Urban Heat Island Formation in Greater Cairo: Spatio-Temporal Analysis of Daytime and Nighttime Land Surface Temperatures along the Urban–Rural Gradient

Analysis of Long Time Series of Summer Surface Urban Heat Island under the Missing-Filled Satellite Data Scenario

Surface urban heat islands (SUHIs) are mostly an urban ecological issue. There is a growing demand for the quantification of the SUHI effect, and for its optimization to mitigate the increasing possible hazards caused by SUHI. Satellite-derived land surface temperature (LST) is an important indicator for quantifying SUHIs with frequent coverage. Current LST data with high spatiotemporal resolution is still lacking due to no single satellite sensor that can resolve the trade-off between spatial and temporal resolutions and this greatly limits its applications. To address this issue, we propose a multiscale geographically weighted regression (MGWR) coupling the comprehensive, flexible, spatiotemporal data fusion (CFSDAF) method to generate a high-spatiotemporal-resolution LST dataset. We then analyzed the SUHI intensity (SUHII) in Chengdu City, a typical cloudy and rainy city in China, from 2002 to 2022. Finally, we selected thirteen potential driving factors of SUHIs and analyzed the relation between these thirteen influential drivers and SUHIIs. Results show that: (1) an MGWR outperforms classic methods for downscaling LST, namely geographically weighted regression (GWR) and thermal image sharpening (TsHARP); (2) compared to classic spatiotemporal fusion methods, our method produces more accurate predicted LST images (R2, RMSE, AAD values were in the range of 0.8103 to 0.9476, 1.0601 to 1.4974, 0.8455 to 1.3380); (3) the average summer daytime SUHII increased form 2.08 °C (suburban area as 50% of the urban area) and 2.32 °C (suburban area as 100% of the urban area) in 2002 to 4.93 °C and 5.07 °C, respectively, in 2022 over Chengdu City; and (4) the anthropogenic activity drivers have a higher relative influence on SUHII than other drivers. Therefore, anthropogenic activity driving factors should be considered with CO2 emissions and land use changes for urban planning to mitigate the SUHI effect.

Spatiotemporal Thermal Variations in Moroccan Cities: A Comparative Analysis

This study examines the Land Surface Temperature (LST) trends in eight key Moroccan cities from 1990 to 2020, emphasizing the influential factors and disparities between coastal and inland areas. Geographically weighted regression (GWR), machine learning (ML) algorithms, namely XGBoost and LightGBM, and SHapley Additive exPlanations (SHAP) methods are utilized. The study observes that urban areas are often cooler due to the presence of urban heat sinks (UHSs), more noticeably in coastal cities. However, LST is seen to increase across all cities due to urbanization and the degradation of vegetation cover. The increase in LST is more pronounced in inland cities surrounded by barren landscapes. Interestingly, XGBoost frequently outperforms LightGBM in the analyses. ML models and SHAP demonstrate efficacy in deciphering urban heat dynamics despite data quality and model tuning challenges. The study's results highlight the crucial role of ongoing urbanization, topography, and the existence of water bodies and vegetation in driving LST dynamics. These findings underscore the importance of sustainable urban planning and vegetation cover in mitigating urban heat, thus having significant policy implications. Despite its contributions, this study acknowledges certain limitations, primarily the use of data from only four discrete years, thereby overlooking inter-annual, seasonal, and diurnal variations in LST dynamics.

Identifying the dominant impact factors and their contributions to heatwave events over mainland China

The heatwave frequency and intensity have significantly changed as the climate warms and human activities increase, which poses a potential risk to human society. However, the impact factors that determine the change of heatwave events remain unclear. Here, we estimated the heatwave events based on data from 2474 in-suit gauges during 1960-2018 at daily scale in China. Besides, we explored possible drivers and their contributions to the change of heatwave based on correlation analysis, multiple linear regression (MLR), and random forest (RF) in different subregions of China. The results show that the temporal changes of all heatwave metrics exhibit significant differences between the period 1960-1984 and the period 1985-2019. Spatially, the heatwave frequency and duration significant increase in the southern China (S), eastern arid region (EA), northeastern China (NE), Qinghai-Tibet region (QT) and western arid and semi-arid region (WAS). The occurrence of the first heatwave event in a year tends to be earlier in S, NE, EA, WAS, and QT than before. Based on the regression modelling and RF, human activities play an important role in heatwave intensity in all subregions of China. For heatwave frequency, urbanization generate a dominant influence in NE, EA, and QT, with relative contributions (RC) ranging from 32.8 % to 38.9 %. Long-term climate change exerts the dominant influence in C, N, and S. Moreover, the first day of the yearly heatwave event (HWT) in NE is significantly influenced by climate change, with RC of 33.9 % for temperature variation (TEM). Our findings could provide critical information for understanding the causes of heatwave across different regions of China in the context of rapid urbanization and climate change.

Quantifying the spatial pattern of urban heat islands and the associated cooling effect of blue-green landscapes using multisource remote sensing data

Surface urban heat islands (SUHIs) are a global concern. Although their spatial pattern and the cooling effect of blue-green landscapes have been documented, exploring more accurate and quantitative results is still necessary. For Hangzhou, we combined nighttime light (NTL) data with LST images to investigate the spatial morphology of SUHIs and analyze the cooling effect of blue-green landscapes. The radiative transfer equation (RTE) method was used to derive the land surface temperature (LST). Then, based on the unique feature of Luojia1-01 NTL data, the concentric zone model (CZM) was proposed to depict the urban spatial structure. The CZM was applied to construct a number of equal-area concentric belts along the urban-rural gradient to determine the SUHI range and the corresponding blue-green landscape cooling effects. Finally, local Moran's I indices were adopted to identify the cold-hot spots of the SUHI and the relationship with land use. The minimum, average and maximum LSTs were 21.81 °C, 32.79 °C and 44.79 °C, respectively. Additionally, 59.16 % of the study area was affected by the SUHI, and the mean LST inside the SUHI was 36.4 °C, clearly higher than that of the rural area. The SUHI hotpots were clustered in regions with intensive human activities, forming archipelagos. Due to the different blue-green landscape densities, the cooling capacity had spatial heterogeneity in different urban rural belts (URBs), and the cooling capacity of URB₁₆ was approximately 71 times that of URB₁. The cooling efficiency increased with blue-green landscape density in general; hence, blue-green landscape density thresholds of 40 % and 70 % were recommended in the urban planning of different urban function zones. Relating the pattern of NTL data to LST images provide meaningful insight into the spatial pattern of SUHIs and the optimization of urban planning.

Urban ventilation corridors and spatiotemporal divergence patterns of urban heat island intensity: a local climate zone perspective

Urban ventilation corridors introduce fresh air into urban interiors and improve urban livability, while mitigating the urban heat island (UHI) effect. However, few studies have assessed the impact of urban ventilation corridors on UHI intensity (UHII) from the perspective of the local climates of different cities. Therefore, this study integrated multisource data to construct ventilation corridors from the perspective of local climate zone (LCZ) and analyzed its impact on UHII. The results showed the following: (1) the average UHII of constructed LCZs was higher than that of natural LCZs, among which the building type LCZ10 (heavy industry) had the highest intensity (5.77 °C); (2) in extracted ventilation corridors, the pixel number of natural LCZs was substantially larger than that of constructed LCZs, among which LCZE (bare soil/paved) was the largest; and (3) for natural LCZs, the average UHII of each LCZ was lower within the ventilated corridors than within the non-ventilated corridors (except for LCZG [water]), with the UHII of LCZB (scattered trees) exhibiting the greatest mitigation effect. Quantitative research on the composition and function of ventilation corridors can not only assess the ability of ventilation corridors to mitigate UHIs, but also provide a reference for urban ventilation corridor planning.

Workers’ Satisfaction vis-à-vis Environmental and Socio-Morphological Aspects for Sustainability and Decent Work

This study examines worker satisfaction vis-à-vis outdoor places in terms of their environmental and socio-morphological aspects. Numerous studies have considered decent work as the eighth goal of sustainable development. However, it is worth investigating outdoor workers’ satisfaction with a view to the practical design of the surrounding context that supports their work in outdoor places. Using bibliometric analysis, this study investigates possible approaches toward providing decent work in a public place in Cairo as a case study, focusing on outdoor workers’ satisfaction. In the bibliometric analysis, this study used query settings in the Scimago database to search for manuscripts published in the previous five years. The result yielded 195 manuscripts that were filtered down to 50 manuscripts and then grouped using VOSviewr Software. Environmental noise and heat assessment analyses were performed using noise level measurements, remote sensing, and the Grasshopper platform. Further, we conducted an ethnographic study employing 77 participant observations. The results show that work hours and time affect worker satisfaction, as do environmental conditions, particularly noise and heat. However, unexpected findings from participant observation in this study do not accord with findings in other scholarly sources, where other observers find workers neither satisfied nor dissatisfied with the spatial morphology in the case study. Per this study, the alignment of worker satisfaction with convenient socio-morphological tangible elements of the workplace and with other environmental aspects should be attained in both specified replicable methods to engender decent work for outdoor workers.