Urban heat/freshness islands, temperature differences and urban heat island intensity index 2020-2022

The data presented on this page concern the 2020-2022 mapping of temperature differences, the classification maps of these temperature differences (i.e. urban heat and freshness islands) and the map of the urban heat island intensity index. These different maps are detailed below:

- The map of __Temperature differences in °C__ represents the temperature difference in the city compared to a nearby forest. It was produced at the scale of the ecumene of Quebec (2021 census, 185,453 km2). This mapping, provided on a grid with a spatial resolution of 15 m, was carried out with a predictive machine learning model built on Landsat-8 satellite data provided by the *United States Geological Survey (USGS) * as well as from other geospatial variables such as hydrography and topography.

- The mapping of surface temperature difference classes, i.e. __Urban Heat and Cool Islands (ICFU) __ was carried out for * [population centers of the 2021 census] (https://www150.statcan.gc.ca/n1/pub/92-195-x/2021001/geo/pop/pop-fra.htm) * (CTRPOP) with at least 1,000 inhabitants and a density of at least 400 inhabitants per km2 to which is added a buffer zone of 2 km. It thus covers all major urban centers, i.e. 14,072 km2. The method for categorizing ICFUs is the ranking of predicted temperature differences for each population center into 9 levels. Classes 8 and 9 are considered __Urban Heat Islands__ and classes 1, 2 and 3 as __Urban Fresh Islands__. The interval values for each class and population center are shown in the production metadata file. Since surface temperatures were analyzed at the Quebec ecumene scale, but the classification intervals were calculated for each population center individually, the temperature differences grouped into the different classes vary from region to region. Thus, there are differences observed in the predicted temperature differences between North and South Quebec and according to urban realities. For example, a temperature difference of 2°C may be present in class 1 (cooler) in a population center located in southern Quebec, but may be present in class 9 (very hot) in a population center in northern Quebec. It is therefore important to interpret the identification of heat islands in relation to the relative temperature difference data produced at the Quebec ecumene scale. In addition to this map, the map of * [Temperature variations for the urbanization perimeters of the smallest municipalities 2020-2022] (https://www.donneesquebec.ca/recherche/dataset/variations-des-temperatures-pour-les-perimetres-d-urbanisation-des-plus-petites-municipalites) * covers all the urbanization perimeters that are not (or only partially) covered by the ICFU map. Thus, the two maps placed side by side allow a complete coverage of all population centers and urbanization perimeters in Quebec.

- The __Urban Heat Island Intensity Index (SUHII) map __ represents the*Surface Urban Heat Island Intensity* (SUHII) index. This index is calculated for each * [dissemination island] (https://www150.statcan.gc.ca/n1/pub/92-195-x/2021001/geo/db-id/db-id-fra.htm) * (ID) of Statistics Canada included in the * [2021 census population centers] (https://www150.statcan.gc.ca/n1/pub/92-195-x/2021001/geo/pop/pop-fra.htm) * () * (CTRPOP). It highlights areas with higher heat island intensity, by calculating a weighted average from temperature difference classes, giving more weight to the hottest classes. This weight is proportional to the class number (e.g. a class 9 surface is 9 times more important in the index than the same area with a class 1).

These maps as well as those of * [2013-2014] (https://www.donneesquebec.ca/recherche/dataset/ilots-de-chaleur-fraicheur-urbains-et-ecarts-de-temperature-relatifs-2013-2014) * are used for the * [Analysis of change between the mapping of heat/freshness islands 2013-2014 and 2020-2022] (https://www.donneesquebec.ca/recherche/dataset/analyse-de-changement-ilots-chaleur-fraicheur-et-indice-intensite-ilots-chaleur-urbains) *.

For more details on the creation of the various maps as well as their advantages, limitations and potential uses, consult the * [Technote] (https://www.donneesquebec.ca/recherche/dataset/ilots-de-chaleur-fraicheur-urbains-et-ecarts-de-temperature-relatifs-2020-2022/resource/285927d4-125e-443a-b5fb-e7c11515b617) * (simplified version) and/or the * [methodological report] (https://www.donneesquebec.ca/recherche/dataset/ilots-de-chaleur-fraicheur-urbains-et-ecarts-de-temperature-relatifs-2020-2022/resource/ef5f91cb-f6c9-48f4-ae06-bbfb3483e06e) * (version complete).

The production of this data was coordinated by the National Institute of Public Health of Quebec (INSPQ) and carried out by the forest remote sensing laboratory of the Center for Forestry Education and Research (CERFO), funded under the * [2013-2020 Climate Change Action Plan] (https://www.environnement.gouv.qc.ca/changementsclimatiques/plan-action.asp) * of the Quebec government entitled Le Québec en action vert 2020. 
**This third party metadata element was translated using an automated translation tool (Amazon Translate).**

Organization: Government and Municipalities of Québec | Gouvernement et municipalités du Québec