scholarly journals An Application of the LCZ Approach in Surface Urban Heat Island Mapping in Sofia, Bulgaria

Atmosphere ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1370
Author(s):  
Stelian Dimitrov ◽  
Anton Popov ◽  
Martin Iliev
Keyword(s):  
Surface Temperature ◽  
Urban Morphology ◽  
Time Interval ◽  
Research Approach ◽  
Average Intensity ◽  
Heat Island ◽  
Average Surface ◽  
Average Surface Temperature ◽  
Surface Temperatures ◽  
Local Climate Zones

This article presents the results of the thermal survey of the capital of Bulgaria (Sofia) carried out in August 2019, with the application of an unmanned aerial system (UAS). The study is based on the concept of local climate zones (LCZs), taking into account the influence of the features of land use/land cover and urban morphology on the urban climate. The basic spatial units used in the study are presented in the form of a regular grid consisting of 3299 cells with sides of 250 ´ 250 m. A total of 13 types of LCZs were identified, of which LCZs 6, 5, 8, 4, D, and A form the largest share. In the thermal imaging of the surface, a stratified sampling scheme was applied, which allowed us to select 74 cells, which are interpreted as representative of all cells belonging to the corresponding LCZ in the urban space. The performed statistical analysis of the thermal data allowed us to identify both the most thermally loaded zones (LCZs 9, 4, and 5) and the cells forming Urban Cool Islands (mainly in LCZs D and C). The average surface temperature in Sofia during the study period (in the time interval between 8:00 PM and 10:00 PM) was estimated at 20.9 °C, and between the different zones it varied in the range 17.2–25.1 °C. The highest maximum values of LST (27.9–30.6 °C) were registered in LCZ 4 and LCZ 5. The relation between the spatial structure of the urban thermal patterns and urban surface characteristics was also analyzed. Regression analysis confirmed the hypothesis that as the proportion of green areas increases, surface temperatures decrease, and, vice versa, as the proportion of built-up and impermeable areas increases, surface temperatures increase. A heat load map (via applying a z-transformation to standardize the temperature values), a map of the average surface temperature, and a map of the average intensity of the heat island on the surface were generated in the GIS environment. The results of the study adequately reflect the complex spatial model of the studied phenomenon, which gives grounds to conclude that the research approach used is applicable to similar studies in other cities.

scholarly journals LINKING THE LOCAL CLIMATE ZONES AND LAND SURFACE TEMPERATURE TO INVESTIGATE THE SURFACE URBAN HEAT ISLAND, A CASE STUDY OF SAN ANTONIO, TEXAS, U.S.

2018 ◽  
Vol IV-3 ◽  
pp. 277-283 ◽  
Author(s):  
Chunhong Zhao
Keyword(s):  
Surface Temperature ◽  
Urban Heat Island ◽  
Land Surface Temperature ◽  
Land Surface ◽  
San Antonio ◽  
Heat Island ◽  
Climate Zones ◽  
Local Climate ◽  
Local Climate Zones ◽  
Urban Heat

The Local Climate Zones (LCZs) concept was initiated in 2012 to improve the documentation of Urban Heat Island (UHI) observations. Despite the indispensable role and initial aim of LCZs concept in metadata reporting for atmospheric UHI research, its role in surface UHI investigation also needs to be emphasized. This study incorporated LCZs concept to study surface UHI effect for San Antonio, Texas. LCZ map was developed by a GIS-based LCZs classification scheme with the aid of airborne Lidar dataset and other freely available GIS data. Then, the summer LST was calculated based Landsat imagery, which was used to analyse the relations between LST and LCZs and the statistical significance of the differences of LST among the typical LCZs, in order to test if LCZs are able to efficiently facilitate SUHI investigation. The linkage of LCZs and land surface temperature (LST) indicated that the LCZs mapping can be used to compare and investigate the SUHI. Most of the pairs of LCZs illustrated significant differences in average LSTs with considerable significance. The intra-urban temperature comparison among different urban classes contributes to investigate the influence of heterogeneous urban morphology on local climate formation.

scholarly journals Influence of Urban Scale and Urban Expansion on the Urban Heat Island Effect in Metropolitan Areas: Case Study of Beijing–Tianjin–Hebei Urban Agglomeration

2020 ◽  
Vol 12 (21) ◽  
pp. 3491 ◽  
Author(s):  
Mingxing Chen ◽  
Yuan Zhou ◽  
Maogui Hu ◽  
Yaliu Zhou
Keyword(s):  
Climate Change ◽  
Surface Temperature ◽  
Urban Heat Island ◽  
Urban Expansion ◽  
Urban Agglomeration ◽  
Heat Island ◽  
Average Surface ◽  
Island Effect ◽  
Urban Heat ◽  
The Relationship

Global large-scale urbanization has a deep impact on climate change and has brought great challenges to sustainable development, especially in urban agglomerations. At present, there is still a lack of research on the quantitative assessment of the relationship between urban scale and urban expansion and the degree of the urban heat island (UHI) effect, as well as a discussion on mitigation and adaptation of the UHI effect from the perspective of planning. This paper analyzes the regional urbanization process, average surface temperature variation characteristics, surface urban heat island (SUHI), which reflects the intensity of UHI, and the relationship between urban expansion, urban scale, and the UHI in the Beijing–Tianjin–Hebei (BTH) urban agglomeration using multi-source analysis of data from 2000, 2005, 2010, and 2015. The results show that the UHI effect in the study area was significant. The average surface temperature of central areas was the highest, and decreased from central areas to suburbs in the order of central areas > expanding areas > rural residential areas. From the perspective of spatial distribution, in Beijing, the southern part of the study area, the junction of Tianjin, Langfang, and Cangzhou are areas with intense SUHI. The scale and pace of expansion of urban land in Beijing were more than in other cities, the influencing range of SUHI in Beijing increased obviously, and the SUHI of central areas was most intense. The results indicate that due to the larger urban scale of the BTH urban agglomeration, it will face a greater UHI effect. The UHI effect was also more significant in areas of dense distribution in cities within the urban agglomeration. Based on results and existing research, planning suggestions are proposed for central areas with regard to expanding urban areas and suburbs to alleviate the urban heat island effect and improve the resilience of cities to climate change.

An Integrated Model of Global Warming and Policy Making

2011 ◽  
Author(s):  
Zheming Zhang ◽  
Ramesh Agarwal
Keyword(s):  
Global Warming ◽  
Surface Temperature ◽  
Co2 Emissions ◽  
General Circulation ◽  
Co2 Concentration ◽  
Integrated Model ◽  
Co2 Mitigation ◽  
Average Surface ◽  
Global Average ◽  
Average Surface Temperature

This paper describes a simple integrated model of global warming due to anthropogenic CO2 emissions, which can help the policy makers in considering various CO2 mitigation strategies. First, the constant airborne fraction model is generalized to establish relationship between CO2 emissions and CO2 concentration in the atmosphere which is then used to determine the global average surface temperature using the Oglesby and Saltzman’s general circulation model. Using these simple relationships, the forecast for CO2 emissions, CO2 concentration and average global surface temperature is made for years 2030 and 2050 under Business as Usual (BAU) scenario. In order to achieve an acceptable target increase in global average surface temperature, several simple CO2 mitigation approaches, proposed by Socolow and Lam, are included in the integrated model.

On the strongly negative cloud feedback over the satellite period implied by observational SST reconstructions

2021 ◽  
Author(s):  
Stephan Fueglistaler ◽  
Levi Silvers
Keyword(s):  
Surface Temperature ◽  
General Circulation ◽  
Deep Convection ◽  
Historical Period ◽  
Surface Temperature Change ◽  
Average Surface ◽  
Global Average ◽  
Coupled Gcm ◽  
Average Surface Temperature ◽  
Second Mode

<p>Clouds strongly modulate Earth's radiative budget, and uncertainties in numerical model simulations of the global cloud field contribute substantially to uncertainties in future warming. In coupled atmosphere-ocean General Circulation Model (GCM) simulations, the global cloud field and its radiative effect are well correlated with global average surface temperature. However, GCM simulations with prescribed Sea Surface Temperatures (SSTs) from observational SST reconstructions over the historical period show time-varying relationships between the cloud field and average surface temperature (known as the "pattern effect"). We show that CERES/EBAF observational data confirms the presence of a second mode (in addition to mean SST) in particular in low cloud amount (and correspondingly SWCRE) that is consistent with variations in tropical atmospheric stability in ERA-Interim reanalysis data. This second mode in observations is tied to ENSO, and evolves in quadrature to ENSO indexes. It arises from differences in surface temperature change between regions of tropical deep convection and the tropical (or global) average. In contrast to the multidecadal trends over the full historical period, trends in this second mode since the year 2000 are small. The PCMDI/AMIPII SSTs recommended for CMIP6 stand out as having the largest trend over the full historical period. Different SST reconstructions agree on a trend over the satellite period - specifically the 1980s-90s - that is much larger than what coupled GCM simulations show: In forced coupled GCM simulations the regions of deep convection warm order 10% more than the tropical average, whereas over the satellite period the amplification is order +50%  in the AMIP simulations and in estimates using rainfall observations to identify regions of deep convection.</p>

An Analysis of Various Cooling Liquids in a Two-Cylinder Single-Stage Piston Hybrid Power Machine with Fluid Flow Due to Vacuum at Suction Based on Experimental Results

2020 ◽  
pp. 40-49
Author(s):  
V.E. Shcherba ◽  
G.S. Averyanov ◽  
S.A. Korneev ◽  
S.V. Korneev ◽  
A.Y. Ovsyannikov ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Surface Temperature ◽  
Distilled Water ◽  
Average Surface ◽  
Working Chamber ◽  
Hybrid Power ◽  
Average Surface Temperature ◽  
Transmission Oil ◽  
Power Machine ◽  
Hybrid Power Machine

This paper examines the use of various types of cooling liquids in a two-cylinder single-stage piston hybrid power machine with fluid flow due to vacuum at suction. Liquids with various basic thermal properties were used as working fluids: distilled water, antifreeze, and transmission oil. Specific heat capacities and dynamic viscosities of these liquids differed from 2 to 10 times. The experimental studies showed that the greatest cooling effect on the cylinder-piston group was observed when using distilled water, and the least — when using transmission oil. The average surface temperature of the working chamber when cooled with water was minimal in the range of 330–340 K. The average surface temperature of the working chamber when cooled with transmission oil was maximum and ranged from 345 to 355 K, i. e. it was about 15 K higher than when cooled with water. The average surface temperature of the working chamber when cooled with antifreeze occupied an intermediate position between the average temperatures of the working chamber when cooled with water and that with transmission oil and was in the range of 335–345 K, i. e. about 5 K higher than when cooled with water.

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