24 research outputs found
Heat risk map of Riyadh
No full text<p>The dataset is used to assess the urban heat risk in the city of Riyadh using proxy variables to evaluate the environmental, infrastructural, and social dimensions of the city.</p><p>The environmental component was evaluated using the mean values of land surface temperature (LST), air temperature (T2m), and discomfort index (DI) across the districts of Riyadh. These factors, derived from data like MODIS LST and available WRF simulations, represented the degree of heat exposure in different regions. </p><p>The infrastructural component of heat risk was evaluated by looking at the city's infrastructure, that is the building density per district. Buildings can act as "heat traps," thus higher building density suggests increased heat risk.</p><p>The social component considered demographic factors such as the percentage of the population over 65 old (OP) and under 14 years old (YP), which can indicate sensitivity to extreme heat conditions. </p><p>To map the heat risk, these components were combined into a composite heat risk indicator. For this to be achieved, each parameter was reclassified into three categories (1-less, 2-moderate, and 3-high) using the quantile classification which is a data classification method that distributes a set of values into groups that contain an equal number of values. </p><p> </p><p> LST (°C) DI T2m (°C) <14 y.o. (%) >65 y.o (%) Buildings per sq. m.(BD)</p><p>1-Less risk <47.2 <28 <40.6 <23 <1 <66</p><p>2-Moderate risk 47.2 ≤ LST ≤ 47.9 28≤ DI ≤ 28.2 40.6 ≤ T2m ≤ 40.8 23≤ YP ≤28 1≤ OP ≤ 3 66≤ BD ≤ 109</p><p>3-High risk >47.9 >28.2 >40.8 >28 >3 >109</p><p>LST: Land Surface Temperature; DI: Discomfort Index; T2m: Air temperature at 2m height; YP<14 y.o.: People under 14 years old; OP y.o.: Older people over 65 years old; </p><p>Since the relative importance of each parameter is unknown, we considered that all parameters contributed equally to the composite heat risk index and the arithmetic values were aggregated. The final value for each district was then reclassified into three categories using the quantile classification method resulting in the final three categories of Urban Heat Risk (Less heat risk, Moderate heat risk, High heat risk)</p>
Ομιλία περί του αγίου πρίγκιπος Λαζάρου του Αντωνίου Ραφαήλ Επακτίτου: Αφηγηματικά μοτίβα και ηγεμονική ιδεολογία.
No full textHomily about Saint Prince Lazar by Antonie Raphael Epaktites: Narrative Motifs and Hegemonic Ideology. In a period of three decades after the battle of Kosovo and the defeat of the Serbs in 1389, ten writers described the fatal and catalytic for the historical development of Serbia and the wider region martyrdom of Prince Lazar Hrebelianović. Antonie Raphael Epaktites, that is, the foreigner, was the tenth well-known author, who essentially closes the thematic cycle of the battle of Kosovo with the Homily about St. Lazar, a text, as Podskalsky claims, which is between a historical narrative and a poetic praise. In this presentation we explore what are the structural narrative motifs with which the author sketches the portrait of Prince Lazar, the overall iconography, the symbolism and how they relate to the hegemonic ideology. Λέξεις κλειδια: Ομιλία, Άγιος Πρίγκιπας Λάζαρος, Αντώνιος Ραφαήλ Επακτίτης, Αφηγηματικά Μοτίβα, Ηγεμονική Ιδεολογία.Key words: Homily, Saint Prince Lazar, Antonie Raphael Epaktites, Narrative Motifs, Hegemonic Ideology
Quantifying the Trends in Land Surface Temperature and Surface Urban Heat Island Intensity in Mediterranean Cities in View of Smart Urbanization
No full textLand Surface Temperature (LST) is a key parameter for the estimation of urban fluxes as well as for the assessment of the presence and strength of the surface urban heat island (SUHI). In an urban environment, LST depends on the way the city has been planned and developed over time. To this end, the estimation of LST needs adequate spatial and temporal data at the urban scale, especially with respect to land cover/land use. The present study is divided in two parts: at first, satellite data from MODIS-Terra 8-day product (MOD11A2) were used for the analysis of an eighteen-year time series (2001–2017) of the LST spatial and temporal distribution in five major cities of the Mediterranean during the summer months. LST trends were retrieved and assessed for their statistical significance. Secondly, LST values and trends for each city were examined in relation to land cover characteristics and patterns in order to define the contribution of urban development and planning on LST; this information is important for the drafting of smart urbanization policies and measures. Results revealed (a) positive LST trends in the urban areas especially during nighttime ranging from +0.412 °K in Marseille to +0.923 °K in Cairo and (b) the SUHI has intensified during the last eighteen years especially during daytime in European Mediterranean cities, such as Rome (+0.332 °K) and Barcelona (+0.307 °K)
Global Climatology of the Daytime Surface Cooling of Urban Parks Using Satellite Observations
No full textGreen infrastructure-based heat mitigation strategies can help alleviate the overheating burden on urban residents. While the cooling effect of parks has been explored in individual satellite-based studies, a global, multi-year investigation has been lacking. This study provides a comprehensive global assessment of the daytime surface park cool island (SPCI) climatology, using land surface temperatures from 2,083 systematically selected parks worldwide (2013–2022). Through detailed park selection and data stratification, the key drivers influencing the observed SPCI intensity are isolated. The analysis reveals that cooling is strongly linked to park type, with well-treed parks being, on average, 3.4°C, cooler than the surrounding urban area during summer. It is further investigated how SPCI is influenced by seasonal variations, droughts, and urban morphology across diverse background climates. These findings, along with the developed global SPCI data set, offer critical insights for designing climate-resilient green spaces. © 2025. The Author(s)
Recognition of Thermal Hot and Cold Spots in Urban Areas in Support of Mitigation Plans to Counteract Overheating: Application for Athens
No full textMitigation plans to counteract overheating in urban areas need to be based on a thorough knowledge of the state of the thermal environment, most importantly on the presence of areas which consistently demonstrate higher or lower urban land surface temperatures (hereinafter referred to as “hot spots” or “cold spots”, respectively). The main objective of this research study is to develop a methodological approach for the recognition of thermal “hot spots” and “cold spots” in urban areas during summer; this is accomplished with (a) the combined use of high and medium spatial resolution satellite data (Landsat 8 and Terra-MODIS, respectively); (b) the downscaling of the Terra-MODIS satellite data so as to acquire spatial resolution similar to the Landsat one and at the same time take advantage of the high revisit time as compared to the respective one of Landsat (16 days); and (c) the application of a statistical clustering technique to recognize “hot spots” and “cold spots”. The methodological approach was applied as a case study for the urban area of Athens, Greece for a summer period. Results demonstrated the capacity of the methodological approach to recognize “hot spots” and “cold spots”, revealed a strong relationship between land use and “hot spots” and “cold spots”, and showed that the average land surface temperature (LST) difference between the “hot spots” and “cold spots” can reach 9.1 °K
Can Satellite-Based Thermal Anomalies Be Indicative of Heatwaves? An Investigation for MODIS Land Surface Temperatures in the Mediterranean Region
No full textIn recent years, an exceptional number of record-shattering temperature extremes have been observed, resulting in significant societal and environmental impacts. The Mediterranean region is particularly thermally vulnerable, frequently suffering from intense and severe heatwaves. Using daily temperature observations from 58 weather stations (NOAA Global Historical Climatology Network daily database) in the Mediterranean area, past heatwave episodes were initially detected. A daily LST time series was developed using Land Surface Temperature (LST) products from Moderate Resolution Imaging Spectroradiometer (MODIS) (Terra & Aqua satellites) for a 19-year period (2002–2020) at the station locations. LST anomalies were identified using percentile-based indices. It was found that remotely sensed-based LST presents the potential for understanding and monitoring heatwave events, as surface thermal anomalies were generally indicative of heatwaves. Approximately 42% (39%) of heatwave days during daytime (nighttime) coincided with LST anomalies; conversely, 51% of daytime LST anomalies overlapped with the exact days of a heatwave (38% at night). Importantly, the degree of association was significantly higher for extremely hot days (up to an 80% match) and long-lasting heatwaves (up to an 85% match). Rising trends in frequency and duration were observed for both heatwaves and LST anomalies. The results advance the understanding of surface-atmosphere coupling during extreme temperature days and reflect the suitability of thermal remote sensing in heatwave preparedness strategies
Supplementary dataset for "Daytime surface park cool island magnitude across global cities"
No full text<p>This dataset is supplementary to the paper "<strong>Daytime surface park cool island magnitude across global cities</strong>" by Agathangeldis et al. The vector file "parks.gpkg" contains the boundaries of the parks that were used in the study, with additional metadata as attributes.</p>
A Methodology for Bridging the Gap between Regional- and City-Scale Climate Simulations for the Urban Thermal Environment
No full textThe main objective of this study is to bridge the gap between regional- and city-scale climate simulations, with the focus given to the thermal environment. A dynamic-statistical downscaling methodology for defining daily maximum (Tmax) and minimum (Tmin) temperatures is developed based on artificial neural networks (ANNs) and multiple linear regression models (MLRs). The approach involves the use of simulations from two EURO-CORDEX regional climate models (RCMs) (at approximately 12 km × 12 km) that are further downscaled to a finer resolution (1 km × 1 km). A feature selection methodology is applied to select the optimum subset of parameters for training the machine learning models. The downscaling methodology is initially applied to two RCMs, driven by the ERA-Interim reanalysis (2008–2011) and high-resolution urban climate model simulations (UrbClims). The performance of the relationships is validated and found to successfully simulate the spatiotemporal distribution of Tmax and Tmin over Athens. Finally, the relationships that were extracted by the models are further used to quantify changes for Tmax and Tmin in high resolution, between the historical period (1971–2000) and mid-century (2041–2071) climate projections for two different representative concentration pathways (RCP4.5 and RCP8.5). Based on the results, both mean Tmax and Tmin are estimated to increase by 1.7 °C and 1.5 °C for RCP4.5 and 2.3 °C and 2.1 °C for RCP8.5, respectively, with distinct spatiotemporal patterns over the study area
Global Climatology of the Daytime Surface Cooling of Urban Parks Using Satellite Observations
Get PDFAbstract Green infrastructure‐based heat mitigation strategies can help alleviate the overheating burden on urban residents. While the cooling effect of parks has been explored in individual satellite‐based studies, a global, multi‐year investigation has been lacking. This study provides a comprehensive global assessment of the daytime surface park cool island (SPCI) climatology, using land surface temperatures from 2,083 systematically selected parks worldwide (2013–2022). Through detailed park selection and data stratification, the key drivers influencing the observed SPCI intensity are isolated. The analysis reveals that cooling is strongly linked to park type, with well‐treed parks being, on average, 3.4°C, cooler than the surrounding urban area during summer. It is further investigated how SPCI is influenced by seasonal variations, droughts, and urban morphology across diverse background climates. These findings, along with the developed global SPCI data set, offer critical insights for designing climate‐resilient green spaces
Achieving digital education in primary schools: Success factors and policy recommendations
No full textThis paper examines the current education policy for achieving digital education in European Union overall and in Greece specifically. By using a theoretical framework of policy enactment, this study explored different factors which could predict technology integration and digital education. A survey was conducted with 205 classroom teachers across 32 primary schools in Greece. The analysis tracked the progress towards achieving digital education. The results of this study confirmed that current policies are accurately targeted on significant areas which are predictors of technology integration. This paper recommends strategies for achieving, scaling, and sustaining school system improvement for digital education. © The Author(s) 2024
