Review of methods for retrieving urban heat islands

Urban heat island is one of the alarming phenomena that exacerbate urban microclimate. Measuring this magnitude in time and space is crucial to obtain a general overview of the thermal environment at a mul- tiscale level ranging from the district scale to the city scale including its outskirts areas. These measure- ments allow the detection of black spots that can be used as a reference to fight against thermal anomalies resulting from anthropogenic causes and then to develop metropolitan areas more resilient to microclimate modifications, thus ensuring a real sustainable development of the environment and the territory. The main purpose of this paper is to provide the state of the art of different techniques and methods that have been developed to retrieve the spatial distribution of different types of urban heat island implemented in the urban climatology field. These different techniques are regrouped into three main categories namely In -Situ measurements, Remote Sensing observation methods and the modeling approach and allow to provide two types of urban heat island: the atmospheric urban heat island that includes the canopy and boundary layers; and the surface urban heat island. This paper provides also a detailed benchmarking of the different approaches of urban heat island modeling and gives a general overview of the strengths and weaknesses of each technique. (C) 2020 Elsevier Ltd. All rights reserved. Selection and peer -review under responsibility of the scientific committee of The Third International Conference on Materials and Environmental Science.