Mapping Local Climate Zones for a Worldwide Database of the Form and Function of Cities (original) (raw)
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Sustainable Development and Planning XI
The effect of rapid urbanization on the urban climate has been studied in different cities worldwide. Facing the intricate impacts of changes in urban climate on inhabitants' wellbeing and environment, city planners are increasingly investigating climate determinants in their urban planning decisions. In Alexandria, Egypt, the urban morphology is characterized by high diversity that is expected to increase due to plans for future urban expansions. It is assumed that this diversity entails a variation in both physical and climatological characteristics of its urban canopy. In this context, climate-based classification of urban and rural areas, such as local climate zones could be used to support planning decisions. It assists in detecting the urban heat island and in documenting the urban surface properties, thus ensuring better decisions concerning the configuration of the built environment. This research adopts the method of the World Urban Database and Access Portal Tools, which employs a semi-automated classification of local climate zones. It combines pixel-based supervised classification of satellite imageries and local knowledge of the microscale built-up characteristics. While the method could be considered of average accuracy in terms of classification, training areas delineation and class interpretation, it gains specific importance due to its global implementation. This research presents a classification framework for the local climate zones based on incorporating several tools of extracting urban morphological characteristics. The study approach includes the following steps: (1) Identifying the morphological properties of the existing local climate zones types and subtypes using the available remotely sensed and geospatial data, (2) Classifying and digitizing the training areas of local climate zones classes from Google Earth satellite imageries, and (3) Automating the classification using the System for Automated Geoscientific Analysis. The introduced approach produces an enhanced local climate zones map that helps in identifying urban and natural features using their physical setting.
There is a scientific consensus on the need for spatially detailed information on urban landscapes at a global scale. These data can support a range of environmental services, since cities are places of intense resource consumption and waste generation and of concentrated infrastructure and human settlement exposed to multiple hazards of natural and anthropogenic origin. In the face of climate change, urban data are also required to explore future urbanization pathways and urban design strategies in order to lock in long-term resilience and sustainability, protecting cities from future decisions that could undermine their adaptability and mitigation role. To serve this purpose, we present a 100 m-resolution global map of local climate zones (LCZs), a universal urban typology that can distinguish urban areas on a holistic basis, accounting for the typical combination of micro-scale land covers and associated physical properties. The global LCZ map, composed of 10 built and 7 natural land cover types, is generated by feeding an unprecedented number of labelled training areas and earth observation images into lightweight random forest models. Its quality is assessed using a bootstrap crossvalidation alongside a thematic benchmark for 150 selected functional urban areas using independent global and open-source data on surface cover, surface imperviousness, building height, and anthropogenic heat. As each LCZ type is associated with generic numerical descriptions of key urban canopy parameters that regulate atmospheric responses to urbanization, the availability of this globally consistent and climate-relevant urban description is an important prerequisite for supporting model development and creating evidence-based climatesensitive urban planning policies. This dataset can be downloaded from https://doi.org/10.5281/zenodo.6364594 (Demuzere et al., 2022a). 1 Introduction Cities are at the forefront of global climate change science owing to their emissions of greenhouse gases and their exposure to projected hazards, such as sea-level rise and climate warming (IPCC, 2022). As a result, they are the focus of mitigation and adaptation policies and, as they have governance structures in place, are an ideal scale to affect change. The crucial role that cities can play in this arena is recognized at the international level: the new United Nations Agenda and the 11th Sustainable Development Goal focus on urban resilience, climate, and environment sustainability of cities, two of the four challenges identified by the World Meteorological Organisation (WMO) World Weather Research
2016
Given rapid population growth and urbanization, it might be apt to characterize this and the last few centuries as the Urban Epoch of the Anthropocene, Earth's most recent and human influenced geologic time period (Crutzen and Stoermer, 2000). Human activities in this urban epoch have enormous influence and consequence on current and future climate. Urbanization is unavoidable and without proper management can lead to disastrous, extreme, and unexpected events. We now design powerful computer models for use as tools applicable on a global scale for guidance on climate change. More than half of the planet’s population resides in urban areas and the degree of urbanization is projected to increase rapidly; thus it is important that modeling tools be available and suitable for urban applications to develop rational urbanization approaches and guidance to mitigate deleterious effects of urbanization and supporting design for urban resiliency. The form and function of structures in ur...
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2016
Although more than half of the Earth’s population live in urban areas, we know remarkably little about most cities and what we do know is incomplete (lack of coverage) and inconsistent (varying definitions and scale). While there have been considerable advances in the derivation of a global urban mask using satellite information, the complexity of urban structures, the heterogeneity of materials, and the multiplicity of spectral properties have impeded the derivation of universal urban structural types (UST). Further, the variety of UST typologies severely limits the comparability of such studies and although a common and generic description of urban structures is an essential requirement for the universal mapping of urban structures, such a standard scheme is still lacking. More recently, there have been two developments in urban mapping that have the potential for providing a standard approach: the Local Climate Zone (LCZ) scheme (used by the World Urban Database and Access Portal...
Local Climate Zones (LCZ) is a new methodology to improve the characterization of urban station localization. This new methodology has great potential to prepare urban climate maps and improve the way of communicating the results of urban climate research to urban planners. These kinds of maps are a highly accurate way to inform of the application of new mitigation strategies related to the climatic and construction characteristics of a city. Tandil is a mid city located in Buenos Aires province in Argentina. It has a transition temperate climate and is surrounded by the center of Tandilia’s Hill System from west to south. It takes up the top and middle basin of river Langueyú. The city’s population is of 116,916 inhabitants and it has a diversified economy with a well developed service sector. This is the first study in it’s kind in Argentina. The preparation of the LCZ map of Tandil takes into account such climatic information as temperature, humidity, precipitation, wind and comf...
Influence of neighbourhood information on ‘Local Climate Zone’ mapping in heterogeneous cities
International Journal of Applied Earth Observation and Geoinformation, 2017
Local climate zone (LCZ) mapping is an emerging field in urban climate research. LCZs potentially provide an objective framework to assess urban form and function worldwide. The scheme is currently being used to globally map LCZs as a part of the World Urban Database and Access Portal Tools (WUDAPT) initiative. So far, most of the LCZ maps lack proper quantitative assessment, challenging the generic character of the WUDAPT workflow. Using the standard method introduced by the WUDAPT community difficulties arose concerning the built zones due to high levels of heterogeneity. To overcome this problem a contextual classifier is adopted in the mapping process. This paper quantitatively assesses the influence of neighbourhood information on the LCZ mapping result of three cities in Belgium: Antwerp, Brussels and Ghent. Overall accuracies for the maps were respectively 85.7 ± 0.5, 79.6 ± 0.9, 90.2 ± 0.4%. The approach presented here results in overall accuracies of 93.6 ± 0.2, 92.6 ± 0.3 and 95.6 ± 0.3% for Antwerp, Brussels and Ghent. The results thus indicate a positive influence of neighbourhood information for all study areas with an increase in overall accuracies of 7.9, 13.0 and 5.4%. This paper reaches two main conclusions. Firstly, evidence was introduced on the relevance of a quantitative accuracy assessment in LCZ mapping, showing that the accuracies reported in previous papers are not easily achieved. Secondly, the method presented in this paper proves to be highly effective in Belgian cities, and given its open character shows promise for application in other heterogeneous cities worldwide.
Mapping Europe into local climate zones
PLOS ONE
Cities are major drivers of environmental change at all scales and are especially at risk from the ensuing effects, which include poor air quality, flooding and heat waves. Typically, these issues are studied on a city-by-city basis owing to the spatial complexity of built landscapes, local topography and emission patterns. However, to ensure knowledge sharing and to integrate local-scale processes with regional and global scale modelling initiatives, there is a pressing need for a worldwide database on cities that is suited for environmental studies. In this paper we present a European database that has a particular focus on characterising urbanised landscapes. It has been derived using tools and techniques developed as part of the World Urban Database and Access Portal Tools (WUDAPT) project, which has the goal of acquiring and disseminating climate-relevant information on cities worldwide. The European map is the first major step toward creating a global database on cities that can be integrated with existing topographic and natural land-cover databases to support modelling initiatives.
Modelling the urban climate using a local governmental geo-database
Meteorological Applications, 2007
In this study, local government digital spatial data are used to describe urban geometry and analyse spatial variations of the urban climate within the central areas of Göteborg, Sweden. A high-resolution raster digital elevation model (1 m pixel resolution) consisting of building structures and ground heights is derived from a local government geodatabase, as well as land use patterns and artificial heat sources. Parameters such as the sky view factor (SVF) and daily averages of solar radiation are calculated. Results obtained from the model are compared with intra-urban air temperature variations which are derived from mobile measurements, as well as surface temperature variations derived from thermal infrared images. Results show that high-resolution digital elevation models in raster format are very useful sources of data for the investigation of intra-urban temperature variations. Results also show that the areal mean of SVF correlates with intra-urban air temperature variations to a higher degree than SVF that is taken from a point source location. The correlation between the modelled SVF and surface temperature is high during both spring and winter. Adding information about daily averages of global radiation for the spring measurement causes the correlation between SVF and surface temperature variations to increase.
Urban Climate
Cities are particularly vulnerable to meteorological hazards because of the concentration of population, goods, capital stock and infrastructure. Urban climate services require multi-disciplinary and multi-sectorial approaches and new paradigms in urban climate modelling. This paper classifies the required urban input data for both mesoscale state-of-the-art Urban Canopy Models (UCMs) and microscale Obstacle Resolving Models (ORM) into five categories and reviews the ways in which they can be obtained. The first two categories are (1) land cover, and (2) building morphology. These govern the main interactions between the city and the urban climate and the Urban Heat Island. Interdependence between morphological parameters and UCM geometric hypotheses are discussed. Building height, plan and wall area densities are recommended as the main input variables for UCMs, whereas ORMs require 3D building data. Recently, three other categories of urban data became relevant for finer urban studies and adaptation to climate change: (3) building design and architecture, (4) building use, anthropogenic heat and socio-economic data, and (5) urban vegetation data. Several methods for acquiring spatial information are reviewed, including remote sensing, geographic information system (GIS) processing from administrative cadasters, expert knowledge and crowdsourcing. Data availability, data harmonization, costs/efficiency tradeoffs and future challenges are then discussed.