This paper seeks to extend the definition of a sub-centre beyond the usual definition as a place with significantly larger employment density that has an effect on the overall employment density of the nearby locations. Together with the previous conditions, it is suggested that it is necessary to include another which represents a structural element of an urban sub-system within the metropolitan configuration—that is, a place with intense spatial interaction with its hinterland. Therefore, a metropolitan area can be seen as one comprising urban sub-systems characterised by greater or lesser polycentrism. In this paper, a ‘bottom—up’ methodology based on commuter flows is proposed in order to detect metropolitan sub-centres. Using empirical data from the Metropolitan Region of Barcelona, the proposed methodology is tested, comparing its results with those of other commonly used methodologies (cut-offs, parametric and non-parametric models). The results suggest that the proposed methodology permits optimising the sub-centre delimitation process.

The objective of this study was to analyze the climate change experienced in Spain between 1971 and 2022 and to estimate the future climate (2050). The main objectives were as follows: (1) to analyze the temporal evolution of temperature from 1971 to the present, to quantify the warming process experienced in the case study and to evaluate the increase in extreme heat events (heatwaves); (2) to study the evolution of the precipitation regime to determine whether there is a statistically representative trend towards a drier climate and an increase in extreme precipitation; (3) to investigate the interaction between annual precipitation and the continuous increase in temperature; and (4) to estimate the future climate scenario for mainland Spain and the Balearic Islands towards 2050, analyzing the trends in land aridity and predicting a possible change from a Mediterranean climate to a warm steppe climate, according to the Köppen classification. The aim of this study was to test the hypothesis that the increase in temperature resulting from the global warming process implies a tendency towards progressive drought. Given the extreme annual variability of the climate, in addition to the ordinary least squares methodology, the techniques mainly used in this study were the Mann–Kendall test and the Kendall–Theil–Sen (KTS) regression. The Mann–Kendall test confirmed the very high statistical significance of the relationship between precipitation (RR) and maximum temperature (TX). If the warming trend experienced in recent years (1971–2022) continues, it is foreseeable that, by 2050, there will be a reduction in precipitation in Spain of between 14% and 23% with respect to the precipitation of the reference period (understood as the average between 1971 and 2000). Spain’s climate is likely to change from Mediterranean to warm steppe in the Köppen classification system (from “C” to “B”).

One of the challenges of heritage cities is sustainably balancing mass tourism and the daily life of its residents. Urban policies can modulate the impact of tourism through regulations focusing on areas with outstanding visitor pressure, which must consequently be delimited accurately and objectively. Within a traditionally data-scarce discipline, urban practitioners can currently employ a wide range of tracking technologies, but because of their limitations can also greatly benefit from new sources of data from social media. Using Barcelona as a testbed, a methodology is presented to identify and visualize hot spots of visitor activity using more than a million public geotagged images collected from the Flickr photo-sharing community. Multiple complementary visualization approaches are discussed that are suitable for different scales of analysis, from global to sub-block resolution. The presented methodology is firmly grounded in a well-established spatial statistics framework, adapted to a “big data” environment, to extract knowledge from social media. It is designed to generalize to other urban settings, providing substantial advantages over other surveying methods in terms of cost-efficiency, scalability, and accuracy, while capturing the behavior of a larger number of participants and covering more extensive areas or temporal spans.

This article presents a methodology to process information from a Terrestrial Laser Scanner (TLS) from three dimensions (3D) to two dimensions (2D), and to two dimensions with a color value (2.5D), as a tool to document and analyze heritage buildings. Principally focused on the loss of material in stone, this study aims at creating an evaluation method for loss control, taking into account the state of conservation of a building in terms of restoration, from studying the pathologies, to their identification and delimitation. A case study on the Cathedral of the Seu Vella de Lleida was completed, examining the details of the stone surfaces. This cathedral was affected by military use, periods of abandonment, and periodic restorations.

The aim of this research is to analyze the influence of park design and location on their cooling effect during summer daytime in Barcelona. Spatial analytical methods, utilizing the land surface temperature data from the Landsat 8 satellite, were employed to assess the intensity and spatial extent of the Park Cool Island (PCI) in 86 parks over four consecutive years. The study investigated the influence of factors such as the proportion of green land cover, park shape, and surrounding characteristics on these PCI indicators using bivariate correlation and multiple linear regression analysis. Results revealed that 84 parks exhibited a positive cooling effect on their urban surroundings during the studied years, whereas the remaining parks showed no PCI. The statistical analysis indicated that these results are associated with the microclimatic uncertainty caused by the diverse relationships between the proportion of natural vegetated or pervious surfaces and the built spaces within the parks, proposed by the administration aiming to accommodate civic, cultural, and recreational usage. In conclusion, we discuss the parameters for modeling the interaction between park design and their urban surroundings in the context of climatic considerations. This information is crucial for leveraging urban parks as spaces that can mitigate the urban heat island effect while preserving their social value as community public spaces.

The urban climate literature has highlighted the remarkable prominence of nighttime UHI phenomenon. During nighttime the UHI effects become more evident due to the greater thermal inertia of the materials used in urban fabric. It is during the night when the heat accumulated in urban materials, especially in contexts of heat waves, can generate significant health risks. The low cooling capacity of urban construction materials negatively affects the comfort and the health of urban dwellers. However, and despite the great importance of night stress due to heat, the study of night UHIs is still underdeveloped. In this context, this paper aims to determine nighttime LST contrasting Landsat's very limited nighttime images with daytime ones. The example developed refers to heat wave situations during the summer 2015. The case study is the Metropolitan Area of Barcelona (35 municipalities, 636 km², 3.3 million inhabitants).