Crowdsourced vehicle data trace the contours of dangerous city temperatures
Schmidt's efforts were the first to map a city's "Islands" of heat in a "Sea" of lower-temperature surroundings.
Their approach uses thermometers in Internet-connected personal cars to map how temperatures can vary over just a few city blocks; such data could help urban planners develop heat-mitigation policies in places without access to sophisticated instrumentation.
Urban heat islands occur when natural land cover is replaced with asphalt, concrete, steel, or other materials that absorb and retain more heat than their surroundings.
Heat islands also affect a city's air quality by influencing humidity and how pollutants get distributed in the atmosphere.
"With the increase of extreme events like heat waves, city planners need to rethink how urban spaces are designed," Marques says.
Many cities lack weather station networks that can monitor heat islands comprehensively, so Marques and her colleagues took advantage of Internet-connected sensors that are increasingly becoming standard equipment in cars.
Such data could eventually fill gaps between fixed weather stations for applications that include mapping and monitoring urban heat islands.
Some small French cities that lack sophisticated weather station networks nonetheless want to use heat maps to assess urban conditions, Marques says.
Lower-income cities in tropical regions are historically understudied in urban climatology, and many still do not have access to the instruments that benefit other parts of the world-yet they are among the most vulnerable to urban heating.
More detailed maps of these cities could help planners design climate mitigation and adaptation strategies to address problematic spots within individual heat islands.