D. N. Asimakopoulos

• PhD
• Professor Emeritus at National and Kapodistrian University of Athens

COVID-19 is evolving into one of the worst pandemics in recent history. The lockdown measures implemented worldwide to slow the spread of the COVID-19 pandemic have caused an unprecedented reduction in global economic activity. Strict lockdown measures came into force in Greece from March 23th 2020. This study aims to assess the changes in air poll...

Contaminants of biological origin, such as fungi and bacteria, are ubiquitous inside the residences and especially in bedroom microenvironments. Epidemiological studies have shown that fungal exposure is associated with respiratory and allergic symptoms. Infants and young children comprise a susceptible population to study, since they spend most of...

With the principal aim to assess the typical Mediterranean profile of the PM2.5 and PM1 pollution, three intensive monitoring campaigns took place simultaneously within different types of environment across an urban location of the basin. Focusing on the PM components with numerous anthropogenic sources and increased potential health risk, the samp...

Nowadays, the advancement of mobile technology in conjunction with the introduction of the concept of exposome has provided new dynamics to the exposure studies. Since the addressing of health outcomes related to environmental stressors is crucial, the improvement of exposure assessment methodology is of paramount importance. Towards this aim, a pi...

Linking synoptic circulation patterns to specific environmental problems is of significance in the Eastern Mediterranean region, which is characterized by increased seasonal climatic variability and a wealth of distinct weather patterns. This study aims to discuss the links between synoptic scale circulation, intra-day variability and sub-hourly te...

Nowadays, the modern way of human life has lead to an increasing exposure to residential indoor air pollution sources (i.e. building materials, solvents used in cleaning, paints, bio-contaminants, tobacco smoke, carpets and combustions) which has been associated with adverse health effects. Especially infants and young children comprise a vulnerabl...

Although the indoor thermal comfort concept has received increasing research attention, the vast majority of published work has been focused on the building environment, such as offices, residential and non-residential buildings. The present study aims to investigate the thermal comfort conditions in the unique and complex underground railway envir...

The Chernobyl nuclear accident is already well documented in respect to the technical details responsible for the event, as well as the emissions to the atmosphere. However what is of importance is to further discuss the lower and the upper atmosphere transport mechanisms that prevailed on both over the local and the long distance atmospheric envir...

Resilience and climate adaptability plans for the thermal environment at the urban scale describe the measures to control anthropogenic heat sources in view of reducing skin and air temperatures. Such plans are based either on field measurements and/or simulations to define the energy budget at the urban scale as well as of the energy exchange betw...

Dragon is a cooperation Programme between the European Space Agency (ESA) and the Ministry of Science and Technology (MOST) of the P.R. China. The Programme, initiated in 2004, focuses on the exploitation of ESA, Third Party Missions (TPM) and Chinese Earth Observation (EO) data for geo-science and applications development in land, ocean and atmosp...

The thermal environment in modern cities has become potentially unfavorable and harmful for its residents, as a result of urbanization and industrialization. Exposure to these extreme thermal conditions increases the heat stress of people in cities considerably. In this context, the present study aims to investigate the urban thermal environment of...

The objective of this work is the study of the spectral characteristics of the wind components in the surface Atmospheric Boundary Layer (ABL). The analyzed data are based on an experimental campaign measurements which has been conducted in the framework of the European project ECATS, at the Athens International Airport (AIA), Greece, from 13th to...

Geometric shapes of coherent structures such as ramp or cliff like signals, step changes and waves, are commonly observed in meteorological temporal series and dominate the turbulent energy and mass exchange between the atmospheric surface layer and the layers above, and also relate with low-dimensional chaotic systems. In this work a simple linear...

Thermal indices are important for assessing human thermal perception and are widely used as indicators of heat strain as well as for designing, tourism and forecast purposes. This research focuses on thermal sensation scales calibration of a large number of thermal indices in order to be applied with greater success in outdoor urban environments in...

Airborne particulate matter in the PM2.5 and PM1 size ranges has been sampled at three sites within the Mediterranean urban area of the Athens Basin, representing background, roadside-industrialized and coastal background locations. With the principal aim to identify the sources and discriminate the contribution of the regional input versus the loc...

Previous studies have shown that bioclimatic indices predictions differ from actual thermal sensation and that their predictability varies depending on the climate. This study aims to assess the potential of a large number of widely used bioclimatic indices to describe human thermal sensation as well as to identify the one that most successfully si...

Under the same urbanization pressure, the local climate in large metropolitan areas is also altered. This is especially apparent when certain climatic characteristics are considered, e.g. temperature, humidity and wind. In fact, all the main meteorological parameters are severely affected, resulting in the development of a local climatic regime, wh...

During the last decades, the Particulate Matter (PM) pollution has become one of most challenging environmental problems worldwide. Along with their impact on global climate change and ecosystems, particles, especially for the smaller one, are indicated by numerous epidemiological studies to pose a great risk to human health with acute or long-term...

A field questionnaire survey was carried out simultaneously with weather measurements, in three urban areas in Athens, Greece, focusing on individual thermal sensation and its relationship with the environment in Mediterranean climates. Moreover thermal acceptability by means of thermal sensation votes was assessed based on Universal Thermal Climat...

Urbanization and industrialization are the main causes of the well documented climatic phenomenon called heat island. As the problem is worse in big cities, more urban residents complain about discomfort conditions. In this context, the aim of the present study is a combinational approach of heat island and thermal bioclimate in the city of Athens....

Major sport events may result in the modification of the urban environment, or may be used as a tool for urban planning and/or urban regeneration projects. To this end, the main objective of the DRAGON-2 Project 5295 was to support the planning needs of major sport events with the use of Earth Observation (EO). The project also focused on the post...

Total ozone is closely connected with two crucial environmental problems: ozone depletion and global climate change. The Dobson spectrophotometer is the oldest measuring device (prototype) for total ozone observations in the atmosphere. The Dobson spectrophotometer No. 118 has been installed in Athens, Greece since 1989. We present a brief overview...

Hourly PM10, NOX and O3 samples were collected simultaneously, at a rural rapid developing area, the Mesogia Plain. The measurements took place both winter (10) and summer (10) days, at five different sites of the area, during the period of 2008. The influence of the synoptic and mesoscale circulation on the configuration of the obtained air pollut...

Measurements of both mass (PM10, PM2.5, PM 1) and number concentration of particles (diameter between 0.30 and 20 μm), were employed at a coastal background area of Athens during the summer period July-August 2008. The daily concentrations of PM10, PM2.5 and PM1 did not exceed 74.7μg/m3, 47.3μg/m3 and 32.0μg/m3, respectively while the maximum value...

Synoptic climatology relates the atmospheric circulation with the surface environment. The aim of this study is to examine the variability of the surface meteorological patterns, which are developing under different synoptic scale categories over a suburban area with complex topography. Multivariate Data Analysis techniques were performed to a data...

This work aims to study surface meteorological patterns under different synoptic scale categories. Multivariate Data Analysis techniques were applied on two datasets including surface meteorological elements, and meteorological variables in the lower troposphere (850 and 700 hPa). For the former, three principal components were found, related to th...

This research focuses on projecting the energy demand of the building sector in Greece by calculating energy consumption, using output data from regional climate models up to 2100. More specifically, Greece was subdivided into 13 climatic zones after assessing climate model data taking into account climate change estimates for the period 2010–2100....

Chapter 5 of the June 2011 report by Climate Change Impacts Study Committee, Bank of Greece. https://www.bankofgreece.gr/Publications/ClimateChange_FullReport_bm.pdf

In this study the performance of organic PCMs used as latent heat storage materials, when incorporated in coatings for buildings and urban fabric, is investigated. Thirty six coatings of six colors containing different quantities of PCMs in different melting points were produced. Accordingly, infrared reflective (cool) and common coatings with the...

The aim of this paper is to study the urban micro-climatic conditions in the historic centre of Tirana in order to integrate the information in the rehabilitation of specific open spaces. The process included field measurements of the thermal characteristics in the examined area, bioclimatic design and use of passive cooling techniques (cool materi...

Using ground-based spectral solar extinction data taken in the greater urban Athens atmosphere during a field survey, experimental and modeled aerosol optical depths have been retrieved. The Angstrom's turbidity parameters (a, β) were derived via three widely used techniques: the Volz, the logarithmic and the direct fitting methods to the experimen...

Urban Heat Island refers to the temperature increase in urban areas compared to rural settings, exacerbating the energy consumption of buildings for cooling. The use of highly reflective materials in buildings and urban structures reduces the absorbed solar radiation and contributes to mitigate heat island. This paper presents the results of a stud...

Full text here: https://www.bankofgreece.gr/Publications/Πληρης_Εκθεση.pdf?mode=preview

Parallel measurements of ambient particulate matter mass in terms of PM(10), PM(2.5) and PM(2.5-10), conducted during a 53 months long experiment, between 2003 and 2008. The data constituting one of the longest simultaneous comparative data sets for the three PM fractions in Europe, collected at a suburban area of Athens, Aghia Paraskevi. Total mea...

In this study, an updated and extended climatology of cyclonic tracks affecting the eastern Mediterranean region is presented, in order to better understand the Mediterranean climate and its changes. This climatology includes intermonthly variations, classification of tracks according to their origin domain, dynamic and ki-nematic characteristics,...

In the photosynthesis process, solar radiation energy is converted to chemical energy by using atmospheric CO2. That is, almost all living species depend on energy produced through photosynthesis for their nourishing components thus making photosynthesis vital to the earth's life. Nevertheless, the knowledge of photosynthetic photon flux density QP...

The objective of this study is to investigate the relationship of orography over Greece with prolonged dry spells, as represented by the maximum number consecutive dry days (CDD index) during an extremely dry summer. For this purpose a simulation experiment was conducted with the aid of the regional climate model RegCM3.1 using a spatial resolution...

The aim of the present study is to examine the variability of tropospheric ozone residual (TOR) over Athens, Greece. The investigation of the relationship between TOR variability and the variations of atmospheric parameters like tropopause height and outgoing longwave radiation is attempted. Wiener spectral analysis is applied in order to explore t...

The relationship of prolonged dry spells in Eastern Mediterranean with large-scale surface and upper circulation is investigated on seasonal basis with the aid of the Singular-Value Decomposition Analysis (SVDA) for the period 1958–2000. The study was based on daily precipitation data of 56 stations, evenly distributed over Eastern Mediterranean re...

Heat waves are considered to be increasing in frequency and intensity whereas they comprise a significant weather-related cause of deaths in several countries. Two heat waves occurred in Greece in summer 2007. These severe heat waves are assessed by analyzing the prevailing synoptic conditions, evaluating human thermal discomfort, through the Heat...

Elevated solar ultraviolet radiation associated with stratospheric ozone reduction may exert significant increases in the UV radiant flux reaching the ground surface mainly in the UVB (280–315 nm) spectral portion. This study aiming to explore the UV radiant flux levels in the eastern Mediterranean belt, hourly measurements of global UVB (Guvb), UV...

This paper evaluates the role of meteorological factors on the configuration of the complex aerosol's character at a suburban area of Athens, Greece. To this effort, 4-month period measurements of hourly PM2.5 aerosol samples were employed, being collected with the aid of a conventional R&P TEOM (model 1400a) at Aghia Paraskevi. The simultaneous da...

In this paper an effort is made to assess the link between urban changes and major sport events with the use of Earth Observation (EO). Particular emphasis is given to a) the simulation of the contribution of urban greening to the microclimate of an area which during the Olympic Games of Athens 2004 hosted a number of sporting facilities and b) to...

The main findings obtained from the research that was carried out in the framework of the European research project INTAS-94-1453 are presented. The objectives of this study were the following: (a) the derivation of a cyclic model of long-term and superlong-term forecasting of total ozone content (TOC), (b) the numerical modelling of ozone variabil...

This study explores the influence of air gaseous pollutants–aerosols and solar zenith angle (SZA) on the spectral diffuse-to-direct beam E dλ/E bλ irradiances ratio. It does so using ground-based spectroradiometric measurements taken over the Athens atmosphere during May 1995. It was found that the spectral E dλ/E bλ ratio decreases rapidly with in...

The depletion in the concentration of ozone layer in the stratosphere may significantly increase the UV radiant flux levels (mainly the UVB, 280–315 nm) reaching the earth's surface. These modifications have raised concern among scientists and policy makers during the last two decades so that numerous field experiments have been conducted illustrat...

Precipitation regime over Greece is controlled by the atmospheric circulation, orography sea surface temperature distribution and land/sea interaction. Previous studies have shown that the precipitation amounts are increased in Western Greece, which is located in the upstream side of the largest mountain range of the central mainland. Furthermore,...

During the peak of an extensive heat wave episode on 23-25 July 2007, simultaneous thermophysiological measurements were made in two non-acclimated healthy adults of different sex in a suburban area of Greater Athens, Greece. Based on experimental measurements of mean skin temperature and metabolic heat production, heat fluxes to and from the human...

Previous research has shown that temperature and humidity affect human health. However, only a few studies have examined the association of a biometeorological index, which combines several meteorological parameters and human physiology, with health outcomes. The aim of the present study is to assess the thermal discomfort in Athens city by using t...

The aim of this study is to estimate future potential changes in duration of extreme dry and wet spells and rainfall intensity in Eastern Mediterranean. For this purpose, daily precipitation amounts, deriving from the regional climate model of UK Hadley Centre HadRM3P have been used for the present (1960-1990) and the future period 2070-2100 on 0.4...

Airborne particulate matter (PM10, PM2.5, PM1) and volatile organic compounds (benzene, toluene, m,p-xylene, o-xylene) samples were collected during winter and summer seasons of 2005 at two sites, representing an urban and a suburban region of the Greater Athens Area. Urban site traffic emissions were the major contributor to the concentration of P...

Acoustic sounder derived profiles of the atmospheric velocity and temperature structure parameters, C v ² and C T ² , are presented. the former is obtained using a novel bistatic acoustic sounder comprising a fan beam transmitter and a vertically directed receiver. Simultaneous profiles of the temperature structure parameter are obtained using a co...

In this study, an attempt is made to investigate possible teleconnection patterns of atmospheric circulation, centered over eastern Mediterranean (EM) with the aid of gridded NCEP/NCAR daily values of geopotential heights for the period 1958–2003. For this purpose, two approaches have been used: correlation analysis and rotated principal component...

Unlabelled: Some indoor activities increase the number concentration of small particles and, hence, enhance the dose delivered to the lungs. The received particle dose indoors may exceed noticeably the dose from ambient air under routine in-house activities like cooking. In the present work, the internal dose by inhalation of ultrafine and fine pa...

We report the first observations of solar global UV (280–380 nm) radiation on the island of Cyprus obtained during an ongoing joint research project between the University of Athens and the Meteorological Service of Cyprus. Hourly global UV (Guv) and global (Gh) solar irradiances are measured and the relationship between the two radiant fluxes is i...

A teleconnection pattern has been identified between Eastern Mediterranean and North-western Europe in the geopotential fields of the upper troposphere (hereafter will be referred to as EMP) during winter and it seems to play significant role in the large-scale atmospheric circulation over Mediterranean region with distinctive temporal and spatial...

Using ground-based spectral solar extinction data taken in the Athens atmosphere during a field survey, experimental and modeled aerosol optical depths AOD have been retrieved. The Angstrom parameters α and β were derived through spectral extinction curves determined from a log–log plot fit in four spectral intervals, e.g. UV, VIS, UV-VIS and VIS-N...

The study of rainfall seasonality in different geographical areas in Greece using an individual seasonality index was the purpose of the present work. The correlation of the seasonality index ((SI) over bar, sum of the absolute deviation of mean monthly rainfall from the overall monthly mean divided by the mean annual rainfall) with the mean indivi...

The present work examines the temporal evolution of industrial contamination in sediments caused by trace metals in the Elefsis Gulf, Greece. The current state of contamination as well as the related sources can be obtained from the study of the sediments. Trace metals, namely Ni, Cu, Fe, and Mn, were collected during 1984-2003 by the local monitor...

It is the purpose of this paper to evaluate the different Sodar approaches and methods for the determination of the atmospheric mixing height against direct measurements. To achieve this objective a specific experiment was designed and performed incorporating, a research home made Sodar, a tethered balloon and a radiosonde facility as well as a con...

Results obtained using SPCTRAL2 parametric model for the polluted urban atmosphere of Athens, Greece, were analysed and compared with ground level experimental spectral solar irradiance measurements and spectrally integrated solar irradiances in two discrete narrow bands, ultraviolet and visible. For the aerosol characterization, the aerosol optica...

Coupling a building to the ground as a heat sink through earth-to-air heat exchangers can reduce the cooling energy demand during summer. The fans for circulating the air through the heat exchangers are usually grid connected. However, given that the cooling loads are almost in phase with the available solar irradiance, an innovative system couplin...

The relationship between the two radiant fluxes is studied from almost a 3-year data archive of hourly photosynthetically active photon flux (QP) and global solar irradiance (RS) performed at Athalassa, Cyprus. These data are used to determine temporal variability of the ratio (QP/RS) and its dependence on sky conditions. The seasonal variation of...

The primary objective of this work was the development of an operational system for early detection of oil-spills, monitoring of their evolution, and provision of support to responsible Public Authorities during cleanup operations, based on Remote Sensing and GIS technologies. In case of emergency, the principal characteristics of the oil spill are...

¶The relationship between global photosynthetically active radiation (PAR) and global solar radiation is studied with a 2-year data archive of hourly values HPAR and HSW of these irradiances obtained at Athalassa, Cyprus. These data are used to determine the temporal variability of HPAR and its dependence on sky conditions. The seasonal variation o...

Integrated environmental management in urban areas is nowadaysconsidered a sine qua non objective of Community and nationalenvironmental and development policies. A large amount ofscientific information on the state of the environment is nowavailable from a large pool of data sources. This work presentsan innovative method for integration of these...

An experimental campaign was carried out on a small Greek island that is characterized by complex terrain: its aim was to study the local characteristics of the vertical structure of the atmospheric boundary layer (ABL). The instrumentation was installed close to the shoreline and consisted of a 13-m-high meteorological mast instrumented at three l...

The present work extends an earlier investigation on buoyancy-driven air flow through a stairwell. A series of experiments was performed in order to study the coupled flows of mass and heat between the three floors of a full-scale residential building. A single tracer gas decay technique was adopted. Air flow rates through the specific stairwell we...

The development and characteristics of low level jets (LLJs) over the western site of a knife edge mountain in the Greater Athens area, Greece, is presented. The data were collected for a five-month period, with a commercial sodar-RASS profiling system that was placed at the foot of Mount Hymettus (1026 m) which is located on the north-south axis o...

Climatic measurements from almost 30 urban and suburban stations as well as specific measurements performed in 10 urban canyons in Athens, Greece, have been used to assess the impact of the urban climate on the energy consumption of buildings. It is found that for the city of Athens, where the mean heat island intensity exceeds 10°C, the cooling lo...

The dispersion of fire related air emissions depends greatly on the meteorological parameters and systems which influence the weather conditions at the site of interest. In this study, an interpretation of the physical meaning of the meteorological parameters at the surface, in the upper air and in relation to synoptic conditions is provided in an...

The use of an array of loudspeaker elements for an acoustic sounder antenna is discussed. The effect of variations between the phase and amplitude of individual elements in the array is investigated and measurements are compared with the predicted radiation patterns for both a 6*6 square array and a 2*12 rectangular array of re-entrant horn loudspe...

Details are given of an atmospheric acoustic sounder which can be used in both a rural area and a noisy town environment. The instrument has been used for the measurement of various parameters of the turbulent boundary layer including the temperature and velocity structure parameters CT2 and Cv2 as well as vertical wind speeds. A summary of some of...

The present work concerns the measurement and the computational fluid dynamics (CFD) modeling of buoyancy-driven air flow through a stairwell that connects the two individual floors of a residential building. A series of experiments was performed in order to study the mass and heat transfer between the two floors. Air flow rates through this stairw...