Roads and sidewalks in some areas are so hot that skin contact can cause second-degree burns. NASA uses the ECOSTRESS instrument to map surface temperatures in Phoenix, revealing burning risks and the cooling benefits of green space. This research highlights urban heat challenges and supports strategic urban planning.
Researchers at NASA's Jet Propulsion Laboratory (JPL) in Southern California have mapped hot pavements in Phoenix where contact with skin - such as a fall - can cause severe burns. The image shows the surface temperature of a road grid and adjacent sidewalks, revealing how urban spaces can become dangerous in hot weather.
The visualization of the Phoenix area, the fifth most populous city in the United States, was collected by an instrument aboard NASA's International Space Station on June 19, 2024, at 1:02 p.m. local time. The instrument, called ECOSTRESS (short for Space Station Ecosystem Airborne Thermal Radiometer Experiment), measures thermal infrared radiation from the Earth's surface.
The image shows how miles of asphalt and concrete surfaces (shown here in yellow, red and purple depending on temperature) absorb heat. These surfaces are at least 120 degrees Fahrenheit (49 degrees Celsius) to the touch, enough to cause contact burns in minutes to seconds.
The images also show the cooling effect of community green spaces such as Encanto and Camelback East, in contrast to higher surface temperatures in Maryvale and Central City, which have fewer parks and trees.
"The maps we created are very intuitive for users and help make data more accessible to the public and citizen scientists," said JPL climate researcher Glynn Hulley. "We believe these maps are an important tool for planning effective heat cooling measures, such as tree planting, to cool the hottest roads and pavements."
At the bottom right of the image is Phoenix Skyport International Airport, where ECOSTRESS recorded the city's hottest surface temperature - about 140 degrees Fahrenheit (60 degrees Celsius). On June 19, the temperature at the airport reached 106°F (43°C).
Air temperatures measured outside of direct sunlight can differ significantly from surface temperatures. Because dark-colored asphalt pavements absorb more sunlight than light-colored pavements, streets are often the hottest surfaces in the built environment; asphalt absorbs up to 95% of solar radiation. On hot days, these pavement surfaces can easily be 40 to 60°F (22 to 33°C) warmer than the air temperature.
Launched to the International Space Station in 2018, ECOSTRESS's main mission is to identify plants' water thresholds and water stress to gain insights into plants' ability to adapt to climate warming. However, the instrument also helps record other heat-related phenomena, such as endothermic and holding modes.
To create the image of Phoenix, the scientists used a machine learning algorithm that included data from other satellites: NASA/USGS Landsat and Sentinel-2. The combined measurements "sharpen" surface temperatures to a resolution of 100 feet (30 meters) by 100 feet (30 meters).
ECOSTRESS, or the Space Station Ecosystem Airborne Radiometer Experiment, is a NASA instrument installed on the International Space Station. It measures thermal infrared radiation emitted by the Earth's surface and is used to study water use and stress levels in plants, urban thermal phenomena, and other heat-related aspects. By providing high-resolution temperature maps, ECOSTRESS helps scientists understand how plants respond to heat and drought and assists urban planning by identifying hot spots in cities. This information is critical for managing water resources and mitigating the effects of urban heat islands.
Compiled from /ScitechDaily