Phoenix Rising: Urban Heat Island in Maricopa County

Category: Responding to Human Health Risks
Project Team: Arizona Health & Air Quality
Team Location: NASA Langley Research Center – Hampton, Virginia

Display of Land Surface Temperature (LST) profile for Maricopa County, Arizona, from MODIS Aqua satellite. Image Credit: Arizona Health and Air Quality II Team

Display of Land Surface Temperature (LST) profile for Maricopa County, Arizona, from MODIS Aqua satellite. Image Credit: Arizona Health and Air Quality II Team

Daniel Finnell
Teresa Fenn
Richard Muench
Ashley Brodie
Derrick Hunter

Kate Goodin (Maricopa County Department of Public Health)
Dr. Kenton Ross (NASA Langley Research Center)
Dr. Dave Hondula (Arizona State University)
Lance Watkins (Arizona State University)

Past/Other Contributors:
Emily Adams (Center Lead)
Amy Stuyvesant
Geordi Alm
Rocky Garcia
Emma Baghel
April Rascon
Bernardo Garcia


Extreme heat causes and exacerbates a number of health problems, leading to hospitalization and death in some cases. The problem of severe heat is notably felt in Maricopa County, Arizona, where the socially disadvantaged and physically vulnerable are especially susceptible to the effects of extreme heat. Within the Maricopa County limits is the city of Phoenix, a dense urban area surrounded by 300-2,000 m ridge lines above the valley floor. The volume of impervious surfaces, lack of shade and vegetation, and the high ridge lines surrounding the city exacerbate the heat stress by a phenomenon known as the urban heat island effect (UHI). After the sun sets, heat retained by impervious building materials is released at a decreased rate compared to natural vegetation and soil coverage. Ambient air temperatures in urban areas tend to be higher than the surrounding rural areas. Several organizations, including the Arizona Department of Health Services and the Phoenix Heat Relief Network, are working to create more effectively placed cooling centers and heat warning systems to aid those with the highest risk of exposure. This project created a Python tool using Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature parameters to generate heat maps that reference demographics data on extreme heat days. In addition to this, using the resources available at the Atmospheric Science Data Center (ASDC) will allow for access to near real-time data acquisition, which will aid the partners in providing spatially distributed relief during extreme heat events.

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gclub 27-05-2016, 21:44

Of course, Nathan! One of Ferrari Color’s facilities is in Salt Lake City, UT, so we definitely understand the harsh impacts of the desert sun. Best of luck keeping the new vehicle wrap looking fantastic!

tbsbet 25-05-2016, 05:05

Is there anyone who hasn’t admired the lovely beacon of Venus hanging bright in a cerulean sky? (So bright in fact, it is regularly reported as a UFO, or even more ludicrously, a mystery planet denied by orthodox astronomers).

Alec Courtright 15-04-2016, 11:21

Great Project! Any updated news on how your end-users are using the product more specifically?

Teresa Fenn 18-04-2016, 17:10

When last we spoke, they seemed interested in using it if there was a need to create maps of past heat waves, or if one of their studies needs land surface temperature data for a specific time period. There was also interest in expanding the tool to surrounding counties in Arizona, which can be done very easily.

Daryl Ann Winstead (Lake Victoria Water Resources II) 13-04-2016, 21:29

Great project! What was the resolution of the vulnerability map? Thanks!

Teresa Fenn 18-04-2016, 17:07

The map uses land surface temperature data, so the resolution is 1 km; however, the data was averaged to give one value for each census tract, so the resolution of the final map depends on the size of the census tract.

Jessica Sutton 13-04-2016, 13:47

Hi Teresa! Interesting project. Did you all think about doing a comparison between the hot spots of LST to the hot spots of AT? It would depend on the amount of in-situ data you had access to, but it could be interesting. I would have loved to see more of your maps and analysis in the video. Good job 🙂

Teresa Fenn 18-04-2016, 17:08

Interesting idea. The weather stations in the region are grouped in the urban area, so it may be possible. Maybe that can be someone else’s project.

Teresa Fenn 13-04-2016, 10:11

Because the maps were created using MODIS data, they are maps of land surface temperature. The Phoenix weather stations measure air temperature. The team did not have the time to convert land surface temperature to air temperature, so we were unable to use weather station measurements to validate our vulnerability maps.
This was kind of a long answer, but the short version is that, unfortunately, we were unable to perform a quantitative accuracy assessment.

Leigh Sinclair 12-04-2016, 12:12

Awesome! What’s the accuracy of the vulnerability map?


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