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Στα πλαίσια του ερευνητικού προγράμματος Interreg ΘΑΛ-ΧΩΡ 2, με τη συνδυασμένη χρήση μετεωρολογικών μετρήσεων σε όλο το νησί, προγνώσεων του ανέμου από μετεωρολογικά μοντέλα υψηλής ανάλυσης, και στοιχείων από δύο ευρωπαϊκές βάσεις μετεωρολογικών δεδομένων, δημιουργήθηκε βάση δεδομένων για την αποτύπωση μιας όσο το δυνατόν πιο αξιόπιστης εικόνας της χωρικής και χρονικής κατανομής του θαλάσσιου αιολικού δυναμικού, σε ετήσια και σε εποχική βάση. Η αποτυπωμένη πληροφορία αναλύθηκε, συνδυάστηκε και έγινε επέκτασή της σε υψηλότερη ανάλυση 1x1 km, σε ωριαία βάση, για ορίζοντα δεκαετίας. Τα αποτελέσματα κωδικοποιήθηκαν σε εύχρηστη πλατφόρμα Excel, η οποία μπορεί να δοθεί σε οποιονδήποτε ενδιαφερόμενο χρήστη για να εκτιμήσει το αιολικό δυναμικό σε οποιοδήποτε σημείο της Κύπρου, καθώς και της παράκτιας περιοχής της, με αυτόματη παρεμβολή μεταξύ των εκτιμήσεων. Η πλατφόρμα επιτρέπει την εξαγωγή ολικής εικόνας για τον άνεμο στην περιοχή της Κύπρου και, εκτός από τη χωρική εστίαση, δίνει τη δυνατότητα χρονικής επιλογής οποιασδήποτε περιόδου συγκεκριμένων διαστημάτων ωρών, μηνών και ετών, για την περίοδο 2008-2019. Επίσης, αποδίδονται στατιστικές πληροφορίες για τη μέση, μέγιστη, ελάχιστη τιμή, τη διακύμανση της ταχύτητας, καθώς και για τους συντελεστές της κατανομής Weibull. Παράλληλα, παρατίθενται αυτόματα και πληροφορίες για την ημερήσια, μηνιαία και ετήσια κατανομή της ταχύτητας, όπως και οι κατανομές Weibull. Σε μελλοντικό χρόνο, οι παραπάνω δυνατότητες θα προσφέρονται και διαδικτυακά.

While velocity differences in turbulence have attracted much interest, velocity fluctuations themselves are also fundamental in describing turbulence. Even though there is a large literature on the non-Gaussian nature of the probability density functions (PDFs) of the turbulent velocity gradients, the PDFs of the velocity fluctuations in homogeneous turbulence is often assumed to be Gaussian. In fact, many experiments yield a sub-Gaussian PDF, which has a less pronounced tail than a Gaussian PDF. Systematic examination of grid turbulence has shown that at small distances from the grid, where the turbulence is still developing, the PDF is sub-Gaussian. At intermediate distances, where the turbulence is fully developed, the PDF is Gaussian. At large distances, where the turbulence decays, the PDF is hyper-Gaussian. Turbulence is induced by supplying kinetic energy at some scale L. This energy could be transferred to both the larger and the smaller scales. However, the energy is on average transferred to smaller scales because it is eventually dissipated into heat at the smallest scales, described by the Kolmogorov length η. The energy transfer from largest scales L to smallest scales η consists of many random steps, each of which occurs preferentially between neighboring scales. Τurbulence exhibits significant velocity fluctuations even at scales much larger than the scales of the energy supply. These large-scale fluctuations have many degrees of freedom and are thereby analogous to thermal fluctuations studied in the statistical mechanics. We perform Direct Numerical Simulations (DNS) in the presence of homogenous isotropic turbulence to show that the deviation from the Gaussian behavior is a natural consequence of the steepness of the energy spectrum, and of the properties of the energy-containing eddies. A clear dependence is observed based on the ratio of the integral length varies as a function of the periodic-box size for different Reynolds numbers.

ROMS-AGRIF (Regional Ocean Model System, Adaptative Mesh Refinement In Fortran) is a free surface numerical ocean model that solves the primitive equation with the Boussinesq approximation with respect to hydrostatic vertical momentum balance. The model uses terrain-following vertical coordinates that allow differential stretching, within orthogonal, curvilinear, spherical horizontal coordinates. Equations are solved with short time steps for barotropic dynamic (ssh and 2D momentum) and a much larger time steps for baroclinic dynamic (T, S, 3D momentum) in a split explicit scheme. It uses rotated tensors to reduce diapycnal mixing and improved calculation of horizontal pressure gradient, following surface and bottom KPP turbulent closure model, thus obtaining high advection scheme. It uses adaptive mixed radiations/nudging open boundary conditions and it uses parallelization by two …

The aim of this paper is to present our strategy and vision to upgrade the existing ERATOSTHENES Research Centre (ERC), established within Cyprus University of Technology (CUT), into a sustainable, viable and autonomous Centre of Excellence (CoE) for Earth Surveillance and Space-Based Monitoring of the Environment (EXCELSIOR), which will provide the highest quality of related services both on the National, European and International levels. The ‘EXCELSIOR’ project is a Horizon 2020 Teaming project, addressing the reduction of substantial disparities in the European Union by supporting research and innovation activities and systems in low performing countries. It also aims at establishing long-term and strategic partnerships between the Teaming partners, thus reducing internal research and innovation disparities within European Research and Innovation landscape. The ERCis already an established player in the local community and has excellent active collaboration with actors from various sectors in (a) the government, (b) industry, (c) local organisations, and (d) society. In order to further engage users and citizens and to become more attractive to international research and education community, the Centre aims to be fully involved in strategic positioning on the national level, but also in Europe, the Middle East region and internationally. Some examples of how space technologies are integrated with other tools or techniques such as UAV, field spectroscopy, micro-sensors, EO space/in-situ sensors etc. for the systematic monitoring of the environment is shown. Indeed such examples fulfills the objectives of the COPERNICUS academy network (in which ERC is a member) for empowering the next generation of researchers, scientists, and entrepreneurs with suitable skill sets to use Copernicus data and information services to their full potential. Finally, opportunities for future collaboration and investments with the ERC in the Eastern Mediterranean Region are stated. Five partners have united to upgrade the existing ERC into a CoE, with the common vision to become a world-class innovation, research and education centre, actively contributing to the European Research Area (ERA). More specifically, the Teaming project is a team effort between the Cyprus University of Technology (CUT, acting as the coordinator), the German Aerospace Centre (DLR), the Institute for Astronomy and Astrophysics Space Applications and Remote Sensing of the National Observatory of Athens (NOA), the German Leibniz Institute for Tropospheric Research (TROPOS) and the Cyprus’ Department of Electronic Communications of the Ministry of Transport, Communications and Works (DEC-MTCW).

Using Data INterpolating Empirical Orthogonal Functions (DINEOF) Algorithm for filling the missing data of AVHHR satellite images. Andreas Nikolaidis(*,a,b), Stavros Stylianou(b,Georgios Georgiou(b), Diofantos Hajimitsis(a) and Evangelos Akylas(a) a. Department of Civil Engineering and Geomatics, Cyprus University of Technology, 30 Archbishop Kyprianou Str., 3036, Limassol, Cyprus b. University of Cyprus, PO BOX 20537, 1678, Nicosia, Cyprus, Oceanography Centre KEY WORDS: Remote Sensing, Cyprus, Mediterranean, DINEOF, ArcGIS, data reconstruction. During the last decade, Rixen (2005) and Alvera-Azkarate (2010) presented the DINEOF (Data Interpolating Empirical Orthogonal Functions) method, a EOF-based technique to reconstruct missing data in satellite images. The application of DINEOF method, proved to provide relative success in various experimental trials (Wang and Liu, 2013; Nikolaidis et al., 2013;2014), and tends to be an effective and computationally affordable solution, on the problem of data reconstruction, for missing data from geophysical fields, such as chlorophyll-a, sea surface temperatures or salinities and geophysical fields derived from satellite data. Implementation of this method in a GIS system will provide with a more complete, integrated approach, permitting the expansion of the applicability over various aspects. This may be especially useful in studies where various data of different kind, have to be examined. For this purpose, in this study we have implemented and present a new GIS toolbox that aims to automate the usage of the algorithm, incorporating the DINEOF codes provided by GHER (GeoHydrodynamics and Environment Research Group of University of Liege) into the ArcGIS®. ArcGIS® is a well known standard on Geographical Information Systems, used over the years for various remote sensing procedures, in sea and land environment alike. A case-study of filling the chlorophyll-a missing data in the Mediterranean Sea area, for a 18-day period is analyzed, as an example for the effectiveness and simplicity of the usage of this toolbox. The specific study focuses to chlorophyll-a MODIS satellite data collected by CNR-ISAC (Italian National Research Council, Institute of Atmospheric Sciences and Climate), from the respective products of MyOcean2® organization, that provides free online access to Level 3, with 1 km resolution. In particular, all the daily products with an initial level of only 27% data coverage were successfully reconstructed.

Nuclear fusion energy faces many challenges concerning maximizing the potential output of energy and making it an efficient way of energy transfer into usable in our everyday lives. In a fusion reaction, the mass of products is smaller than the mass of its reactants. This difference is converted into energy, having a tremendous amount of energy, according to Einstein's equation E=mc². Requirements for fusion here on earth are challenging to obtain because of the energy barrier of electrostatic forces, which must be overcome to accomplish the main objective. Three main conditions are required for a controlled fusion energy reactor: high temperature, high pressure, and controllable magnetic confinement. The temperature must be hot enough (around 100 million Kelvin) for deuterium and tritium ions to overcome the Coulomb barrier by having the necessary kinetic energy and fuse together. In this state, plasma transition occurs which all the electrons are stripped from the hydrogen atoms and move freely around fully ionized. High pressure is the main requirement because for the hydrogen atoms to be fused, they must be at an incredibly small distance together, and pressure alternation makes this possible along with the high temperature. This heating and pressure empowerment in a reactor core need to be controlled as the conditions happening could not be withstander by any means of earth materials. When the gas turns into plasma, magnetic confinement made by superconducting magnets gets pressed, allowing for fusion to occur; therefore, these requirements and conditions for fusion energy to happen to bring many challenges to the structural materials to withstand the terms of such state. Structural elements and functional materials must have the radiation resistance and the required level of integrity, respectively. This case study focuses on a preliminary design for a fusion reactor's helium-cooled, solid breeder coolant. The aim and objectives are given and the project approach to gain a deeper understanding of how everything was monitored. A literature review is given, a brief history of time in nuclear fusion reactors, and examples of existing technology, including tokamaks. Information about tritium and tritium breeding blankets is also included. The design work was mainly focused on neutronic, thermal aspects using a helium coolant. Completed

Η Επιχειρησιακή Ωκεανογραφία είναι ένας από τους πιο ενδιαφέροντες κλάδους της επιστήμης της Ωκεανογραφίας, σχετικά νέα και ταχέως αναπτυσσόμενη τις τελευταίες δεκαετίες, με την αριθμητική μοντελοποίηση ως ένα από τα πιο σημαντικά, συναρπαστικά και ανταγωνιστικά προϊόντα της. Σημαντικός αριθμός αριθμητικών μοντέλων έχουν αναπτυχθεί προκειμένου να αντισταθμιστούν οι δυσκολίες συλλογής in-situ δεδομένων και εξελίσσονται συνεχώς με τη βοήθεια των βελτιώσεων της τεχνολογίας στους τομείς των υπολογιστών και των δορυφόρων. Ωστόσο, μεταξύ των πολλών από τις απαιτούμενες βελτιώσεις ξεχωρίζουν δύο, μεγάλης σημασίας: * εναλλακτικές αριθμητικές προσομοιώσεις, και συγκεκριμένα, ωκεανογραφικές προσομοιώσεις της θαλάσσιας δυναμικής της κυκλοφορίας της ανατολικής Μεσογείου και ιδιαίτερα της θάλασσας της Λεβαντίνης. Αναμενόμενη πρόοδος σε αυτά τα είδη μοντέλων είναι η υψηλότερη λεπτομέρεια και ακρίβεια αποτελεσμάτων. Παρά το γεγονός ότι τέτοια μοντέλα έχουν υιοθετηθεί αποτελεσματικά σε διάφορα μέρη του πλανήτη, δεν έχει εφαρμοστεί ποτέ μέχρι τώρα, στη συγκεκριμένη περιοχή της Λεβαντίνης. * δεδομένα και αριθμητικές μέθοδοι που να βελτιώνουν δορυφορικά προϊόντα, όπως το ύψος επιφάνειας της θάλασσας, οι τιμές θερμοκρασίας, αλατότητας και χλωροφύλλης-α. Ειδικοί αλγόριθμοι, όπως το DINEOF, χρησιμοποιούνται για την συμπλήρωση δεδομένων που λείπουν, που προκαλούνται από αιτίες όπως η νέφωση, και έτσι να εμπλουτίσουν τις πληροφορίες που θα χρησιμοποιηθούν από τα αριθμητικά μοντέλα. Αυτός ο αλγόριθμος, που παρουσιάζεται στην παρούσα εργασία, εφαρμόζεται για πρώτη φορά σε δορυφορικά δεδομένα στην Ανατολική Μεσόγειο. Η παρούσα διατριβή επιχειρεί επιπλέον παρουσίαση των ιδιαίτερων συστατικών που περιγράφουν την ανάπτυξη, προσαρμογή και εφαρμογή ενός νέου αριθμητικού μοντέλου θαλάσσιας δυναμικής. Αρχικά παρουσιάζεται μια περιγραφή της γενικής κυκλοφορίας των ωκεανών, με αναφορά σε μηχανισμούς και συναφείς θεωρίες. Έμφαση δίνεται στην περιγραφή των θεμελιωδών φυσικών αρχών που διέπουν την ανεμογενή γενική θερμόαλη κυκλοφορία του πλανήτη. Παρουσιάζεται η φυσιογραφία της Μεσογείου και οι επικρατούσες απόψεις της υφιστάμενης κυκλοφορίας που επικρατεί. Τέλος, γίνεται αναφορά στην επίδραση διαφόρων μετεωρολογικών συνθηκών σε φαινόμενα μέσης και μικρότερης κλίμακας, με ιδιαίτερη αναφορά στην ανατολική Μεσόγειο και την ευρύτερη περιοχή της Λεβαντίνης, με επίκεντρο την περιοχή γύρω από την Κύπρο. Operational Oceanography is one of the most interesting branches of the science of Oceanography, relatively new and under rapid development during the last decades, with numerical modeling as one of the most important, fascinating and challenging products. A number of numerical models have been developed in order to anticipate the difficulties in gathering in-situ data and they are evolving continuously with the aid of the technological improvements in the fields of computers and of satellites. However, among the many required improvements there are two of great importance: • alternative numerical oceanographic, and specifically, marine dynamics simulations of the circulation of the eastern Mediterranean and particularly of the Levantine Sea. The expected advance with this kind of model is higher and more accurate details in the obtained results. While such a model has been adopted effectively in various places of the globe, it has never been applied over the specific area of Levantine so far. • data and numerical methods that should improve the satellite products, such sea surface height, temperature, salinity and chlorophyll-a. Application algorithms, like DINEOF, are used to eliminate missing data caused by cloud interference and thus to enrich the information that will drive the numerical models. This algorithm is applied for the first time to satellite data over the Eastern Mediterranean. This thesis attempts a presentation on the particular features that describe the devel- opment and implementation of a new marine dynamics numerical model. Initially there is a description of the general ocean circulation, with reference to mechanisms and related theories. Emphasis is given on the description of the basic physical principles and on the general wind generated and thermohaline circulation in the planet. A summary of the Mediterranean physiography and the prevailing opinions of the emerging circulation will be shown. Finally, reference is made to the effect of different meteorological conditions on submeso-scale phenomena, with particular reference to the eastern Mediterranean and Levantine region, focusing on the area around Cyprus. Completed

The Boussinesq equation is a dynamical equation for the free surface of saturated subsurface flows over an impervious bed. Boussinesq equation is non-linear. The non-linearity comes from the reduction of the dimensionality of the problem: The flow is assumed to be vertically homogeneous, therefore the flow rate through a cross section of the flow is proportional to the free surface height times the hydraulic gradient, which is assumed to be equal to the slope of the free surface, (Dupuit, 1863). In general, ‘vertically’ means normally on the bed; combining the Dupuit approximation with the continuity equation leads to the Boussinesq equation (Boussinesq, 1877). There are very few transient exact solutions. For the confined flow case for zero recharge rate Boussinesq derived for the horizontal aquifer an exact solution assuming separation of variables, (Boussinesq (1904), Polubarinova-Kochina (1962)). This is actually an exact asymptotic solution of the horizontal aquifer recession phase for late times. The kinematic wave, (Boussinesq (1877), Lighthill and Witham (1955), Henderson and Wooding (1964), Beven (1981)), is an interesting solution obtained by dropping the non-linear term in the Boussinesq equation. Although it is an approximate solution, and holds well only for small values of the Henderson and Wooding λ parameter (that is, for steep slopes, high conductivity or small recharge rate), it becomes less and less approximate for smaller values of the parameter, that is, it is asymptotically exact with respect to that parameter. In the present work we consider the case of the confined subsurface flow over horizontal bed in the build-up phase under constant recharge rate. This is a case with an infinite Henderson and Wooding parameter, that is, it is the limiting case where the non-linear term is present in the Boussinesq while the linear spatial derivative term goes away. Nonetheless, no analogue of the kinematic wave or the Boussinesq separable solution exists in this case. The late time state of the build-up phase under constant recharge rate is very simply the steady state solution. Our aim here is to construct an accurate approximate solution for the built-up phase which clarifies the physical response of the aquifer to the uniform constant recharge. Στην εργασία αυτή επικεντρωθήκαμε στη μελέτη και κατασκευή μιας νέας προσεγγιστικής λύσης της εξίσωσης του Boussinesq για την περίπτωση του περιορισμένου οριζόντιου υδροφόρου ορίζοντα υπό συνθήκες ομοιόμορφης φόρτισης. Από την αριθμητική επίλυση της Boussinesq (3.5) γίνεται ότι σε μικρούς χρόνους (τ < 0.4) επικρατεί μία τάση γρήγορης αλλαγής του προφίλ, το οποίο εξελίσσεται με μορφή κατά προσέγγιση μεταβλητού τραπεζίου του οποίου το ύψος αυξάνεται γραμμικά με το χρόνο. Σε μεταγενέστερους χρόνους (τ > 0.4), το προφίλ του νερού στον οριζόντιο υδροφορέα παίρνει ένα σχετικά σταθερό παραβολικό σχήμα (πλησιάζει σε steady-state). Σε αυτό το στάδιο οποιαδήποτε έννοια γραμμικότητας στην εξέλιξη με το χρόνο έχει χαθεί. Σε κάθε περίπτωση όμως διαφαίνεται ένας σαφής διαχωρισμός της εξέλιξης του προφίλ σε μικρούς χρόνους, μικρότερους του 0.4, και μεγαλύτερους από το 0.4 χρόνους, συμπέρασμα το οποίο αποτελεί και την κεντρική ιδέα και έμπνευση για μία πιο αποτελεσματική και περιγραφική πρωτότυπη προσέγγιση του προβλήματος με μία νέα πρωτότυπη μέθοδο. Η νέα μέθοδος βασίζεται σε μια εξειδικευμένη εικασία «ansatz» του προφίλ του νερού στον υδροφορέα για κάθε φάση του, που αφήνει ορισμένες λειτουργίες του χρόνου ως βαθμούς ελευθερίας για να καθοριστεί έτσι δυναμικά μέσα από τη μη γραμμική διαφορική εξίσωση η εξέλιξη τους. Οι προκύπτουσες συνθήκες μπορούν να λυθούν με ακρίβεια έτσι που να οδηγούν σε προσεγγιστικές λύσεις οι οποίες είναι σαφείς και απλές. Οι λύσεις των δύο φάσεων σε σύγκριση με τις αντίστοιχες αριθμητικές λύσεις της εξίσωσης Boussinesq δείχνουν μάλλον πως συμφωνούν εντυπωσιακά αποδίδοντας ποιοτικά και ποσοτικά τα χαρακτηριστικά της πλήρους εξίσωσης Η μη γραμμικότητα στην εξέλιξη του προβλήματος έχει και σε χρονικούς και σε χωρικούς όρους και σε κάθε στιγμιότυπο είναι πολύ ακριβέστερη από παλαιότερες προσεγγιστικές γραμμικές λύσεις Σε κάθε περίπτωση η ξεκάθαρη αναλυτική περιγραφή και η ακρίβεια της προσέγγισης θεωρούμε ότι αποδίδει ευκρινώς τη φυσική της εξέλιξης και αποτελεί ένα μικρό βήμα στην κατανόηση του φαινομένου. Completed

Isotropic turbulence is an ideal state where the motion properties, in the statistical sense, do not show any directional dependence. More strictly, they satisfy rotational and translational invariance. Isotropic turbulence is the simplest form of turbulent flow still maintaining all its fundamental characteristics. It has been the playground for theoretical work through the last century. Isotropy as a statistical notion is not manifest at the level of the velocity field dynamics but at the level of the correlation functions, where the averaging has removed all the irrelevant direction dependencies. Isotropic turbulence lives strictly in an infinite physical space. Via this energy cascade, turbulent flow can be realized as a superposition of a spectrum of flow velocity fluctuations and eddies upon a mean flow. The eddies are loosely defined as coherent patterns of flow velocity, vorticity and pressure. However, the isotropic flow, requiring first of all an infinite physical space to live in, is an idealization that cannot be strictly realized even in the clinical environment of numerical simulations. In the direct numerical simulations (DNS) of isotropic turbulence one usually solves the Navier-Stokes equation imposing periodicity. The idea is to introduce finiteness in space in a smooth manner. Isotropic flows are replaced by another kind of ideal flows that can be handled numerically. In the infinite space the infinite sequence of equations has to be closed at some finite order, this is being done semi-empirically. In other words, we must truncate this set of equations by a model, each reasonable model is called a closure model. The Eddy Damped Quasi-Normal Markovian (EDQNM) is a subfilter closure model applied in spectral wavenumber space rather than physical space which considers interactions between resolved and subfilter wavenumbers by considering the statistics of their possible interactions. The EDQNM achieves closure by modeling the 4th spectral moments. An EDQNM code for resolving forced isotropic turbulence was created in this work. The work may be considered as continuation of previous work done by Michalis Pieris (2016) who wrote an EDQNM code for equally distant wave-numbers, however permitting the possibility of resolving large Reynolds numbers. The new code was applied in the case of for forced turbulence at Reynolds number around 1000, resembling high Reynolds DNS from the past. The comparison shows significant similarities in the macroscopic characteristics of the stationary state, however, it reveals a different behavior at the dissipative range with sharper tails and lower palinstrophy values at the EDQNM spectra. Completed