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27 results on '"Tsiros, Ioannis"'

1. Reflectance and Thermal Micrometeorological Characteristics of an Urban Green Space in the Mediterranean During July's 2023 Heatwave.

Author

Proutsos, Nikolaos D., Solomou, Alexandra D., Stefanidis, Stefanos P., and Tsiros, Ioannis X.

Abstract

The thermal and optical behavior of different elements in the urban environment is critical for urban climate regulation and planning. This study investigates the micrometeorological conditions prevailing in an urban green space (UGS) in Greece, during the heatwave of July 2023, addressing the effects of various surface materials on thermal dynamics and the urban heat island (UHI) phenomenon. The research is based on ground surface temperature and albedo measurements on different materials in the UGS, in the morning and at noon, showing great temperature differences between the different types of materials. The findings highlight the complex interaction between high-albedo surfaces and surface temperature values, suggesting that the proper selection of materials can highly affect the optical and thermal behavior of the urban environment. Artificial materials absorb more heat compared to natural vegetation, leading to high surface temperature values, reaching at noon, for example, 58.9 °C for asphalt. For the natural surfaces, dry bare soil presents similar thermal behavior (64.1 °C at noon), while green surfaces had much lower temperatures (e.g., 38.3 °C for grass). Thermal comfort indices revealed that July 2023 experienced extensive "very hot" conditions, imposing the urgent need for strategic urban planning to mitigate heat impacts. The study highlights that in order to create climate-resilient environments and improve thermal comfort, it is crucial to include suitable materials and a variety of vegetation in urban design. Such insights into the complex nature of urban microclimate indicates also the issue of the careful selection of materials and plant species in urban greening initiatives to help cities face the UHI phenomenon. [ABSTRACT FROM AUTHOR]

Published
2025
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5. Evaluating the effects of green roofs and green façade as an urban heat island adaptation strategy

Author

Tseliou Areti, Melas Emmanouil, Mela Athina, and Tsiros Ioannis

Subjects
Environmental sciences, GE1-350
Abstract

The present study investigated the potential cooling effect of green roofs and green façades on a residential neighborhood in Athens during a typical summer day. The numerical model ENVI-met was employed to simulate the thermal environment of the study area at the existing configuration. Then, different design interventions focusing on the application of green façade and green roofs on the rooftops of the existing buildings were developed in order to evaluate the potential amelioration of the adverse thermal conditions. Thermal conditions were assessed based on basic meteorological parameter values and well-known thermal indices estimations. Results showed that at a two-floor building rooftop, the thermal conditions improved only slightly. Most importantly, the inclusive green roofs did not configure a significant cooling effect compared to that of low-height vegetation existing in the exclusive green roofs. Finally, results showed that the synergetic effect of green roofs and green façade produced a greater amelioration of thermal comfort conditions, compared to that produced by the green roofs solely. The greatest amelioration of thermal sensation conditions was achieved by the combination of inclusive green roofs and green façade.

Published
2023
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14. Evaluation of Urban Bioclimatic Measurements towards an Easier and more Affordable Method of Instrumental Monitoring.

Author

Melas, Emmanouil, Mela, Athina, Tsiros, Ioannis, and Varelidis, Georgios

Subjects
BIOCLIMATOLOGY, URBAN climatology, PUBLIC spaces, ATMOSPHERIC temperature, HUMIDITY
Abstract

Thermal comfort is a key aspect of optimal conditions in urban public spaces. Air temperature, relative humidity, wind speed, and globe temperature measurements are critical components of bioclimatic research in the broader scientific field of urban space quality assessment. The evaluation of thermal comfort in public spaces frequently requires field measurements over long periods and at multiple sites at the same time. This can be challenging on a qualitative and quantitative level. Finding the most accurate way to collect such data in an accessible and manageable way is crucial in the context of an urban field study. Data from various instruments were evaluated and statistically compared in order to assess possible instrument synergy or even similarities that would allow a transition to a simplified way of measuring these determinants of thermal comfort. [ABSTRACT FROM AUTHOR]

Published
2023
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15. Artificial Neural Network Models for the Estimation of Air Temperature Cooling and Warming Patterns Inside Urban Clusters: The Case of Courtyards in Athens, Greece.

Author

Thoma, Eleni, Moustris, Konstantinos, Tseliou, Areti, Papadopoulos, George, and Tsiros, Ioannis

Subjects
ATMOSPHERIC temperature, ARTIFICIAL neural networks, URBAN planning, HUMIDITY
Abstract

In the present study, the microclimatic conditions of two courtyards in the city of Athens are evaluated based on filed monitoring data and data predicted by artificial neural network models (ANNs). The study focuses on the development and application of ANNs in order to estimate air temperature and relative humidity values in complex urban forms such as courtyards from a standard meteorological station, using air temperature and relative humidity as the only inputs. The results are then evaluated to identify the prognostic ability of the developed ANNs models, showing a remarkable predictive ability. [ABSTRACT FROM AUTHOR]

Published
2023
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16. Environmental Impact of Urban Design Elements in a Mediterranean City.

Author

Tseliou, Areti, Melas, Emmanouil, Mela, Athina, and Tsiros, Ioannis

Subjects
URBAN planning, ENVIRONMENTAL impact analysis, CONSTRUCTION materials, ATMOSPHERIC temperature, CLIMATE change
Abstract

Today, high-density building areas, along with low albedo construction materials and a lack of green spaces, have led to higher urban temperatures. Climate change significantly intensifies the magnitude of urban overheating and the frequency of extreme heat events is expected to increase over time. The aim of this research is to showcase new insights into the cooling effects of urban elements and layouts in a residential area consisting of several building blocks in a Mediterranean city (Athens). The microclimatic model ENVI-met was applied to simulate thermal conditions for a typical summer day. Thermal conditions were evaluated according to air temperature and the estimations of the Universal Climate Thermal Index (UTCI, °C). The results showed that during the hottest hours of the day (11:00-17:00), among the examined design layouts, courtyards and the NS street induced the lower heat stress conditions, that fluctuated within the 'Moderate heat stress' condition. On the opposite end, the EW street, the avenue, the trees, and the pavement-affected areas induced 'Very strong heat stress' conditions. The maximum UTCI value, 40.9 °C (15:00 LST), was obtained in the areas affected by the EW street. The findings of this study highlighted the urban design layout patterns that enhance the development of hotspots and should be considered when designing mitigation strategies in cities with a Mediterranean climate. [ABSTRACT FROM AUTHOR]

Published
2023
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18. Air quality and meteorological patterns of an early spring heatwave event in an industrialized area of Attica, Greece

Author

Mavrakis, Anastasios Kapsali, Athanasia Tsiros, Ioannis X. and Pantavou, Katerina

Abstract

Heatwaves-excessively hot ambient conditions that are considered a serious threat to human health-are often associated with poor air quality. The aim of this study was to examine the impact of an early heatwave episode in an industrialized plain in the eastern Mediterranean region (Thriasio, Greece) on human thermal discomfort and urban air quality. The heatwave occurred in mid (15-20) May 2020, shortly after some of the restrictions that were improsed to halt the spread of coronavirus disease 2019 (COVID-19) in Greece were lifted (on 4 May). The discomfort index (DI) and the daily air quality index (DAQI) were calculated on an hourly basis throughout spring 2020 (March, April, May) using data from two stations that measure meteorological parameters and air pollutant concentrations in the Thriasio Plain. The analysis showed that the air temperature increased during 7-17 May to levels that were more than 10 degrees C above the monthly average value (25.8 degrees C). The maximum measured air temperature was 38 degrees C (on 17 May). The results showed a high level of thermal discomfort. The DI exceeded the threshold of 24 degrees C for several hours during 13-20 May. Increased air pollution levels were also identified. The average DAQI was estimated as 0.83 +/- 0.1 and 1.14 +/- 0.2 at two monitoring stations in the region of interest during the heatwave. Particulate matter (diameter < 10 mu m) appeared to contribute significantly to the poor air quality. Significant correlations between the air temperature, DI, and AQSI were also identified.

Published
2021

19. A note on some uncertainties associated with Thornthwaite's aridity index introduced by using different potential evapotranspiration methods

Author

Proutsos, Nikolaos D. Tsiros, Ioannis X. Nastos, Panagiotis and Tsaousidis, Alexandros

Abstract

Potential evapotranspiration (PET) is a key parameter for climate classification and aridity assessment. The widely used UNEP (1992) classification system is based on the estimation of the aridity index AI, which requires annual average values of precipitation P and PET. For the calculation of PET the Thornthwaite's (1948) formula is, in principle, suggested. Recent studies use more advanced and accurate methods for PET estimation but apply to AI the same thresholds proposed by UNEP for aridity classification. This work deals with the uncertainties introduced by the use of different PET methods in the estimation of the aridity index AI. Specifically, the Hargreaves-Samani (HS) method and four of its modifications, three modifications of Thornthwaite's formula and the equation of Hamon, are evaluated against the widely used Thornthwaite's original method, by assessing their impact on the AI. Climatic data as monthly average values of at least 30 years of measurements from 122 stations in the Greek peninsula are used. Results show that AI is highly affected by the PET method adopted, resulting thus to changes in climatic classification of a region. Further, results imply the need for an adjustment of the threshold values that determine aridity classes according to the method each time adopted. Therefore, new threshold values for the aridity classes are developed and presented in this work. The proposed threshold values cover a range of sites that belong to semi-arid SA, sub-humid SH and humid H aridity classes of the Greek peninsula.

Published
2021

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