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UC IRVINE PRESS RELEASE - A new study funded by a NASA grant awarded to the University of California, Irvine’s Joe C. Wen School of Population & Public Health has found that public parks in underserved areas of Los Angeles can reach dangerously high temperatures, in some cases hot enough to cause pain or burns, because of the materials used to build them.
The differences stem largely from what parks are made of. Researchers discovered that parks in South Los Angeles contain significantly more heat-retaining materials – such as artificial turf, concrete and rubber – while parks in West Los Angeles are far more likely to feature natural turf and vegetation. The research, published recently in npj Urban Sustainability, a journal in the Nature Portfolio, analyzed park temperatures across Los Angeles County using satellite data from Ecostress, a thermal imaging experiment aboard the International Space Station. The results show stark temperature differences between parks in South Los Angeles and those in West Los Angeles, revealing how urban design and historical investment patterns shape exposure to extreme heat. The study, conducted with collaborators from Chapman University and Tennessee State University, found that parks and open spaces in South Los Angeles averaged 105.8 degrees Fahrenheit during summer daytime conditions, compared with about 91.6 degrees Fahrenheit in West Los Angeles. More than a third of parks and recreational spaces in South Los Angeles reached or exceeded the surface temperature associated with the human pain threshold. No parks in West Los Angeles reached that point. “Parks are often thought of as cooling refuges during extreme heat,” said Jason A. Douglas, associate professor and vice chair in Wen Public Health’s Department of Health, Society & Behavior. “But in some underserved communities, the parks that should provide relief are actually exposing residents to dangerous levels of heat.” Natural surfaces, such as those more featured in West Los Angeles parks, help cool the environment through shade and evapotranspiration, the process by which plants release moisture into the air. Artificial materials absorb and retain heat. The research also found stark differences in access to green space. Using a per capita measure to account for differences in study area size, West Los Angeles has 117.1 hectares of parkland per capita, compared to 9.1 in South Los Angeles. “Residents in South Los Angeles face a double burden,” said Joshua Fisher, an associate professor of environmental science at Chapman University’s Schmid College of Science and Technology. “They have less access to parks, and the parks that do exist are often built with materials that trap heat instead of cooling the environment.” The work used satellite observations collected between 2021 and 2024 to measure land surface temperatures at hundreds of parks and recreational areas, including schoolyards, playgrounds and open spaces. Employing machine-learning techniques, the team increased the resolution of the satellite data to analyze temperature differences across specific surfaces, such as grass, artificial turf and pavement. The project was shaped in part by community concerns. Residents working with the environmental justice organization Communities for a Better Environment reported extremely hot park surfaces during community workshops and heat pocket mapping sessions. Some said that artificial-turf fields and playgrounds were hot enough to burn bare feet during summer months. Those experiences prompted the research team to investigate whether the thermal conditions described could be measured across many parks using large-scale data, such as satellite observations. Extreme heat is the deadliest weather-related hazard in the United States, and urban heat islands – built infrastructure that absorbs and traps heat disproportionately – tend to affect lower-income communities and people of color. The study’s authors said the findings highlight how decades of unequal investment in urban infrastructure continue to shape environmental conditions and public health risks in cities. “Parks should be part of the solution to extreme heat,” Douglas said. “But the design and materials used in these spaces matter. If we want parks to protect communities during hotter summers, we need to invest in vegetation, shade and natural surfaces that actually cool the environment.” The study was led by Ashley Agatep, an undergraduate researcher at Chapman University. Besides Douglas and Fisher, co-authors include Kainani Tacazon of Chapman University, Reginald Archer of Tennessee State University, Ambar Rivera and Rossmery Zayas from Communities for a Better Environment, and graduate student Juan Carlos Ruiz Malagon of UC Irvine. This work was supported by NASA through its Equity and Environmental Justice Program and Ecostress Science and Applications Team. The researchers said their findings could help inform future urban planning and park development strategies aimed at reducing heat exposure in vulnerable communities. As climate change drives more frequent and intense heat waves across Southern California, they said, ensuring equitable access to effective cooling infrastructure will be critical for protecting public health.  Figure: The Park Fire started on the afternoon on July 24, 2024, just northeast of Chico, California. One week later, it grew to 391,200 acres. ECOSTRESS was able to capture the fire front on July 28, 2024, represented by bright yellow/red spots on the map, where temperatures exceeded 127 °C. ECOSTRESS also captured the smoke/ash plume expanding north-east with the prevailing winds, represented with cooler temperatures in gray color. Map produced by a high school student as part of the COSMOS program at UCLA. We are excited to announce the forthcoming release of a new book chapter co-authored with students from Observing Earth from Above. The chapter features five high school students who participated in a version of the course taught as part of a UCLA summer institute using the same curriculum as we use with our undergraduate students. Students produced outstanding data visualizations, including the one above. The book will be available on March 3, 2026:
Fisher, J.B., A. Gopalakrishnan*, J. Hegde*, J. van der Werf*, R. Shivakumar*, R.E. Fisher*, A. Agatep*, and G.R. Goldsmith. 2026. "Energy Drives Terrestrial Ecosystems: How it Works, Monitoring, and Tools for the Next Generation." In: High spatio-temporal-spectral thermal remote sensing: research and applications. Eds. Cawse-Nicholson, K., Luvall, J.C., and Lee, C. Routledge.  Jayden Morris, a student at Murray State University in Murray, Kentucky, produced this map of land surface temperatures in Nashville, Tennessee. Morris was interested in the urban heat island effect in one of the country's fastest growing cities. He writes in his analysis, now posted on the ECOSTRESS science website that "Visible as a dark streak across the image, the Cumberland River has the lowest temperature of any feature in the selected area due to water’s high specific heat capacity. Urban areas, which are covered by asphalt and other surfaces with low albedos, have temperatures up to 53 °C. In contrast, the surrounding forested neighborhoods are much cooler, with temperatures as low as 38 °C - this is up to 15 °C cooler than the treeless urban areas. Vegetation is effective in cooling urban areas.."
We're thrilled to have a new article describing Observing Earth from Above in the American Geophysical Union's news magazine EOS. In the meantime, we're happy to see the curriculum being used around the country, including in a course being taught this semester at Occidental College. 
What a privilege for 65 students from Chapman University, CSU Northridge, and University of California Riverside to take a tour of NASA's Jet Propulsion Laboratory in Pasadena. 
As students begin to make maps, we tend to see a lot of the same common mistakes. Here's a simple powerpoint presentation with some tips and tricks: Maps Are All About Details!  In this data visualization, the area with the data layer accounts for a very small proportion of the total area. Wherever possible, maximize the amount of area occupied by the data layer(s) of interest.
At this week's ECOSTRESS Science and Applications Team Meeting, the ECOSTRESS leadership offered an update on the available data, the differences between collection 1, 2 and the proposed collection 3 data, and the timeline for reprocessing. We reproduce this information below for the community, with the most up-to-date information available here: https://ecostress.jpl.nasa.gov/data  Here are the key differences in the collection 2 (currently forward processing and in the process of reprocessing) and the collection 3 (proposed only) versions of the data:  This may be the most useful information. Here, you can see how collection 2 is progressing, as well as what has already been reprocessed (as of October 3, 2024). Note that the plan is to completely remove access to collection 1 L1-L2 products once the collection 2 has been completely reprocessed; plan accordingly.   Ashley Agatep, an environmental policy and science student who participated in our course in fall 2023, has generated a visualization of ECOSTRESS data that is now featured among the "best science images" for the month of July by Nature Magazine. Agatep spent the summer at NASA's Jet Propulsion Laboratory in Pasadena, CA, where she created the image as part of her internship.
Agatep mapped scorching pavement in Phoenix where contact with skin - from a fall, for example - can cause serious burns. The image shows land surface temperatures across a grid of roads and adjacent sidewalks, revealing how urban spaces can turn hazardous during hot weather. You can read more in news coverage from Scientific American. |
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