This study analyzes inter- and intra-zonal seasonal variability of surface urban heat islands (SUHIs) within the methodological framework of local climate zones (LCZs) in three central European ...cities (Prague, Brno and Novi Sad). These cities differ in urban area and structure as well as in topography and hinterland land-cover features. LCZs were delineated on the basis of a GIS-based classification method. Land surface temperature (LST) was derived from LANDSAT-8 scenes in the period 2013–2018. The first step was to detect seasonal SUHI intensity differences for built LCZ types and LST for land-cover types of LCZ. The results revealed the highest differences in summer and spring, and lowest in winter. The highest SUHI intensity values occur in densely built-up and industrial zones, and the lowest in sparsely-built city outskirts. The coolest LCZs based on LST were dense trees and water areas in spring and summer. The second step aimed to analyze the effects of vegetation on SUHI formation. Hence, 11 land cover subclasses (from dense trees to bush/scrub) were defined in order to research intra-zonal seasonal LST variability. The height and density of vegetation have substantial effects on intra-zonal variability of LST in land-cover types of LCZ, whereas differences between forest subclasses were relatively low. Finally, the character of the vegetation had a substantial influence on intra-zonal LCZ variability of LST and SUHI formation. Further research in this field could contribute to better understanding of micro- and mezzo-climate-scale patterns, as well as better adaptation to climate change in urban areas.
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•Statistically significant seasonal SUHI variability between LCZs.•Highest SUHI differences between built and land cover classes occurred in summer.•Regional climate and city surrounding affect SUHI during winter, spring and autumn.•Statistically significant SUHI variability within LCZ land cover classes (A−C).•Density and tree/scrub pattern, together with land cover, affect seasonal SUHI.
This study uses the MUKLIMO_3 urban climate model (in German, Mikroskaliges Urbanes KLImaMOdell in 3-Dimensionen) and measurements from an urban climate network in order to simulate, validate and ...analyse the spatiotemporal pattern of human thermal comfort outdoors in the city of Brno (Czech Republic) during a heat-wave period. HUMIDEX, a heat index designed to quantify human heat exposure, was employed to assess thermal comfort, employing air temperature and relative humidity data. The city was divided into local climate zones (LCZs) in order to access differences in intra-urban thermal comfort. Validation of the model results, based on the measurement dates within the urban monitoring network, confirmed that the MUKLIMO_3 micro-scale model had the capacity to simulate the main spatiotemporal patterns of thermal comfort in an urban area and its vicinity. The results suggested that statistically significant differences in outdoor thermal comfort exist in the majority of cases between different LCZs. The most built-up LCZ types (LCZs 2, 3, 5, 8 and 10) were disclosed as the most uncomfortable areas of the city. Hence, conditions of great discomfort (HUMIDEX >40) were recorded in these areas, mainly in the afternoon hours (from 13.00 to 18.00 CEST), while some thermal discomfort continued overnight. In contrast, HUMIDEX values in sparsely built-up LCZ 9 and non-urban LCZs were substantially lower and indicated better thermal conditions for the urban population. Interestingly, the model captured a local increase of HUMIDEX values arising out of air humidity in LCZs with the presence of more vegetation (LCZs A and B) and in the vicinity of larger bodies of water (LCZ G).
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•MUKLIMO_3 model was suitable for spatiotemporal thermal comfort simulations.•Significant outdoor thermal comfort differences exist among the majority of LCZs.•The most uncomfortable areas of the city were LCZs 2, 3, 5, 8 and 10.•The most comfortable areas were land-cover types from A to G and LCZ 9.•Air humidity increased HUMIDEX values in “green” and “blue” research areas.
A comprehensive analysis of meteorological (air temperature, relative humidity, wind speed and global radiation) and outdoor thermal comfort (OTC) conditions (Physiological Equivalent Temperature and ...Mean Radiant Temperature) was carried out in six Local Climate Zones (LCZs) in Ghent (Belgium) on annual and seasonal level (2017) and during two heat waves (moderate in 2017 and record-breaking in 2019). The continuously monitored data originates from the local urban climate network MOCCA (MOnitoring the City's Climate and Atmosphere). The maximum hourly urban heat island (UHI) of 8.7 °C was noticed during the record-breaking 2019 heat wave. OTC was calculated with RayMan based on the observations from the MOCCA network and characteristics of the micro-environment which affect the estimated OTC conditions. The results show that cold stress is more apparent in Ghent during all seasons, except for summer. Downtown locations had more comfortable conditions on seasonal and annual level when compared to the rural location which had the most uncomfortable OTC conditions mostly due to cold stress. However, during the daytime period of heat waves, the open downtown and rural location were most frequently exposed to extreme heat stress, while the urban park in the sparsely built LCZ was the most comfortable area because it was able to effectively mitigate heat stress. This study illustrates the subtlety of the results of a thermal comfort study if one investigates both heat and cold stress on a yearly basis and during the extreme heat wave periods in a city with a moderate climate.
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•Analysis of urban-rural and intra-urban outdoor thermal comfort conditions in Ghent (Belgium).•Cold stress is more apparent in Ghent (Belgium) during all seasons, except in summer.•PET values over 50 °C reached during record-breaking July 2019 heat wave.•Urban park most comfortable during heat waves.•Daytime heat stress peaks at open locations, both in city and countryside.
In the light of climate change and burgeoning urbanization, heat loads in urban areas have emerged as serious issues, affecting the well-being of the population and the environment. In response to a ...pressing need for more standardised and communicable research into urban climate, the concept of local climate zones (LCZs) has been created. This concept aims to define the morphological types of (urban) surface with respect to the formation of local climatic conditions, largely thermal. This systematic review paper analyses studies that have applied the concept of LCZs to European urban areas. The methodology utilized pre-determined keywords and five steps of literature selection. A total of 91 studies were found eligible for analysis. The results show that the concept of LCZs has been increasingly employed and become well established in European urban climate research. Dozens of measurements, satellite observations, and modelling outcomes have demonstrated the characteristic thermal responses of LCZs in European cities. However, a substantial number of the studies have concentrated on the methodological development of the classification process, generating a degree of inconsistency in the delineation of LCZs. Recent trends indicate an increasing prevalence of the accessible remote-sensing based approach over accurate GIS-based methods in the delineation of LCZs. In this context, applications of the concept in fine-scale modelling appear limited. Nevertheless, the concept of the LCZ has proven appropriate and valuable to the provision of metadata for urban stations, (surface) urban heat island analysis, and the assessment of outdoor thermal comfort and heat risk. Any further development of LCZ mapping appears to require a standardised objective approach that may be globally applicable.
Urban overheating (due to climate change and urbanization) and COVID-19 are two converging crises that must be addressed in tandem. Fine-scale, place-based, people-centric biometeorological and ...behavioral data are needed to implement context-specific preventative measures such as mask-wearing. This study collected local biometeorological measurements in diverse urban spaces (square, urban park, river quay) in Novi Sad, Serbia on hot sunny summer days (27–30 August 2020) during the COVID-19 pandemic. Observations were supplemented by an online survey asking questions about thermal sensation, comfort, and concurrent protective behavior of the local population. Biometeorological measurements show that the main square in the city center was the most thermally uncomfortable area. According to the survey, it was also perceived as the least safe space to not contract the virus. The urban park was perceived as the most thermally comfortable area in the morning and during midday. It was also considered the safest urban space for outdoor activities. In the evening, the river quay was the most thermally comfortable area in the city. Intra-urban differences in Physiologically Equivalent Temperatures were highest during midday, while differences in air temperatures were highest in the evening. More than 70% of the respondents did not wear face masks when it was hot because of breathing issues and feeling warmer than without mask. Most people wearing a mask felt “slightly warm” in the morning and evening, while the majority of respondents felt “hot” during midday. Only 3% of the respondents felt comfortable while wearing a mask, while 97% experienced some degree of discomfort (from slight discomfort to very uncomfortable). Our study shows that fine scale temporal and spatial urban biometeorological data and population surveys should be included in decision-making processes during the pandemic to develop climate-sensitive health services that are place-based, people-centric, and facilitate planning towards green, resilient, and inclusive cities.
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•Heat and masks influence human thermal sensation, comfort, and behavior.•An urban park is most comfortable during the day, a river quay in the evening.•A sun-exposed urban square is the most uncomfortable area.•97% of residents feel uncomfortable while wearing a mask outdoors in hot weather.•The urban park is perceived as the safest outdoor space for not contracting COVID-19.
A comprehensive analysis of air temperature (
T
a
) dynamics in “local climate zones” (LCZs) of Novi Sad (Serbia) was based on measurements from 17 stations during 3 years. Hourly changes of
T
a
, ...cooling rates (
CR
), heating rates (
HR
), and urban heat island (UHI) intensity were assessed on seasonal and annual level and during heat wave (HW) and cold wave (CW) periods. Substantial differences are observed for minimum (
T
min
) and mean temperatures (
T
mean
) between LCZs. Two-phase nocturnal cooling was recognized with the first cooling phase characterized by intensive LCZ dependent cooling starting at 1–3 h before sunset and lasting until 3–4 h after sunset. The second cooling phase lasts until sunrise and is characterized by less intensive and LCZ nondependent cooling. The most intensive cooling (
CR
peak
) was observed in first cooling phase of HW and ranged from − 1.6 °C h
−1
in street canyon (LCZ 2) to − 3.9 °C h
−1
in forest (LCZ A). Furthermore, a new cooling indicator (
CR
total
) was introduced. Due to cooling differences, the most intensive UHI of 5.5 °C was noticed between LCZs 2 and A at sunset + 1 h during HW. Two-phase diurnal heating was also recognized in LCZs with the first heating phase characterized by intensive LCZ dependent heating starting at sunrise and lasting until 4–7 h afterwards. The most intensive heating (
HR
peak
) ranged from 2.0 °C h
−1
in street canyon to 3.0 °C h
−1
in industrial area (LCZ 8) during HW. The second heating phase lasts until sunset and is characterized by less intensive heating and smaller
HR
differences between LCZs.
In this study, air temperature and precipitation seasonality and their correlation with large-scale atmospheric circulations over the Sava River Basin (SRB), i.e., over the areas of Slovenia, ...Croatia, and Serbia, are analyzed. We used daily air temperature and precipitation measurements from 12 meteorological stations for the period from 1981 to 2010. In addition, mean (Ta), maximum (Tmax), and minimum (Tmin) daily temperatures and daily precipitation (P) were included in the analysis. Temperature values were correlated with atmospheric circulation patterns (ACPs), i.e., daily indices Arctic Oscillation (AO), North Atlantic Oscillation (NAO), and Mediterranean Oscillation (MO) for the same study period. The daily air temperature and precipitation data were obtained from European Climate Assessment & Dataset (ECA&D). The results generally show increasing trends in air temperatures, mainly during the spring and summer seasons, but also non-significant trends for precipitation. Moreover, the correlation results show no or weak influence of ACPs on seasonal air temperatures and precipitation, but the dominant effects differ by ACP type as well as at different seasonal levels. Among the selected ACPs, MO proved to be the most significant for the Sava River Basin.
Background
Nature-based solutions (NBS) in urban areas offer an opportunity to improve environmental conditions and to reduce CO
2
emissions towards establishing climate-neutral cities in the next ...few decades. Furthermore, the implementation of NBSs—vertical or horizontal green infrastructures on public facilities—could in particular improve both climate, including outdoor thermal conditions on a micro-scale (especially during the summer season) and the energy demand of buildings as well as save heating energy during the winter period.
Results
On both selected buildings, extensive green roofs were implemented as an NBS intervention. The analysed data were obtained using the monitoring systems (from 2019 to 2022) installed on two public buildings in Novi Sad (Republic of Serbia) and Osijek (Republic of Croatia), with a focus on climate/bioclimate characteristics and thermal transmission capacities. Four automatic weather stations (AWS) were used for microclimate monitoring, along with the heat flow meter (HFM) method, to measure the alterations in the thermal transmittance (
U
value) of a flat concrete roof before and after energy refurbishment and the installation of a green roof. The outcomes of this study show that the air temperatures (
Ta
) and globe temperatures (
Tg
) near the green roof are lower by 0–3 °C for
Ta
and by 0–16.5 °C for
Tg
than the values captured by the AWSs at other locations. An even more interesting fact is that the green roof has a constant cooling potential during tropical nights, and based upon this research, the cooling value is around 2 °C for
Tg
(the
Ta
value is not distinct). The thermal transmittance results show that more savings can be achieved by applying a green roof with an 8 cm thick substrate:
U
values decreased by 50–69%, as measured by two different heat flux sensors.
Conclusions
Nature-based solutions, such as the implementation of an extensive green roof, have positive effects on diverse aspects of urban environments and building energy savings, which are particularly evident in extreme seasons, both summer and winter. Applying the proposed monitoring and assessment system could help local communities in their efforts to reduce carbon-based emissions. This paper provides a good example of the implementation of NBSs on a local- and a micro-scale.
Climate change at the regional and local levels is forcing strong implementation of urban adaptation strategies related to climate-conscious urbanization and public health. Accordingly, the ...application of parameters that assess thermal stress in urban areas, such as outdoor thermal comfort (OTC) indices, is of paramount importance. As a contribution to this statement, long-term (1961–2020) datasets of daily OTC indices for the city of Banja Luka (Bosnia and Hercegovina) were used. Detailed temporal analysis using Physiologically Equivalent Temperature (PET), Universal Thermal Climate Index (UTCI), and Mean Radiant Temperature (Tmrt) was performed for (a) the entire research period, (b) the decadal level, and (c) defined heat/cold stress subcategories. The results show an intensive increase in extreme/strong heat days in the last 20 years, and the number of these days is five times higher than in the’70 s and’80 s. Decreasing tendencies are noticed in extreme/strong cold days towards the last two decades.
This data article describes two groups of datasets which capture, firstly - 10-minutes air temperature (Ta) and relative humidity (RH) data from 27 urban and non-urban sites over a period of 3.5 ...years covering 2014–2018; and secondly - hourly Ta data from 12 urban sites over a period of 2 years covering 2016 and 2017. Both datasets are from urban meteorological network located in the Novi Sad city (Serbia). These datasets have 2 different types of information in the collection: one type provides details about the monitoring sites at which the Ta and RH sensors are placed, while the second type contains Ta and RH data at all sensor locations. In all, the 10-minutes dataset contains about 185,000 instances of Ta and RH data, and the hourly datasets contain 17,544 instances of Ta data. The 10-minutes datasets were not quality controlled, but the hourly Ta data has been cleaned and gap-filled so there are 24 measures at each site for each day. There are multiple potential uses, where this data can be applied. It can provide insights in understanding intra-urban and inter-urban research, urban climate modeling on local or micro scales, heat-related public health investigations and urban environment inquiries. It can also be used in machine learning experiments, for example, to test the accuracy of classification algorithms or to build and validate spatio-temporal machine learning functions, either for classification purposes or for gap filling. These datasets are directly citable through its DOIs and available for download from the Zenodo platform or from the Fair Micromet Portal.
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