-beta-lactamase production in Enterobacteriaceae

Objectives: Clinical isolates of Klebsiella pneumoniae (91), Escherichia coli (49), Enterobacter spp. (27), Proteus mirabilis (17), Citrobacter freundii (2), Providencia stuartii (3) and Serratia spp. (5), with various MICs of imipenem, were examined for production of metallo-beta-lactamases (MBLs) with different phenotypic laboratory tests that have been previously published to detect MBLs in Pseudomonas aeruginosa and Acinetobacter spp. Methods: A total of 194 (95 MBL-positive and 99 MBL-negative) clinical isolates with imipenem MICs <= 0.25 to > 256 mg/L were examined. All isolates were evaluated by the double-disc synergy test (DDST), the combination disc test (CDT), the MBL Etest and the modified Hodge test. The presence of bla(VIM) and bla(IMP) genes was evaluated by in situ hybridization with specific probes and was certified by PCR. Results: In 30 bla(VIM)-positive isolates that exhibited MICs of imipenem <= 4 mg/L, MBL Etest could not be evaluated. CDT with ceftazidime and 1900 or 750 mu g of EDTA, and DDST after applying an imipenem disc 10 mm apart from a disc containing similar to 1900 mu g of EDTA, showed the highest sensitivity (97.9% to 100%) and specificity (87.9% to 96%) rates among the analysed procedures. CDT with imipenem and 1900 mu g of EDTA exhibited a sensitivity of 94.7% and showed very good specificity (98%). Conclusions: The CDT with imipenem/imipenem+0.5 M EDTA or ceftazidime/ceftazidime+0.2 M EDTA and the DDST with imipenem 10 mm apart from EDTA are the most effective methods for the detection of MBLs in Enterobacteriaceae

An Insight into the Factors Controlling Delta Flood Events: The Case of the Evros River Deltaic Plain (NE Aegean Sea)

The present contribution aims to give an insight into the main terrestrial and marine processes leading to delta flooding in the case of the transboundary Evros delta, located at the microtidal NE Aegean Sea, on the basis of recorded flood events in the Evros deltaic plain. The prevailing weather conditions at the onset of the event, along with sea-level rise above the mean state, portray the mechanism for the development of compound flood events and subsequent riparian flooding. This system blocks the riverine water's seaward exit, resulting in the flooding of the lower deltaic plain. The river discharge is recognized as a secondary factor acting mainly toward the persistence of the events. Several limitations restrict the quantification potential of the relative contribution of the key factors to the development, onset, and duration of a flood. Mitigation of the impacts of such flood events requires intercountry cooperation and a management plan based on a network of environmental monitoring

An Insight into the Factors Controlling Delta Flood Events: The Case of the Evros River Deltaic Plain (NE Aegean Sea)

The present contribution aims to give an insight into the main terrestrial and marine processes leading to delta flooding in the case of the transboundary Evros delta, located at the microtidal NE Aegean Sea, on the basis of recorded flood events in the Evros deltaic plain. The prevailing weather conditions at the onset of the event, along with sea-level rise above the mean state, portray the mechanism for the development of compound flood events and subsequent riparian flooding. This system blocks the riverine water’s seaward exit, resulting in the flooding of the lower deltaic plain. The river discharge is recognized as a secondary factor acting mainly toward the persistence of the events. Several limitations restrict the quantification potential of the relative contribution of the key factors to the development, onset, and duration of a flood. Mitigation of the impacts of such flood events requires intercountry cooperation and a management plan based on a network of environmental monitoring

Easy, Rapid, and Cost-Effective Methods for Identifying Carriers of Recurrent GJB2 Mutations Causing Nonsyndromic Hearing Impairment in the Greek Population

A variety of techniques have been developed for screening the GJB2 gene for known and unknown mutations, especially the most common mutation in the Caucasian population, the c. 35delG. Other mutations that have been so far characterized in the GJB2 gene seem to have different geographical distributions, and therefore there is an interest in identifying recurrent mutations specific for each population and developing easy and rapid screening techniques. Here we present easy screening protocols for already identified recurrent mutations in the Greek population. Developing easy, rapid, and cost-effective screening methods will facilitate the detection of GJB2 recurrent mutation carriers, at large, in the Greek population

Investigating the Climate-Related Risk of Forest Fires for Mediterranean Islands’ Blue Economy

The Mediterranean islands’ blue economy and, more specifically, the tourism sector, largely regulate Europe’s gross product. Climate change threatens the ecological, societal, and economic sustainability of the islands in many ways, with increasing wildfires making up one of the most critical components of the climate change impacts on tourism. Here, we aim to identify and assess forest fire vulnerability and risk due to climate change for seven Mediterranean islands through the application of the “impact chain” conceptual framework. The backbone of this approach requires the integration of quantitative and qualitative data according to the three main risk components sensu the Intergovernmental Panel on Climate Change (IPCC), i.e., hazard, exposure, and vulnerability, with a structured participatory approach involving stakeholders and experts. Our results illustrate the islands with high potential for improvement in terms of adapting capacity and, by indicating the contribution of the different risk components, highlight the main environmental and socio-economic elements that affect the islands’ vulnerability and risk under climate change. The approach’s potentials and constraints are discussed, suggesting that the method can be handily used to point out the priorities that must be addressed by mitigation and adaptation policies and measures at the island level

15-Year Analysis of Direct Effects of Total and Dust Aerosols in Solar Radiation/Energy over the Mediterranean Basin

The direct radiative effects of atmospheric aerosols are essential for climate, as well as for other societal areas, such as the energy sector. The goal of the present study is to exploit the newly developed ModIs Dust AeroSol (MIDAS) dataset for quantifying the direct effects on the downwelling surface solar irradiance (DSSI), induced by the total and dust aerosol amounts, under clear-sky conditions and the associated impacts on solar energy for the broader Mediterranean Basin, over the period 2003–2017. Aerosol optical depth (AOD) and dust optical depth (DOD) derived by the MIDAS dataset, along with additional aerosol and dust optical properties and atmospheric variables, were used as inputs to radiative transfer modeling to simulate DSSI components. A 15-year climatology of AOD, DOD and clear-sky global horizontal irradiation (GHI) and direct normal irradiation (DNI) was derived. The spatial and temporal variability of the aerosol and dust effects on the different DSSI components was assessed. Aerosol attenuation of annual GHI and DNI were 1–13% and 5–47%, respectively. Over North Africa and the Middle East, attenuation by dust was found to contribute 45–90% to the overall attenuation by aerosols. The GHI and DNI attenuation during extreme dust episodes reached 12% and 44%, respectively, over particular areas. After 2008, attenuation of DSSI by aerosols became weaker mainly because of changes in the amount of dust. Sensitivity analysis using different AOD/DOD inputs from Copernicus Atmosphere Monitoring Service (CAMS) reanalysis dataset revealed that using CAMS products leads to underestimation of the aerosol and dust radiative effects compared to MIDAS, mainly because the former underestimates DOD