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Recent technological developments in aviation, such as vertical take-off and landing and electric engines, are bringing the development of integrated urban air transport systems closer and are generally helping to promote the concept of Urban Air Mobility (UAM). UAM makes it possible to provide integrated air transport services for people and goods in urban areas, reducing travel time initially and leading to cost reductions in the future. The development of UAM will allow urban airspace to be used for short and medium range operations, potentially connecting larger urban areas or neighbouring cities. However, the operation of UAM requires, on the one hand, the development of appropriate urban infrastructure to provide full and vertical support for aircraft, such as vertical landing and take-off areas, specially designed intermediate areas for embarkation and disembarkation of passengers and cargo, as well as areas with operational technical bases for loading, parking and maintenance of aircraft. All this is the concept of the VertiPorts/Voloports/Vertistops. However, the development of a VertiPorts/Voloports/ Vertistops in the dense and complex modern urban environment can be challenging, as on the one hand specific rules for aviation safety have to be followed, and on the other hand their integration into the urban environment requires compliance with the rules of urban planning, land use and protection of private property.This paper presents the challenges that researchers have to face in order to integrate Voloports into an already formed and dense urban environment, such as that of the city Athens, the metropolitan centre and capital of Greece, in respect to various constitutional, institutional and spatial restrictions. [ABSTRACT FROM AUTHOR]

The article offers information on a study that calculated aerosol absorption properties for a 10 month period in Athens, Greece within the ultraviolet (UV) range. It mentions the use of the measurement of sun and sky radiance measured by CIMEL sunphotometer and total and diffuse ultraviolet (UV) irradiance. It states that based on the measurement that result to single scattering albedo (SSA) there are different compositions of aerosol.

The evolution of environmental changes during the last decades and the impact on the living biomass in the western part of Amvrakikos Gulf was investigated using abundances of benthic foraminifera and lipid biomarker concentrations. These proxies indicated that the gulf has dramatically changed due to eutrophication. Eutrophication has led to a higher productivity, a higher bacterial biomass, shifts towards opportunistic and tolerant benthic foraminifera species (e.g. B. elongata, N. turgida, T. agglutinans, A. tepida) and a lower benthic species density. Close to the Preveza Straits (connection between the gulf and the Ionian Sea), the benthic assemblages appeared to be less productive and more diversified under more oxygenated conditions. Sea grass meadows largely contributed to the organic matter at this sampling site. Isorenieratane, chlorobactane and lycopane together with oxygen monitoring data indicated that anoxic (and partly euxinic) conditions prevailed seasonally throughout the western part of the gulf with more severe hypoxia towards the east. Increased surface water temperatures have led to a higher stratification, which reduced oxygen resupply to bottom waters. These developments are reasons for mass mortality events and ecosystem decline observed in Amvrakikos Gulf. [ABSTRACT FROM AUTHOR]

The assessment of cropland carbon and nitrogen (C and N) balances plays a key role in identifying cost-effective mitigation measures to combat climate change and reduce environmental pollution. In this paper, a biogeochemical modelling approach is adopted to assess all C and N fluxes in a regional cropland ecosystem of Thessaly, Greece. Additionally, the estimation and quantification of the modelling uncertainty in the regional inventory are realized through the propagation of parameter distributions through the model, leading to result distributions for modelling estimations. The model was applied to a regional dataset of approximately 1000 polygons, deploying model initializations and crop rotations for the five major crop cultivations and for a time span of 8 years. The full statistical analysis on modelling results (including the uncertainty ranges given as ± values) yields for the C balance carbon input fluxes into the soil of 12.4 ± 1.4 t C ha -1 yr -1 and output fluxes of 11.9 ± 1.3 t C ha -1 yr -1 , with a resulting average carbon sequestration of 0.5 ± 0.3 t C ha -1 yr -1. The averaged N influx was 212.3 ± 9.1 kg N ha -1 yr -1 , while outfluxes of 198.3 ± 11.2 kg N ha -1 yr -1 were estimated on average. The net N accumulation into the soil nitrogen pools was estimated to be 14.0 ± 2.1 kg N ha -1 yr -1. The N outflux consists of gaseous N fluxes composed of N 2 O emissions of 2.6 ± 0.8 kg N 2 O–N ha -1 yr -1 , NO emissions of 3.2 ± 1.5 kg NO–N ha -1 yr -1 , N 2 emissions of 15.5 ± 7.0 kg N 2 –N ha -1 yr -1 and NH 3 emissions of 34.0 ± 6.7 kg NH 3 –N ha -1 yr -1 , as well as aquatic N fluxes (only nitrate leaching into surface waters) of 14.1 ± 4.5 kg NO 3 –N ha -1 yr -1 and N fluxes of N removed from the fields in yields, straw and feed of 128.8 ± 8.5 kg N ha -1 yr -1. [ABSTRACT FROM AUTHOR]

Heritage Building Information Modelling (HBIM) can be a valuable tool for the efficient management of cultural heritage. Adopting Building Information Modelling (BIM) for heritage architecture requires investing in training for modelling as-found elements, establishing standards for modelling, and developing accessible libraries of parametric assets. Parametric families of the Doric Order column and entablature were modelled in Autodesk Revit using standard measurements of the Doric Order, with parameters assigned to each element to remain adjustable and adapt to any as found project. These families were modelled with the ability to adjust all geometry to any point cloud with the intention of uploading the Revit files to an accessible online database, the Multimedia Inventory of Architectural Heritage (MIAH), developed by Carleton Immersive Media Studio (CIMS). The integration of these families into an online platform for any heritage professional to download and modify intends to ease the modelling process for future projects, as well as standardize the families used in future projects. To define the process of collecting data for as-found modelling, this paper outlines the documentation and data processing for two archaeological sites on the islands of Rhodes and Kos in Greece. To assist future HBIM library users in understanding the families, the process of converting point cloud to HBIM is demonstrated through the development of a parametric HBIM of the Temple of Hephaestus, located in Athens, Greece. [ABSTRACT FROM AUTHOR]

The Byzantine Empire has bequeathed to us a rich legacy of Christian churches, many of which possess historical and cultural significance. Unfortunately, the majority of these structures are currently undergoing a process of decay, having not received adequate preservation efforts. Moreover, the absence of collaboration between researchers in the various fields, each with their own focus on the study of Byzantine churches, presents a pressing need for dialogue and a collective response from these researchers. The region of Laconia, located in the south of Greece, is particularly in need of immediate attention, given the abundance of churches located therein. To address these challenges, the authors propose a novel approach involving the documentation of these churches in a digital format through the presentation of 3D models as scholarly editions that incorporate all available data sets in a multimedia format. This paper delineates several requisite specifications for 3D scholarly editions, which hold the key to solving the twin problems faced by Byzantine churches, namely, their protection and the scarcity of interdisciplinary collaboration amongst researchers. With 3D scholarly editions based on multimedia resources and adequate information management, it will be possible to facilitate collaboration and research between various fields of Byzantine studies, and beyond. Such efforts will serve to ensure that cultural heritage passed down from previous generations will be transmitted to future ones. [ABSTRACT FROM AUTHOR]

The article presents a study which provides an inter-comparison of lidar and ceilometer retrievals for determining the structure of the Planetary Boundary Layer (PBL) and profiling of tropospheric aerosol over Athens, Greece. The study was conducted under different aerosol concentrations including biomass burning, urban air pollution and the Saharan dust event. The limitations of each instrument are also examined.

The recent emergence of the Internet of Things (IoT), the latest technological innovations and the widespread use and embrace of Building Information Models (BIMs) offer several new ideas and decision-making capabilities throughout the life cycle of the built environment. The ability to connect and monitor data from sensor networks remotely in real time as well as the simulation and optimization of engineering systems, have led to the emergence of the Digital Twin (DT) concept of the structured environment. Although BIM lacks semantic completeness in areas beyond the scope of building modelling such as control systems, cadastral systems, networking of sensors, meteorological networks, etc., the DTs aim to achieve the synchronization of big data from various sources and simulate the real world into a virtual platform for the seamless management and control of the construction process, facility management, environmental monitoring, disaster management and disaster prevention, and other life cycle processes within the built environment. DTs in the built environment are still in nascent stages and thus a more in-depth investigation is required to explore and establish the best practices and technologies to serve this evolution. In this paper, we propose a methodology for providing the DT of a building; by crossing from the BIM static world to the dynamic cyber-world of DTs. A practical application is implemented for a two-storey 'smart' building with sensor systems installed in its assets and in the surrounding landscape area. As the practical experiment is successfully completed, we conclude that such an endeavour can actually be achieved at building level offering several economic, environmental and social benefits. [ABSTRACT FROM AUTHOR]

In this paper, we have developed three algorithms, namely hybrid weighted particle swarm optimization (wPSO) with the gravitational search algorithm (GSA), known as wPSOGSA; GSA; and PSO in MATLAB to interpret one-dimensional magnetotelluric (MT) data for some corrupted and non-corrupted synthetic data, as well as two examples of MT field data over different geological terrains: (i) geothermally rich area, island of Milos, Greece, and (ii) southern Scotland due to the occurrence of a significantly high electrical conductivity anomaly under crust and upper mantle, extending from the Midland Valley across the Southern Uplands into northern England. Even though the fact that many models provide a good fit in a large predefined search space, specific models do not fit well. As a result, we used a Bayesian statistical technique to construct and assess the posterior probability density function (PDF) rather than picking the global model based on the lowest misfit error. The study proceeds using a 68.27 % confidence interval for selecting a region where the PDF is more prevalent to estimate the mean model which is more accurate and close to the true model. For illustration, correlation matrices show a significant relationship among layer parameters. The findings indicate that wPSOGSA is less sensitive to model parameters and produces more stable and reliable results with the least uncertainty in the model, compatible with existing borehole samples. Furthermore, the present methods resolve two additional geologically significant layers, one highly conductive (less than 1.0 Ωm) and another resistive (300.0 Ωm), over the island of Milos, Greece, characterized by alluvium and volcanic deposits, respectively, as corroborated by borehole stratigraphy. [ABSTRACT FROM AUTHOR]

The restoration of cultural heritage sites is a complex and challenging process, particularly when the structure holds significant historical and cultural value. This paper refers to the first stages of the restoration study of Pashas Bridge, one of the largest stone bridges in Greece that was destroyed during World War II and further damaged by an earthquake in 1995. The project was assigned to multiple research groups from the Aristotle University of Thessaloniki (AUTh) for a period of 18 months by the Greek Ministry of Culture and Sports. To restore the bridge effectively, it is essential to accurately record, document, and assess its current condition. Through the use of photogrammetry, which creates 3D models of objects or structures using images, and unmanned aerial vehicles (UAVs) which assisted in capturing multiple shots with various angles of the bridge, a detailed 3D model of the bridge's current condition was generated. In addition to these technical approaches, historical research and documentation were utilized to understand the bridge's cultural heritage value. The process included an examination of historical photographs and records related to the bridge, with a constant effort to discover additional information about its history and importance. Ultimately, the restoration process of Pashas Bridge serves as a valuable case study for the effective restoration of cultural heritage sites. Through utilizing these resources, the team aims to restore the bridge to its former glory, preserving its cultural heritage value and ensuring its place as a valuable and integral part of the community for generations to come. [ABSTRACT FROM AUTHOR]

During the past 15 years photogrammetric practice has experienced an unprecedented change by the influence of computer vision algorithms, which support an almost completely automated processing. It is widely acknowledged that this fact has "democratized" Photogrammetry a lot, in the sense that it has become almost everyone's tool. However, this radical change has been met by scepticism by traditional photogrammetrists, who claim that such tools may lead to geometrically wrong and inaccurate results if not accompanied by thorough projection and error checks and evaluation of the correctness of results.In this paper, the two approaches are briefly described on the basis of the geometric documentation of a cultural heritage funerary monument situated in the archaeological site of Messini in Southern Greece. An effort is made for highlighting the obvious advantages of each approach but also indicating their disadvantages. Applications, subject to different requirements and processing procedures are identified, rationalizing that conventional photogrammetric procedures still cannot be easily replaced. [ABSTRACT FROM AUTHOR]

The paper proposes a survey of the port of Fiskardo, a village located north of the island of Kefalonia, the largest of the Ionian Islands, in Greece. Called the "Venice of the South" as the coloured elevations of the houses, the subject of the research, are similar to Venetian buildings, Fiskardo owes its name to Roberto d'Altavilla who founded a Frankish colony in this bay.The study, starting with archival iconographic research, was carried out with the support of the photogrammetric technique supported by a four-helix drone allowed the documentation of the cultural heritage. This activity is configured as a search for identity characteristics through actions of knowledge of the places and geometries of the port through the use of UAV technologies. [ABSTRACT FROM AUTHOR]

The recovery phase of an earthquake-affected settlement is a time-consuming and complex process that requires monitoring, which is now possible using UAS. The purpose of this paper is to present the methodology followed and the results obtained by the exploitation of UAS for rapid multitemporal 3D mapping during the recovery phase of Vrisa traditional settlement, Lesvos island, Greece, which was highly damaged by the earthquake (Mw=6.3) on 12th June 2017. More analytically, three (3) flight campaigns covering the period July 2017 – May 2020 took place by means of an UAS for collecting high-resolution images on: i) 19th May 2019, ii) 29th September 2019, iii) 17th May 2020. Structure from Motion (SfM) and Multi Stereo View (MSV) methods have been applied and produced: i) Digital Surface Models – DSMs, ii) 3D Point Clouds – 3DPC and iii) Orthophoto-maps, of Vrisa. In parallel, GIS capabilities has been exploit to calculate building volumes based on: a) DSM produced by UAS image processing, b) DEM produced by 233 RTK measurements and c) building footprints derived by the digitization of the orthophoto-map of 25th July 2017. The methodology developed and implemented achieves extremely reliable results in a relatively easy, fast and economically feasible way, which is confirmed with great precision by field work. By applying the above-described methodology, it was possible to monitoring the recovery phase during July 2017 and May 2020 which 302/340 buildings that had been severely damaged by the earthquake have been demolished. A small number of new buildings have also been rebuilded and small number of buildings that have just begun excavations for their construction. An important parameter for obtaining reliable data and comparable results is the correct selection of flight parameters and their maintenance at all times when it is decided to take data, without affecting the accuracy of the results from taking photos or videos. Automation in the future of the proposed methodology can significantly accelerate the achievement of reliable results without the intermediate interpretation of orthophoto-maps. [ABSTRACT FROM AUTHOR]

This paper aims to study wet–cold compound events (WCCEs) in Greece for the wet and cold season November–April since these events may affect directly human activities for short or longer periods, as no similar research has been conducted for the country studying the past and future development of these compound events. WCCEs are divided into two different daily compound events, maximum temperature– (TX) accumulated precipitation (RR) and minimum temperature– (TN) accumulated precipitation (RR), using fixed thresholds (RR over 20 mm d -1 and temperature under 0 ∘ C). Observational data from the Hellenic National Meteorology Service (HNMS) and simulation data from reanalysis and EURO-CORDEX models were used in the study for the historical period 1980–2004. The ensemble mean of the simulation datasets from projection models was employed for the near future period (2025–2049) to study the impact of climate change on the occurrence of WCCEs under the Representative Concentration Pathways (RCPs) 4.5 and 8.5 scenarios. Following data processing and validation of the models, the potential changes in the distribution of WCCEs in the future were investigated based on the projected and historical simulations. WCCEs determined by fixed thresholds were mostly found over high altitudes with TN–RR events exhibiting a future tendency to reduce particularly under the RCP 8.5 scenario and TX–RR exhibiting similar reduction of probabilities for both scenarios. [ABSTRACT FROM AUTHOR]

The Historic Center (Chorá) of Patmos, located in one of the Dodecanese Islands of Greece, was inscribed in the World Heritage List in 1999. The morphological feature, the housing typologies and the building techniques that characterize the Chorá provide an authentic and astonishing expression of the stylistic and typological models of the vernacular architecture of the Greek islands. This paper presents part of the research carried out on the Chorá of Patmos, within the 3D Past project, funded by the European Creative Europe program. The first part illustrates the results of the research concerning the analysis of the material components of the architectural heritage of Patmos: the urban structure, the evolution of the main architectural typologies, the feature of the main building systems. The second part of the paper presents the application of the Heritage Impact Assessment (HIA), a tool for the management of site transformations and in particular for identifying, forecasting and evaluating the impact of potential development on the Outstanding Universal Value (OUV) of the properties. In the case of Patmos the application of HIA can provide an important contribution to manage changes and future transformations in order to preserve the cultural significance of the site and ensure its sustainable development. [ABSTRACT FROM AUTHOR]

This article describes the ways a smart city can use Geospatial Information Systems (G.I.S.) to promote its history, focusing on the phenomenon of piracy. Specifically, definitions are given regarding the concept of Smart Cities and their correlation with G.I.S. Then an analysis is made concerning the ways in which historical phenomena, such as piracy, can be visualized using G.I.S. through the creation of interactive maps, 3D models and animated maps. References to historical facts are also presented in order to understand the need of creating such cartographic compositions to highlight aspects of history, that few know and even fewer have studied, especially in Greece. Moreover, we present the ways in which cartographic compositions can be demonstrated in the coastal settlements and the islands that were pirate strongholds. Finally, we show ways that these cartographic compositions can be hosted on a website, giving the possibility to access the information from all over the world, emphasizing the importance of highlighting local history. [ABSTRACT FROM AUTHOR]

The growing interest within the construction industry in the preservation, rehabilitation, and conservation of heritage-value buildings has led to the implementation of Historic Building Information Modelling (HBIM). Especially in Greece, where the number of historical buildings is considerably large, having efficient and standardized processes of Cultural Heritage management and conservation becomes a prerequisite. The rigorously accurate representation of old constructions requires specific geometric modelling processes in order to generate the necessary relevant libraries of parametric objects. This paper describes the development of a parametrized library for the main parts of a Doric Temple to be used for introducing such parts in an HBIM system. Moreover, to verify the correctness of the parametrized column an application is performed in which the dimensions of a real column are compared with the dimensions of the standard one. The study improves the potential of the BIM process for its application to buildings with distinctive architecture in the context of the preservation or conversion of heritage buildings. In first section the term HBIM is explained and its usefulness to cultural heritage (CH) is justified. Section 2 describes previous attempts to create HBIM libraries for historic structures. After that, the construction of parametric model, which was created with visual programming Dynamo, is presented. Finally, the efficiency of the adjustment of a standard column to a given point cloud is described and in the end the results of the application are compared and discussed. [ABSTRACT FROM AUTHOR]

The paper presents the application of an islands' smartification and sustainability index the Smart Sustainable Islands Index or S2I2. In addition to the classic parameters, the index is designed to include and emphasize specific parameters of the islands that are not usually found or they are less important in a mainland city. The structure and parameters of the index are presented and compared to other initiatives A database with a corresponding web page has been created in order to collect data from the islands for their index calculation. The database structure and relationships are presented, as well as, the user interaction and data collection forms. After the online system finalization, each island in Greece, Europe, or in the World will have the possibility to submit the required information & data and will be able to see the graphic representation of the results and the rank of the island in terms of smartification and sustainability. The fully functioning system is expected to support significantly an islands' effort for a smarter, greener & sustainable development. [ABSTRACT FROM AUTHOR]

Risk assessment constitutes the first part within the risk management framework and involves evaluating the importance of a risk, either quantitatively or qualitatively. Risk assessment consists of three steps, namely risk identification, risk estimation and risk evaluation. Nevertheless, the risk management framework also includes a fourth step, i.e., the need for feedback on all the risk assessment undertakings. However, there is a lack of such feedback, which constitutes a serious deficiency in the reduction of environmental hazards at the present time. Risk identification of local or regional hazards involves hazard quantification, event monitoring including early warning systems and statistical inference. Risk identification also involves the development of a database where historical hazard information and hazard effects are included. Similarly, risk estimation involves magnitude–frequency relationships and hazard economic costs. Furthermore, risk evaluation consists of the social consequences of the derived risk and involves cost-benefit analysis and community policy. The objective of this review paper is twofold. On the one hand, it is to address meteorological hazards and extremes within the risk management framework. Analysis results and case studies over Mediterranean ecosystems with emphasis on the wider area of Greece, in the eastern Mediterranean, are presented for each of the three steps of risk assessment for several environmental hazards. The results indicate that the risk management framework constitutes an integrated approach for environmental planning and decision-making. On the other hand, it sheds light on advances and current trends in the considered meteorological and environmental hazards and extreme events, such as tornadoes, waterspouts, hailstorms, heat waves, droughts, floods, heavy convective precipitation, landslides and wildfires, using recorded datasets, model simulations and innovative methodologies. [ABSTRACT FROM AUTHOR]

The assessment of cropland carbon and nitrogen (C & N) balances play a key role to identify cost effective mitigation measures to combat climate change and reduce environmental pollution. In this paper, a biogeochemical modelling approach is adopted to assess all C & N fluxes in a regional cropland ecosystem of Thessaly, Greece. Additionally, the estimation and quantification of the modelling uncertainty in the regional inventory are realized through the propagation of parameter distributions through the model leading to result distributions for modelling estimations. The model was applied on a regional dataset of approximately 1000 polygons deploying model initializations and crop rotations for the 5 major crop cultivations and for a timespan of 8 years. The full statistical analysis on modelling results yields for the C balance carbon input fluxes into the soil of 12.4 ± 1.4 tons C ha-1 yr-1 and output fluxes of 11.9 ± 1.3 tons C ha-1 yr-1, with a resulting average carbon sequestration of 0.5 ± 0.3 tons C ha-1 yr-1. The averaged N influx was 212.3 ± 9.1 kg N ha-1 yr-1 while outfluxes were estimated on average of 198.3 ± 11.2 kg N ha-1 yr-1. The net N accumulation into the soil nitrogen pools was estimated to 14.0 ± 2.1 kg N ha-1 yr-1. The N outflux consist of gaseous N fluxes composed by N2O emissions 2.6 ± 0.8 kg N2O-N ha-1 yr-1, NO emissions of 3.2 ± 1.5 kg NO-N ha-1 yr-1, N2 emissions 15.5 ± 7.0 kg N2-N ha-1 yr-1 and NH3 emissions of 34.0 ± 6.7 kg NH3-N ha-1 yr-1, as well as aquatic N fluxes (only nitrate leaching into surface waters) of 14.± 4.5 kg NO3-N ha-1 yr-1, N fluxes of N removed from the fields in yields, straw and feed of 128.8 ± 8.5 kg N ha-1 yr-1. [ABSTRACT FROM AUTHOR]

With epidemics blocking offline interactions, it is difficult to organise events such as tours of major heritage sites and outbound exhibitions of cultural relics, and new paths need to be expanded for the presentation of cultural heritage and intercultural education efforts. With the booming development of digital technology, the integration of online virtual presentation and interactive technology and the innovative design of 3D scenes provide new solutions for the intercultural communication of these precious and immovable cultural relics (e.g. archaeological sites), etc. This project is based on the Sino-Greek cooperation around the online presentation of heritage items such as the Terracotta Warriors and Horses of China and the precious collection of the National Archaeological Museum of Greece, in order to present and On the basis of communicating the value of heritage and the connection between Chinese and Greek civilisations, the project explores the development of a virtual space that integrates the Terracotta Warriors and Horses pits, the interactive virtual display of cultural relics, and the display of the achievements of scientific and technological conservation of cultural relics, so as to realise the cross-cultural exchange between China and Greece and fulfil the educational function of heritage. [ABSTRACT FROM AUTHOR]

In recent years 3D building modelling techniques are commonly used in various domains such as navigation, urban planning and disaster management, mostly confined to visualization purposes. The 3D building models are produced at various Levels of Detail (LOD) in the CityGML standard, that not only visualize complex urban environment but also allows queries and analysis. The aim of this paper is to present the methodology and the results of the comparison among two scenarios of LOD2 building models, which have been generated by the derivate UAS data acquired from two flight campaigns in different altitudes. The study was applied in Vrisa traditional settlement, Lesvos island, Greece, which was affected by a devastating earthquake of Mw = 6.3 on 12th June 2017. Specifically, the two scenarios were created by the results that were derived from two different flight campaigns which were: i) on 12th January 2020 with a flying altitude of 100 m and ii) on 4th February 2020 with a flying altitude of 40 m, both with a nadir camera position. The LOD2 buildings were generated in a part of Vrisa settlement consisted of 80 buildings using the footprints of the buildings, Digital Surface Models (DSMs), a Digital Elevation Model (DEM) and orthophoto maps of the area. Afterwards, a comparison was implemented between the LOD2 buildings of the two different scenarios, with their volumes and their heights. Subsequently, the heights of the LOD2 buildings were compared with the heights of the respective terrestrial laser scanner (TLS) models. Additionally, the roofs of the LOD2 buildings were evaluated through visual inspections. The results showed that the 65 of 80 LOD2 buildings were generated accurately in terms of their heights and roof types for the first scenario and 64 for the second respectively. Finally, the comparison of the results proved that the generation of post-earthquake LOD2 buildings can be achieved with the appropriate UAS data acquired at a flying altitude of 100 m and they are not affected significantly by a lower one altitude. [ABSTRACT FROM AUTHOR]

The already arduous task of collecting, processing and managing heterogeneous cultural heritage data is getting more intense in terms of indexing, interaction and dissemination. This paper presents the creation of a 4D web-based platform as a centralized data hub, moving beyond advanced photogrammetric techniques for 3D capture and multi-dimensional documentation. Precise metric data, generated by a combination of image-based, range and surveying techniques, are spatially, logically and temporally correlated with cultural and historical resources, in order to form a critical knowledge base for multiple purposes and user types. Unlike conventional information systems, the presented platform, which adopts a relational database model, has the following front-end functionalities: (i) visualization of high-resolution 3D models based on distance dependent Level of Detail (LoD) techniques; (ii) web Augmented Reality; and (iii) interactive access and retrieval services. Information deduced from the developed services is tailored to different target audiences: scientific community, private sector, public sector and general public. The case study site is the UNESCO world heritage site of Meteora, Greece, and particularly, two inaccessible huge rocks, the rock of St. Modestos, known as Modi, and the Alyssos rock. [ABSTRACT FROM AUTHOR]

Tactile maps are accessible for visually impaired people. Therefore, studies on the use of graphic variables in tactile cartography are necessary. A search for papers related to the keyword "tactile map" was conducted in the Scopus database and in the annals of the International Cartographic Conference, between the years 2009 and 2019, with the objective of identifying in the international literature the topics concerning to graphic variables, especially those related to color code systems. Among the full manuscripts found in the Scopus and International Cartographic Association databases, the countries with the largest number of publications in the tactile cartography field were Brazil, United States, Greece, Spain and Germany. The main topics related to tactile maps in the last 10 years were: visual impairment, navigation and wayfinding, perception, universal design, among others. Some of the papers suggest the representation of colors for colorblind people, but there is a gap regarding the use of color codes as graphic variables on tactile maps. [ABSTRACT FROM AUTHOR]

This paper aims at reconstructing the palaeoclimatic changes during the last 2600 years in southern Greece based on a proxy record from Lake Trichonida. For the first time, we provide a reliable age-depth model and continuous geochemical data for the largest and deepest lake in Greece. We use X-ray fluorescence (XRF) geochemical data supported by discrete mineral analysis based on X-ray diffraction (XRD), grain size distribution, and organic matter content to investigate changes in the lake sedimentary system and identify the major forcing mechanisms. A principal component analysis based on the XRF geochemical composition identifies the variation between carbonate-rich material, precipitating predominantly under drier and/or warmer conditions, and terrigenous sediment input, with it being more prominent during wetter and/or colder conditions. The first principal component (PC1) shows a very strong correlation with the weathering proxy log⁡(Rb/Sr) , and we interpret both proxies as depicting fluctuations in the hydrological conditions. A cluster analysis, conducted on the continuous geochemical and colour parameters, highlights the similarities in the sediment characteristics deposited during wetter phases, notably during 1850–1750, 1500–1400, ca. 1100, and ca. 100 cal BP. When comparing the PC1 Trichonida record to independent records from the Balkans, we find generally concurring patterns on a multi-decadal to centennial scale. We show that phases with wetter conditions at Lake Trichonida coincide with a more negative North Atlantic Oscillation (NAO) index, suggesting that the precipitation variability in southern Greece is linked to changes in the NAO atmospheric pattern, as one major driving force. The 2600-year-long sedimentary record of Lake Trichonida contributes to a better understanding of Late Holocene palaeohydrological changes in an important climatic transitional zone in the eastern Mediterranean. Kurzfassung: In diesem Artikel rekonstruieren wir paläoklimatische Veränderungen der vergangenen 2600 Jahre in Südgriechenland anhand von Proxies aus dem See Trichonida. Erstmals stellen wir ein verlässliches Alterstiefenmodell, sowie durchgängige, geochemische Daten für den größten griechischen See zur Verfügung. Wir verwenden geochemische Daten aus Röntgenfluoreszenzanalyse (XRF), unterstützt durch diskrete Röntgen-Diffraktometrie (XRD), Korngrößenverteilungen und Messungen des Organikgehalts, um Änderungen im sedimentären System des Sees zu untersuchen und deren Haupteinflussfaktoren zu ermitteln. Mittels einer Hauptkomponentenanalyse der geochemischen Zusammensetzung, basierend auf den XRF Messungen, identifizieren wir als dominierenden Prozess die Schwankungen zwischen Carbonaten auf der einen Seite, welche vorrangig während trockener und/oder wärmerer Bedingungen ausfallen, und terrigenem Material auf der anderen Seite, welches insbesondere in feuchteren und/oder kühleren Phasen eingetragen wird. Wir interpretieren diese Schwankungen als Änderungen in den hydrologischen Gegebenheiten. Ein Vergleich der ersten Hauptkomponente (PC1) mit dem Verwitterungsproxy log⁡(Rb/Sr) weist hohe Übereinstimmungen auf, und wir interpretieren beide als Proxies für Schwankungen in den hydrologischen Gegebenheiten. Eine Clusteranalyse, basierend auf den kontinuierlichen geochemischen sowie Farbwerten, verdeutlicht die Ähnlichkeiten in den Eigenschaften der Sedimente, welche während feuchterer Phasen abgelagert wurden, insbesondere in den Zeiträumen 1850–1750, 1500–1400, ca. 1100 und ca. 100 cal BP. Der Vergleich des PC1 Trichonida Datensatzes mit unabhängigen Proxies anderer Studien aus der Balkanregion zeigt grundsätzlich übereinstimmende Muster auf multidekadischen bis hundertjährigen Zeitskalen. Wir zeigen, dass Phasen mit feuchteren Bedingungen im Einzugsgebiet des Sees Trichonida mit einem negativen Index der Nordatlantischen Oszillation (NAO) zusammenfallen, woraus sich schließen lässt, dass die Niederschlagsvariabilität in Südgriechenland zu einem Großteil von Veränderungen im Muster der NAO geprägt ist. Der 2600 Jahre abdeckende Sedimentkern aus dem See Trichonida trägt zu einem besseren Verständnis natürlicher, spätholozäner paläohydrologischer Schwankungen in einer klimatisch wichtigen Übergangszone im östlichen Mittelmeer bei. [ABSTRACT FROM AUTHOR]

The interest in the documentation and enhancement of Underwater Cultural Heritage (UCH) is rising rapidly over the last decades. This has happened especially due to the significant technological advances, which have enabled the digital data acquisition in the hostile underwater environment. Numerous efforts have been made so far concerning the 3D digitisation and promotion of the UCH using photogrammetric methods and 3D surveys in order on one hand to document the site and on the other to develop virtual and augmented reality applications and make this part of the hidden cultural heritage accessible to people with difficulties to reach it.This paper presents the methodology, the actions and decisions that were taken for the geometric documentation, study, promotion and enhancement of the remains of a roman villa located at Agios Vlassis, in Ancient Epidaurus in Greece. The present effort focuses on the use of low-cost equipment in order to acquire the necessary digital data to produce the 3D textured model of the archaeological site and the required 2D documentation products. The methods used to produce this 3D model involve contemporary computer vision algorithms adapted to confront the challenge of processing a huge number of images and extracting useful metric information from them. Moreover, the creation and programming process of two virtual reality applications is described. By developing a virtual tour and a virtual reality application, it is hoped to raise the awareness about UCH and give prominence to different means and ways of protection and management of underwater archaeological sites. [ABSTRACT FROM AUTHOR]

Archaeology as a science is based on finding and displaying the remains of the past. In recent years, with the progress of technology, the science of archeology has been expanding and evolving. Three-dimensional digitization has become an integral part of the archiving, documentation and restoration effort of cultural heritage, offering important benefits in studies for reconstruction and restoration tasks of architectural creations, archaeological sites, historic monuments and objects of art in general. The three-dimensional models are now available for many applications. In this paper such 3D models of two prominent Macedonian tombs in Northern Greece were exploited for their virtual restoration. Virtual restoration of monuments is of special importance to archaeological research, as it provides the necessary tools to investigate alternative solutions to the serious issue of archaeological restoration. These solutions do not interfere with the real monument, thus respecting its value and the international conventions. Digital 3D models have begun to be more beneficial in a science such as archaeology as they offer easy access to both archaeological and geometric information to a wider audience as well as a high degree of interaction possibilities with the user. [ABSTRACT FROM AUTHOR]

Τhe development in the fields of Underwater Cultural Heritage (UCH) management and Maritime Archaeology, yields an interdisciplinary and creative academic framework, such as the Information and Communication Technologies (ICT) sector that has been proved to build intelligent systems and applications. However, the ways to fully make use of these technologies are still being explored, as their potential have not been exploited yet. Underwater archaeological sites, semi (/or fully) submerged settlements, ancient ports and shipwrecks, unlike land sites, are not accessible to public due to their special (sub) marine environment and depth. In this paper, an innovative research idea of using Augmented Reality (AR) for maintaining the memory and the information of underwater archaeological sites, is presented. Although the "artificial" visual documentation cannot replace the authentic values of the underwater tangible heritage, the AR technology can contribute to the protection of the intangible properties and the conquered knowledge of the past of a place. This research work will focus, among other case studies, on the (semi) submerged fortifications and their contiguous contents of the acropolis of Halai in east Lokris, Greece. Hence, along with the climate change that may lead more antiquities covered by water during the following years, the advances in the communication field and the up-coming 5G and cloud technologies will make the idea fully applicable, contributing to the enhancement of the coastal and the underwater archaeological remains. [ABSTRACT FROM AUTHOR]

Deep Learning (DL) ingrained into Mobile Augmented Reality (MAR) enables a new information-delivery paradigm. In the context of 6 DoF pose estimation, powerful DL networks could provide a direct solution for AR systems. However, their concurrent operation requires a significant number of computations per frame and yields to both misclassifications and localization errors. In this paper, a hybrid and lightweight solution on 3D tracking of arbitrary geometry for outdoor MAR scenarios is presented. The camera pose information obtained by ARCore SDK and vSLAM algorithm is combined with the semantic and geometric output of a CNN-object detector to validate and improve tracking performance in large-scale and uncontrolled outdoor environments. The methodology involves three main steps: i) training of the Mask-R CNN model to extract the class, bounding box and mask predictions, ii) real-time detection, segmentation and localization of the region of interest (ROI) in camera frames, and iii) computation of 2D-3D correspondences to enhance pose estimation of a 3D overlay. The dataset holds 30 images of the rock of St. Modestos – Modi in Meteora, Greece in which the ROI is an area with characteristic geological features. The comparative evaluation between the prototype system and the original one, as well as with R-CNN and FAST-R CNN detectors demonstrates higher precision accuracy and stable visualization at half a kilometre distance, while tracking time has decreased at 42% during far-field AR session. [ABSTRACT FROM AUTHOR]

This paper aims to study wet-cold compound events (WCCEs) over Greece for the wet and cold season November-April. WCCEs are divided in two different compound events (TX-RR) and (TN-RR) and two different approaches using fixed (RR over 20 mm/day and Temperature under 0 °C) and percentile (RR over 95th and Temperature under 5th) thresholds. Observational data from the Hellenic National Meteorology Service (HNMS) and simulation data from reanalysis and EUROCORDEX models were used in the study for the historical period 1980-2004. Simulation datasets from projection models were employed for the near future period (2025-2049) to study the impact of climate change on the occurrence of WCCEs under RCP 4.5 and 8.5 scenarios. Following data processing and validation of the models, the potential changes in the distribution of WCCEs in the future were investigated based the projected and historical simulations. WCCEs determined by fixed thresholds were mostly found over high altitudes with a future tendency to reduce particularly under RCP 8.5. On the other hand, WCCEs obtained with percentile thresholds, were distributed mostly in Eastern Greece and Crete while their changes differed significantly among models. [ABSTRACT FROM AUTHOR]

The current paper is a part of the scientific category HBIM, with ground photography and photogrammetric processing. The photogrammetry is an important tool for recording, storing, promoting and documenting buildings. The purpose of the work is to construct a three-dimensional model of the Greek-Roman aqueduct of the city of Kavala, in northern Greece. First of all, the aqueduct has a very important historical and aesthetic value for the city, because it is a tourist attraction. Also, it is an urban physical boundary, which separates part of the old town from the new roads of the coastal front. Moreover, the methodology was based on photographic shots, then on photogrammetric processing with Zephyr software. The methodology of the 3D model had as a purpose the terrestrial photography in a rapid and effective way. The result, of the work is the presentation of the three-dimensional model of the aqueduct, the analysis of the methodological steps of photogrammetric processing and the analysis of the historical transformation of the aqueduct area by a medieval and modern coastal city. The advantages of photogrammetric documentation have a role in the storage of the three-dimensional form of the historical building and in the smart promotion of its historical, touristic, urban aspects. [ABSTRACT FROM AUTHOR]

Secondary inorganic aerosols (SIAs) are major components of fine particulate matter (PM 2.5), having substantial implications for climate and air quality in an urban environment. In this study, a state-of-the-art thermodynamic model has been coupled to the source dispersion and photochemistry city-scale chemistry transport model EPISODE–CityChem, which is able to simulate pollutants at a horizontal resolution of 100m×100m , to determine the equilibrium between the inorganic gas and aerosol phases over the greater Athens area, Greece, for the year 2019. In agreement with in situ observations, sulfate (SO42-) is calculated to have the highest annual mean surface concentration (2.15 ± 0.88 µgm-3) among SIAs in the model domain, followed by ammonium (NH4+ ; 0.58 ± 0.14 µgm-3) and fine nitrate (NO3- ; 0.24 ± 0.22 µgm-3). Simulations denote that NO3- formation strongly depends on the local nitrogen oxide emissions, along with the ambient temperature, the relative humidity, and the photochemical activity. Additionally, we show that anthropogenic combustion sources may have an important impact on the NO3- formation in an urban area. During the cold period, the combined effect of decreased temperature in the presence of non-sea-salt potassium favors the partitioning of HNO3 in the aerosol phase in the model, raising the NO3- formation in the area. Overall, this work highlights the significance of atmospheric composition and the local meteorological conditions for the equilibrium distribution of nitrogen-containing semi-volatile compounds and the acidity of inorganic aerosols, especially in urban areas where atmospheric trace elements from natural and anthropogenic sources coexist. [ABSTRACT FROM AUTHOR]

This paper introduces the development of a database of high-impact weather events that occurred in Greece since 2001. The selected events are related to the occurrence of floods, flash floods, hail, snow/frost, tornados, windstorms, heat waves and lightning with adverse consequences (excluding those related to agriculture). The database includes, among others, the geographical distribution of the recorded events, relevant meteorological data, a brief description of the induced impacts and references in the press. This paper further offers an extensive analysis of the temporal and spatial distribution of high-impact weather events for the period 2001-2011, taking into account the intensity of weather conditions and the consequent impact on the society. Analysis of the monthly distribution of high-impact weather events showed that they are more frequent during October and November. More than 80 people lost their lives, half of which due to flash floods. In what concerns the spatial distribution of high-impact weather events, among the 51 prefectures of the country, Attica, Thessaloniki, Elia and Halkidiki were the most frequently affected areas, mainly by flash floods. Significant was also the share of tornados in Elia, of windstorms in Attica, of lightning and hail events in Halkidiki and of snow/frost events in Thessaloniki. [ABSTRACT FROM AUTHOR]

Turkey and neighborhood countries like Greece and Iran are situated on an active earthquake region. Masonry type structures are very common on these countries, especially on the rural areas. During the last earthquakes, several masonry type houses were collapsed, causing loss of life and property. Strengthening methods of masonry houses were discussed in this study. The paper summarizes the results of a experimental programme carried out on models, scaled 1/10, of one-storey masonry buildings. First specimen tested was the reference specimen and used for comparison purposes. Other specimens contained several strengthening strategies. A total of 9 specimens were tested. The results allow to assess the efficiency of the various strengthening techniques employed. [ABSTRACT FROM AUTHOR]

Augmented Reality (AR) is more than an added value for Cultural Heritage (CH); it is vital for its sustainability, promotion and dissemination, increasing accessibility in CH even during difficult periods of time, like the Covid-19 pandemic. In order to be meaningful and engaging, an AR application should have the following characteristics: easiness of use, high-quality representations and compatibility. This paper presents a marker-less mobile AR application for the display and inspection of high-resolution 3D cultural assets, overlayed on a particular location in the real-world scene. Instead of predefined markers, an image captured by the user is exploited as a pattern for real-time feature matching, pose estimation and scene augmentation. Our approach is based on pure computer vision and photogrammetric techniques, implemented using native C++ and Java code for Android mobile platforms. It is built with the use of the OpenCV library and the OpenGL ES graphics API without any dependencies of AR Software Development Kits (SDKs). Therefore, it supports cross-vendor portability regarding mobile model devices and hardware specifications. The evaluation of the developed application examines the performance of various matching techniques and the overall responsiveness of processing and 3D rendering on mid-range and low-end smartphones. The results showcase the reliability and responsiveness of the pattern recognition as well as the potential of the 3D graphics engine to render and overlay complex 3D models balancing between visual quality and time. The proposed methodology is applied to the Ciborium of the church of St. Charalabos, located at St. Stephen's Monastery in Meteora, Greece. [ABSTRACT FROM AUTHOR]

In this work the problem of change detection in high-resolution (HR) satellite images is addressed. The active learning (AL) algorithm Bayesian active learning disagreement (BALD) is applied on WorldView images of urban and suburban areas in the island of Crete, Greece. Comparisons with results from random sampling (RS) on AL are carried out. Several cases of selecting different amounts of images in the training set of a convolutional neural network (CNN) are experimented. The results show that the validation accuracy of classification as changed or unchanged of the BALD algorithm is superior to that of the RS algorithm. Indeed, the BALD algorithm achieves zero test error against the test errors 34.6% and 38.5% of the RS algorithm. Actually, as the amount of training images increases, the accuracy also increases. Interesting experiments could be executed in the future utilizing estimators from robust statistics inside the AL acquisition function framework. Up to now in the literature no other work has appeared to present deep AL on WorldView images for change detection. [ABSTRACT FROM AUTHOR]

Risk assessment constitutes the first part within the risk management framework and involves evaluating the importance of a risk, either quantitatively, or qualitatively. Risk assessment consists of three steps, namely risk identification, risk estimation and risk evaluation. Nevertheless, the risk management framework also includes a fourth step, i.e. the need for a feedback of all the risk assessment undertakings. However, there is a lack of such feedback, which constitutes a serious deficiency in the reduction of environmental hazards at the present time. Risk identification of local or regional hazards involves hazard quantification, event monitoring including early warning systems and statistical inference. Risk identification also involves the development of a database, where historical hazard information and their effects is included. Similarly, risk estimation involves magnitude/frequency relationships and hazard economic costs. Furthermore, risk evaluation consists of the social consequences of the derived risk and involves cost-benefit analysis and community policy. The objective of this review paper is twofold: On one hand, to address meteorological hazards and extremes within the risk management framework. Analyses results and case studies over Mediterranean ecosystems with emphasis on the wider area of Greece, in the eastern Mediterranean, are presented for each of the three steps of risk assessment for several environmental hazards. The results indicate that the risk management framework constitutes an integrated approach for environmental planning and decision making. On the other hand, it shed light to advances and current trends in the considered meteorological and environmental hazards and extreme events, such as tornadoes, waterspouts, hailstorms, heat waves, droughts, floods, heavy convective precipitation, landslides and wildfires, using recorded datasets, model simulations and innovative methodologies. [ABSTRACT FROM AUTHOR]

The element mercury (Hg) is a key pollutant, and much insight has been gained by studying the present-day Hg cycle. However, many important processes within this cycle operate on timescales responsive to centennial- to millennial-scale environmental variability, highlighting the importance of also investigating the longer-term Hg records in sedimentary archives. To this end, we here explore the timing, magnitude, and expression of Hg signals retained in sediments over the past ∼ 90 kyr from two lakes, linked by a subterranean karst system: Lake Prespa (Greece, North Macedonia, and Albania) and Lake Ohrid (North Macedonia and Albania). Results suggest that Hg fluctuations are largely independent of variability in common host phases in each lake, and the recorded sedimentary Hg signals show distinct differences first during the Late Pleistocene (Marine Isotope Stages 2–5). The Hg signals in Lake Prespa sediments highlight an abrupt, short-lived peak in Hg accumulation coinciding with local deglaciation. In contrast, Lake Ohrid shows a broader interval with enhanced Hg accumulation and, superimposed, a series of low-amplitude oscillations in Hg concentration peaking during the Last Glacial Maximum, which may result from elevated clastic inputs. Divergent Hg signals are also recorded during the Early and Middle Holocene (Marine Isotope Stage 1). Here, Lake Prespa sediments show a series of large Hg peaks, while Lake Ohrid sediments show a progression to lower Hg values. Since ∼ 3 ka , anthropogenic influences overwhelm local fluxes in both lakes. The lack of coherence in Hg accumulation between the two lakes suggests that, in the absence of an exceptional perturbation, local differences in sediment composition, lake structure, Hg sources, and water balance all influence the local Hg cycle and determine the extent to which Hg signals reflect local- or global-scale environmental changes. [ABSTRACT FROM AUTHOR]

Extensive continuous particle number size distribution measurements took place during two summers (2020 and 2021) at 11 sites in Greece for the investigation of the frequency and the spatial extent of new particle formation (NPF). The study area is characterized by high solar intensity and fast photochemistry and has moderate to low fine particulate matter levels during the summer. The average PM 2.5 levels were relatively uniform across the examined sites. The NPF frequency during summer varied from close to zero in the southwestern parts of Greece to more than 60 % in the northern, central, and eastern regions. The mean particle growth rate for each station varied between 3.4 and 8 nm h -1 , with an average rate of 5.7 nm h -1. At most of the sites there was no statistical difference in the condensation sink between NPF event and non-event days, while lower relative humidity was observed during the events. The high-NPF-frequency sites in the north and northeast were in close proximity to both coal-fired power plants (high emissions of SO 2) and agricultural areas with some of the highest ammonia emissions in the country. The southern and western parts of Greece, where NPF was infrequent, were characterized by low ammonia emissions, while moderate levels of sulfuric acid were estimated (10 7 molec. cm -3) in the west. Although the emissions of biogenic volatile organic compounds were higher in western and southern sectors, they did not appear to lead to enhanced frequency of NPF. The infrequent events at these sites occurred when the air masses had spent a few hours over areas with agricultural activities and thus elevated ammonia emissions. Air masses arriving at the sites directly from the sea were not connected with atmospheric NPF. These results support the hypothesis that ammonia and/or amines limit new particle formation in the study area. [ABSTRACT FROM AUTHOR]

The paper presents the kinematics of rock instability of a high limestone promontory, where the Monemvasia historical site is situated, in Peloponnese in Southern Greece. The instability phenomena poses a significant threat to the town located at the base of the slope. Rockfall episodes occurred in the past due to the relaxation of the high cliff, whereas significant undermining of the castle frontiers has been observed at the slope crest. The predominant types of instability are of planar, wedge and toppling failure of medium to large blocks. In order to investigate the existing stability conditions and decide upon the protection measures, stability and rockfall analyses were carried out for numerous slope sections under different loading conditions and protection measures were suggested. A rock-fall risk rating system is proposed, which is based on morphological and structural criteria of the rock mass and on vulnerability and consequences. The rating system is applied for individual sections along the slope and a risk map was produced, which depicted areas having different degree of risk against rockfall occurrences. [ABSTRACT FROM AUTHOR]

In this paper we show, in terms of Fisher information and approximate entropy, that the two strong impulsive kHz electromagnetic (EM) bursts recorded prior to the Athens earthquake (EQ) (7 September 1999, magnitude 5.9) present compatibility with the radar interferometry data and the seismic data analysis, which indicates that two fault segments were activated during Athens EQ. The calculated Fisher information and approximate entropy content ratios closely follow the radar interferometry result that the main fault segment was responsible for 80% of the total energy released, while the secondary fault segment for the remaining 20 %. This experimental finding, which appears for the first time in the literature, further enhances the hypothesis for the seismogenic origin of the analyzed kHz EM bursts. [ABSTRACT FROM AUTHOR]

In this paper we suggest the use of diffusion-neural-networks, (neural networks with intrinsic fuzzy logic abilities) to assess the relationship between isoseismal area and earthquake magnitude for the region of Greece. It is of particular importance to study historical earthquakes for which we often have macroseismic information in the form of isoseisms but it is statistically incomplete to assess magnitudes from an isoseismal area or to train conventional artificial neural networks for magnitude estimation. Fuzzy relationships are developed and used to train a feed forward neural network with a back propagation algorithm to obtain the final relationships. Seismic intensity data from 24 earthquakes in Greece have been used. Special attention is being paid to the incompleteness and contradictory patterns in scanty historical earthquake records. The results show that the proposed processing model is very effective, better than applying classical artificial neural networks since the magnitude macroseismic intensity target function has a strong nonlinearity and in most cases the macroseismic datasets are very small. [ABSTRACT FROM AUTHOR]

In the last decade 3D datasets of the Cultural Heritage field have become extremely rich and high detailed due to the evolution of the technologies they derive from. However, their online deployment, both for scientific and general public purposes is usually deficient in user interaction and multimedia integration. A single solution that efficiently addresses these issues is presented in this paper. The developed framework provides an interactive and lightweight visualization of high-resolution 3D models in a web browser. It is based on 3D Heritage Online Presenter (3DHOP) and Three.js library, implemented on top of WebGL API. 3DHOP capabilities are fully exploited and enhanced with new, high level functionalities. The approach is especially suited to complex geometry and it is adapted to archaeological and architectural environments. Thus, the multi-dimensional documentation of the archaeological site of Meteora, in central Greece is chosen as the case study. Various navigation paradigms are implemented and the data structure is enriched with the incorporation of multiple 3D model viewers. Furthermore, a metadata repository, comprises ortho-images, photographic documentation, video and text, is accessed straight forward through the inspection of the main 3D scene of Meteora by a system of interconnections. [ABSTRACT FROM AUTHOR]

This paper presents the development of a non-parametric forecast model based on artificial neural networks for the direct assessment of Arias Intensity corresponding to a historic earthquake using seismic intensity data. The neural models allow complex and nonlinear behaviour to be tracked. Application of this methodology on earthquakes with known instrumental data from Greece, showed that the artificial neural network forecast model have excellent data synthesis capability. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of the exceptionally high maximum(Tmax) and minimum(Tmin) temperatures which occurred during November 2010 and affected the entire Greek region. This severe "arm cold-season spell" was unusual because of its prolonged duration and intensity for the entire month and particularly the maximum temperature anomalies, which in comparison with the 1958--2000 climatological average, exceeded 5 °C at several stations. Comparing the observed record with future projections from three regional climate models revealed that Tmax and Tmin, on several days in November 2010, exceeded the 90th percentile of the simulated data. An examination of the atmospheric -- synoptic conditions during this period showed that the anomalous high temperatures could probably be related to the negative phase of the Eastern Mediterranean Pattern (EMP), with an intense pole of negative anomalies located over the British Isles, and to the east, a second pole of positive anomalies, centred over the Caspian Sea. Finally, an attempt is made to further investigate the mechanisms responsible for this phenomenon, for example, the thermal forcing in the tropics (Niño 3 or Niñno 3.4). [ABSTRACT FROM AUTHOR]

In this paper we examined whether the recorded precipitation changes cause erosion in Naxos Island, Greece using precipitation indices derived from daily precipitation totals, during the period 1955-2007, in order to develop an erosion risk model. Although the mean annual precipitation appear to be low (∼360.0mm), the erosion processes of the area are very intense, because of the intensive character of precipitation, the high slope relief, the differential lithology and the absence of important land cover The results of the analysis showed that the climatic changes in precipitation and the changes in land cover and land use are the main drivers for the erosion. This is why the 2nd (1971-1985) and 3rd (1986-2007) studied sub-periods may be called of high erosion risk, and especially the second one mainly because of the increased frequency of extreme precipitation events. [ABSTRACT FROM AUTHOR]

In the framework of this paper, one-year of lightning data from the experimental network ZEUS operated by the National Observatory of Athens is compared to collocated data provided by the LINET detection network. The area of comparison is limited to a part of Central-Western Europe, where LINET data exhibits the highest data quality, permitting thus to be used as the validation dataset. The location error of ZEUS was calculated to be ∼6.8 km, while the detection efficiency was ∼25%, with a characteristic underdetection during nighttime. Moreover, the analysis revealed that ZEUS is also capable to detect not only cloud-to-ground but also intra-cloud strokes. Analysis of a specific case study revealed that the spatial distribution of ZEUS was very close to that of LINET, although the total number of strokes as seen by ZEUS is much lower than the one from LINET. The overall analysis permitted to assess the main characteristics of ZEUS network, information considered of paramount importance before the use of ZEUS data for a variety of observational and modeling work. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the performance of the Infrared Atmospheric Sounding Interferometer (IASI), launched in October 2006 on board METOP-A, for the monitoring of carbon monoxide (CO) during extreme fire events, focusing on the record-breaking fires which devastated thousands of square kilometers of forest in Greece during the last week (23-30) of August 2007. After an assessment of the quality of the profiles retrieved using the Fast Optimal Retrievals on Layers for IASI (FORLI) algorithm, the information provided on fire emissions and subsequent pollution outflow is discussed. Large CO plumes were observed above the Mediterranean Basin and North Africa, with total CO columns exceeding 24 × 1018 molecules/cm² and absolute volume mixing ratios up to 4 ppmv on the 25 August. Up to 30 × 1018 molecules/cm² and 22 ppmv in the lower troposphere are retrieved close to the fires above the Peloponnese, but with larger uncertainty. The average root-mean-square (RMS) difference between simulated and observed spectra is close to the estimated radiometric noise level, slightly increasing (by ∼14%) in the fresh fire plumes. CO pro- files are retrieved with a vertical resolution of about 8 km, with ∼1.7 pieces of independent information on the vertical in the region considered and a maximum sensitivity in the free troposphere (∼4-5 km). Using the integrated total amount, the increase in CO burden due to these fires is estimated to 0.321 Tg, ∼40% of the total annual anthropogenic emissions in Greece. The patterns of these CO enhancements are in good agreement with the aerosol optical depth (AOD) retrieved from the MODIS measurements, highlighting a rapid transport of trace gases and aerosols across the Mediterranean Basin (less than one day). While the coarse vertical resolution will not allow the location of the exact plume height, the large CO enhancements observed in the lower troposphere are consistent with the maximum aerosol backscatter coefficient at ∼2 km detected by the CALIPSO lidar in space (CALIOP). [ABSTRACT FROM AUTHOR]

Ionospheric variability as a result of earthquake events is a confirmed phenomenon as published in various seismo-ionospheric coupling studies. Generally, ionospheric variations resulting from earthquake activity are much weaker than disturbances generated by different sources, e.g. geomagnetic storms. However, geomagnetic storm disturbances exhibit more global behaviour, whereas seismo-ionospheric variations occur only locally in an area that is specified by the magnitude of the earthquake. Cross-correlation coefficient analysis is a technique proposed some years ago, and ensures cancelation of geomagnetic storm variations of the ionospheric plasma, provided that the measurements are taken from stations with similar behaviour in these phenomena. In this paper we will use the aforementioned technique for analyzing data from ionospheric stations in Rome and Athens, and apply it to a series of earthquakes in Greece. Considering the local behaviour of the seismoionospheric variations, we expect that the Athens station, which happens to be inside the area affected by the earthquake, will accurately capture the disturbances. Due to its distance from the activity, we also do not expect the Rome station measurements to be affected by the seismic events in Greece. In addition, due to the fact that ionospheric plasma parameters exhibit non-stationary and nonlinear behaviour, we propose a novel signal processing technique known as the Hilbert-Huang transform in order to denoise the data before we calculate the cross-correlation coefficient of the two signals. Results from our analysis are in accordance with previously-conducted studies covering the same topic, clearly demonstrating that there are ionospheric precursors 1 to 7 days prior to strong seismic events as well as 1 to 2 days following such events. [ABSTRACT FROM AUTHOR]