Christos Giannaros

National and Kapodistrian University of Athens | uoa · Department of Environmental Physics and Meteorology

This study presents a comprehensive modeling approach for simulating the spatiotemporal distribution of urban air temperatures with a modeling system that includes the Weather Research and Forecasting (WRF) model and the Single-Layer Urban Canopy Model (SLUCM) with a modified treatment of the impervious surface temperature. The model was applied to...

The derivation of global navigation satellite systems (GNSSs) tropospheric products is nowadays a state-of-the-art technique that serves both research and operational needs in a broad range of applications in meteorology. In particular, GNSS zenith tropospheric delay (ZTD) data assimilation is widely applied in Europe to enhance numerical weather p...

The CyFFORS (Cyprus Flood Forecasting System) project aims at increasing flood risk awareness and promoting preparedness against flooding by developing and validating a pilot flood forecasting system targeted over three river/stream basins in the Larnaca region, Cyprus, and Attica region, Greece. The present study demonstrates the analysis of flood...

Previous studies assessing population exposure to heat stress have focused primarily on environmental heat loads without accounting for variations in human thermo–physiological responses to heat. A novel 30-year (1991–2020) human thermal bioclimate dataset, consisting of hourly mPET (modified physiologically equivalent temperature) values for diver...

Europe and the Mediterranean are considered climate change hot spots. This is the reason why this paper focuses on the analysis of the trends of essential climate variables in a Mediterranean country, Greece. The analyzed period is 1991–2020, and the dataset used is ERA5-Land (produced by the European Center for Medium-Range Weather Forecasts), whi...

Existing assessments of the thermal-related impact of the environment on humans are often limited by the use of data that are not representative of the population exposure and/or not consider a human centred approach. Here, we combine high resolution regional retrospective analysis (reanalysis), population data and human energy balance modelling, i...

Greece is characterized by a significant warming trend in recent decades, accompanied by increasing frequency, intensity, and duration of heat waves (HWs). A particularly devastating HW that affected the country was the late July/early August 2021 event (JA2021HW), which lasted for 9 days (July 28–August 5). Focusing on the hottest day of the event...

Europe has been experiencing an increasing number of sweltering heat waves in recent years. This run of hot extremes induces a significant impact on the human environment, especially in terms of excess mortality, highlighting the urgent need for improved heat-health action planning. This is particularly true in countries situated in the eastern Med...

In recent years, a considerable body of research has demonstrated the suitability of global and regional reanalysis data for human-biometeorological applications. These applications include the assessment of the outdoor thermal environment and the investigation of its relation to human health, especially in areas where the spatial coverage of surfa...

This study examines the effects of short-term exposure to PM10 and O3 on all-cause, cardiorespiratory, and cerebrovascular mortality in the urban area of Thessaloniki, Greece. An analysis was performed on the vulnerable subgroup (the elderly population). The primary effect estimates employed were the relative risks for every 10 µg/m3 increase in ai...

Heatwave events are of major concern in the global context, since they can significantly impact ecosystems, economies and societies. For this reason, more detailed analyses of the characteristics and trends of heatwaves represent a priority that cannot be neglected. In this study, the interannual and decadal variability of seven indices of heatwave...

Greece was affected by a prolonged and extreme heat wave (HW) event (July 28–August 05) during the abnormally hot summer of 2021, with the maximum temperature in Athens, the capital of the country, reaching up to 43.9 °C in the city center. This observation corresponds to the second highest maximum temperature recorded since 1900, based on the hist...

The current study presents the first attempt to investigate the November 2019 catastrophic flash flood in Olympiada (North Greece) under an operational forecasting and monitoring context, based on the mesoscale weather and research forecasting (WRF) model and the integrated multi-satellite retrievals for global precipitation measurement (GPM-IMERG)...

Extreme temperatures, either elevated or low, are known to cause adverse impacts on the natural and human environment. Increased hospital admissions and mortality rates during heat and cold waves demonstrate the severity of the problem concerning human health. Heat waves (HWs) are expected to become more severe in terms of frequency, intensity, and...

Although there is a growing interest in the association between ambient temperatures and mortality, little evidence is available for Thessaloniki, the second largest city of Greece. In this study, we present an assessment of the effects of temperature on daily mortality from 2006 to 2016 in the urban area of Thessaloniki, by describing the exposure...

This paper is devoted to the discussion of the practice of storm naming that has been initiated in January 2017 for the first time in the Eastern Mediterranean Region. Namely the METEO Unit at NOA, taking into consideration that storm naming facilitates meteorologists, researchers, authorities, civil protection officers, the media and citizens to c...

An integrated modeling approach for forecasting flood events is presented in the current study. An advanced flood forecasting model, which is based on the coupling of hydrological and atmospheric components, was used for a twofold objective: first to investigate the potential of a coupled hydrometeorological model to be used for flood forecasting a...

The Southeast Mediterranean (SEM) is characterized by increased vulnerability to river/stream flooding. However, impact-oriented, operational fluvial flood forecasting is far away from maturity in the region. The current paper presents the first attempt at introducing an operational impact-based warning system in the area, which is founded on the c...

Post-processing techniques can provide significant improvement in the forecast skill of air quality models. In this study, the implementation of an analog-based technique to Comprehensive Air Quality Model with Extensions (CAMx) coupled with Weather Research and Forecasting (WRF) model results is examined. WRF-CAMx runs with a 2-km horizontal grid...

During February 2019, two severe storms affected the island of Crete, located in south Greece. Both storms produced excessive rainfall, provoking severe damages, especially in the western part of Crete. The role of the prevailing synoptic patterns and the interaction of the flow with the high mountains of Crete were investigated. For this purpose,...

Στις 25 Νοεμβρίου του 2019, ισχυρή βροχόπτωση με υψηλή ραγδαιότητα έπληξε την Ανατολική Χαλκιδική που είχε ως αποτέλεσμα καταστροφικά πλημμυρικά φαινόμενα. Στην παρούσα εργασία αναλύεται η απόκριση της λεκάνης απορροής του χειμάρρου «Μπασδέκη», κοντά στον οικισμό της Ολυμπιάδας, κατά την διάρκεια του φαινομένου. Για τον σκοπό αυτό εκτιμήθηκε η απορ...

Abstract. An integrated modeling approach for simulating flood events is presented in the current study. An advanced flood forecasting model, which is based on the coupling of hydrological and atmospheric components, was used for a twofold objective: first to investigate the potential of a coupled hydrometeorological model to be used for flood fore...

In the framework of the European Union co-funded project “BalkanMed real time severe weather service (BeRTISS)”, the feasibility of improved precipitation nowcasts and forecasts is assessed, using Global Navigation Satellite Systems (GNSS) data. For this work, one year (2018) data of Integrated Water Vapor (IWV) and Zenith Total Delay (ZTD) hourly...

In the framework of the European Union co-funded project "BalkanMed real time severe weather service (BeRTISS)", the feasibility of improved precipitation nowcasting and forecastig is assessed, using Global Navigation Satellite Systems (GNSS) data. For this work, one year (2018) data of Integrated Water Vapor (IWP) and Zenith Total Delay (ZTD) hour...

In order to study the years of the outbreak of the financial crisis in Greece, we use a continuous eight-year record (2008–2015) of formaldehyde, HCHO, columns retrieved from the GOME-2/MetOp-A and GOME-2/MetOp-B satellite instruments over two urban Greek regions, Thessaloniki and Athens. A statistical linear regression analysis that was applied to...

The current study investigated the impact of the Weather Research and Forecasting (WRF) (a) surface layer (SL), (b) land surface and (c) planetary boundary layer (PBL) physics on the short-term simulation of the meteorological and human thermal comfort conditions during 15 heat waves identified between 2004 and 2013 in the southeast Mediterranean a...

Mineral dust is one of the major contributors of particulate matter in Middle East. Dust events originated from local sources can lead to PM10 concentrations of more than 1000 μg/m3, with consequent adverse impact on human health. Such events are often associated with a special wind pattern, called Shamal. In this study a Shamal event is investigat...

Middle East Area and especially the central part is a dust dominated domain and therefore estimation of natural dust emissions is critical. Aim of this study is to assess the sensitivity of state-of-the art dust modules, utilized in multiple modelling schemes, and especially of their three main components; namely the horizontal mass flux, the drag...

One of the main issues arising from the comparison of ground-based and satellite measurements is the difference in spatial representativeness, which for locations with inhomogeneous spatial distribution of pollutants may lead to significant differences between the two data sets. In order to investigate the spatial variability of tropospheric NO2 wi...

Heat-waves are strongly connected with environmental, health and socioeconomic impacts. The frequency of occurrence and the intensity of those events tend to increase across the Mediterranean due to climate change. Numerical weather prediction models are considered to be an important tool for predicting heat-wave events. Additionally, they are suit...

The impact of cruise and passenger ship emissions on air quality and human health risk in the greater Thessaloniki area has been studied for the present and future time. The study focuses on the pollutants regulated by the EU legislation. Simulations have been performed using the CALPUFF dispersion model for 2013, in order to estimate the pollutant...

Phaethon is a ground-based MAX-DOAS system, easily deployed at different locations to address specific air quality problems and support satellite validation studies. Three Phaethon systems have been deployed at different sites in the greater area of Thessaloniki, characterized by diverse local pollution levels representing urban, suburban and rural...

A modeling system that consists of the meteorological model WRF and the photochemical model CAMx has been applied in very high horizontal resolution (2 km) in order to assess the air quality in Greece. An updated, high resolution emission inventory was compiled for all the main anthropogenic pollutants (CO, NOx, SO2, NMVOCs, PM10, PM2.5) while emis...

Formaldehyde (CH2O) is an important indicator of tropospheric hydrocarbon emissions and photochemical activity. CH2O is a high-yield intermediate product from the oxidation of Non-Methane Volatile Organic Compounds (NMVOCs) emitted by anthropogenic, biogenic, and biomass burning activities. For the past 30 years CH2O can be measured from space in t...

The main issue arising from the comparison of ground-based and satellite measurements is the difference in spatial representativeness, which for locations with inhomogeneous spatial distribution of pollutants may lead to significant differences between the two datasets. In order to investigate the spatial variability of tropospheric NO2 within a su...

Urban Greek regions (Thessaloniki and Athens) displaying increased HCHO vertical column densities, that are probably linked to anthropogenic emissions (biomass burning and urban pollution), have been identified using satellite observations during wintertime. The intensive and increased use of woods and pellets for domestic heating due to the inhabi...

This paper describes the pre-operational analysis and forecasting system developed during MACC (Monitoring Atmospheric Composition and Climate) and continued in the MACC-II (Monitoring Atmospheric Composition and Climate: Interim Implementation) European projects to provide air quality services for the European continent. This system is based on se...

The increase of the ship traffic for touristic and commercial purposes is one of the EU Blue Growth targets. The Adriatic/Ionian is one of the sea-basin strategic areas for this target. The purpose of the study is the examination of the impact of the ship emissions on the gaseous and particulate pollutants concentrations in the Adriatic/Ionian area...

An increase of the passenger ships traffic is expected in the Mediterranean Sea as targeted by the EU Blue Growth initiative. This increase is expected to impact the Mediterranean port-cities air quality considering not only the conventional atmospheric pollutants but also the toxic ones that are emitted by the ships (e.g. Nickel). The aim of this...

This paper describes the pre-operational analysis and forecasting system developed during MACC (Monitoring Atmospheric Composition and Climate) and continued in MACC-II (Monitoring Atmospheric Composition and Climate: Interim Implementation) European projects to provide air quality services for the European continent. The paper gives an overall pic...

The paper presents a comprehensive analysis of the most basic features of the air quality of a Mediterranean urban environment area. The impact of meteorology on the air quality is also examined. Observational surface concentrations of the most important air pollutants, recorded at two measuring stations in Patras, Greece, are used. The Weather Res...

Aim of this Master Thesis is the evaluation of the mesoscale meteorological model WRF v. 3.2, which is used operationally by the Laboratory of Atmospheric Physics (LAP), Department of Physics, Aristotle University of Thessaloniki (AUTH). For this purpose, the method of comparing the model results with observations for the same region of interest, G...

Wind energy is a form of mild and renewable energy which equals a small percentage of solar energy (~20%) and is manifested in the form of kinetic energy of air. The development of technology for the exploitation of wind energy, coupled to the environmental condition of the planet and the continuing rise in the energy and financial costs for the ex...