NASA's ECOSTRESS Shows Overnight Heat in London

NASA's Ecosystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) instrument recorded this image of ground surface temperatures in London and surrounding areas on July 15, 2022, just before midnight local time. It shows surface temperatures exceeding 68 degrees Fahrenheit (20 degrees Celsius) at 11:57 p.m. British Summer Time.

Parts of Europe in mid-July experienced a record-breaking heat wave. The United Kingdom reaching its highest air temperature on record on July 19, 104.5 F (40.3 C) in Coningsby, about 110 miles (177 kilometers) north of London, which itself saw a high of 104.3 F (40.2 C) the same day. That evening, the overnight low was also a record-breaker: 78.4 F (25.8 C) at Kenley Airfield in Greater London.

In this image, the red areas indicate hotter temperatures commonly associated with developed areas. These surfaces – roofs, paved streets, and other built structures – remain warm long after the sun sets. Blue and green areas indicate cooler areas commonly associated with parks and other natural land surfaces. Because this image was acquired at night, it shows bodies of water being warmer than the land surface. This is because water tends to change temperature more slowly, so its temperature stays elevated long after land surfaces have cooled down.

Cities are usually warmer than open land with natural surfaces because of human activities as well as the materials used in building and construction. Streets are often the hottest part of the built environment due to asphalt paving. Dark-colored surfaces absorb more heat from the Sun than lighter-colored ones; asphalt absorbs up to 95&percnt of solar radiation and retains the heat for hours into nighttime. This image overlays ECOSTRESS surface temperature data on a Google satellite map for context.

ECOSTRESS measures the temperature of the ground, which is hotter than the air temperature during the daytime. The instrument launched to the space station in 2018. Its primary mission is to identify plants' thresholds for water use and water stress, giving insight into their ability to adapt to a warming climate. However, ECOSTRESS is also useful for documenting other heat-related phenomena, like patterns of heat absorption and retention. Its high-resolution images, with a pixel size of about 225 feet (70 meters) by 125 feet (38 meters), are a powerful tool for understanding our environment.

NASA's Jet Propulsion Laboratory in Southern California built and manages the ECOSTRESS mission for the Earth Science Division in the Science Mission Directorate at NASA Headquarters in Washington. ECOSTRESS is an Earth Venture Instrument mission; the program is managed by NASA's Earth System Science Pathfinder program at NASA's Langley Research Center in Hampton, Virginia.

More information about ECOSTRESS is available here: https://ecostress.jpl.nasa.gov/.