Story Credits: Article and design by
Julia Twichell at American Forests. Shade modeling and data analysis by
Dr. Isaac Buo. Collaboration, review, and analysis by
Lana Zimmerman and
Dr. V. Kelly Turner at UCLA Luskin Center. Computational support by
ASU SHaDE Lab. Collaboration and review by Sarah Peterson at Detroit Future City, and Dan Rieden at City of Detroit. construction by
Geri Rosenberg at American Forests. This project was made possible by funding from the Robert Wood Johnson Foundation.
For more information about UCLA Luskin Center's shade data, please contact Dr. V. Kelly Turner, Associate Professor of Urban Planning and Geography, at
vkturner@ucla.edu.
Photo credits (in order):
wiredforlego/ Flickr;
Brook Ward/ Flckr;
wiredforlego/ Flickr;
Sharon Mollerus/ Flickr; Joel Clark / American Forests; Joel Clark / American Forests; Google Street View of 3361 Gratiot Ave, Detroit MI (Nov 2023); Google Street View of 9157 Gratiot Ave, Detroit MI (Nov 2023);
kubia/ Flickr; Bulleit Bourbon/ American Forests; Joel Clark / American Forests;
Terence Faircloth/ Flickr.
1 Shindell, D., Zhang, Y., Scott, M., Ru, M., Stark, K., Ebi, K.L. (2020). The Effects of Heat Exposure on Human Mortality Throughout the United States. Geohealth, 4(4). DOI:
https://doi.org/10.1029/2019GH000234.
2 University of Wisconsin-Madison Nelson Institute Center for Climatic Research. (Last accessed, January 27, 2025). “Great Lakes Regional Climate Change Maps” GLISA,
https://glisa.umich.edu/great-lakes-regional-climate-change-maps/.
3 Stone Jr, B., Gronlund, C. J., Mallen, E., Hondula, D., O'Neill, M. S., Rajput, M., ... & Georgescu, M. (2023). How blackouts during heat waves amplify mortality and morbidity risk. Environmental Science & Technology, 57(22), 8245-8255.
4 Turner, V. K. et al. (2023). “The problem with hot schoolyards.” UCLA Luskin Center for Innovation,
https://innovation.luskin.ucla.edu/publication/the-problem-with-hot-schools/.
5 Lagune-Reutler, M., Guthrie, A., Fan, Y., & Levinson, D. M. (2016). Transit Riders' Perception of Waiting Time and Stops' Surrounding Environments. Transportation Research Board, retrieved from the University Digital Conservancy,
http://dx.doi.org/10.3141/2543-09.
6 Vibrant Cities Lab. “Trees calm traffic, reduce stress and car accidents, encourage walking and extend the life of pavement.” US Forest Service and American Forests,
https://vibrantcitieslab.com/research/transportation/#:~:text=Mobility%20Impact,-Traffic%20Calming&text=Trees%20can%20calm%20traffic%20and,within%20an%208%2Dyear%20period.
Methods: One-meter resolution shade was modeled at noon (minimum shade), 3 p.m. (hottest time of day), and 6 p.m. (maximum shade) using high-resolution 2022 USGS LIDAR point cloud data and Microsoft Building Footprints on June 21, the longest day of the year.
Four surface models were created using LIDAR: (1) all features above ground (FDSM), (2) ground elevations, (3) a Building Surface Model and (4) a Canopy Model. A Building Surface Model was generated by extracting pixels in the FDSM within Microsoft Building Footprints. The Canopy Model extracted all other pixels in the FDSM, and defined trees and other non-building shade features as pixels with heights greater than 1.3 meters. All other above-ground elevations were set to 0 because they are not high enough to provide shade for the average person standing outdoors (Buo et al., 2023). The Canopy Model predominantly reflects tree shade; however, it also contains other non-building features such as shade sails that are treated like trees.
The shadowing function of the SOlar LongWave Environmental Irradiance Geometry (SOLWEIG) model proposed by Lindberg et al. (2008) simulated the shade distribution from surface models at 1-m resolution. Total shade is a function of the transmissivity of foliated vegetation for shortwave radiation and shadows from buildings and tree canopy (Lindberg & Grimmond, 2011).
Unlike shade generated from the Building Surface Model, shadows from the Canopy Model can occur underneath an elevated feature (such as under tree canopy, a bridge, or a shade sail). The result are binary rasters that indicate the presence or absence of shade, including building shade, tree and other shade and total shade rasters. These rasters can be analyzed to calculate percent shade cover for any polygon using zonal statistics.
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