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ASU prof maps campus to find the shadiest route.
Shade can make you feel up to 18 degrees cooler, ASU urban climatologist says.
May 30, 2017

Ariane Middel builds mobile weather station to map the most comfortable route through campus on a hot summer day

In an Arizona summer, the best parking spot is not the one by the door. It’s the one a quarter-mile away under a tree.

Ariane Middel, Arizona State University urban climatologist and hunter of shadows, knows this and has created a method to show us a cool way through the shade.

Middel, an assistant research professorMiddel is also a senior sustainability scientist in the Julie Ann Wrigley Global Institute of Sustainability and on the honors faculty at Barrett, The Honors College at Arizona State University. The School of Geographical Sciences and Urban Planning is an academic unit of the College of Liberal Arts and Sciences. in the School of Geographical Sciences and Urban Planning and a faculty affiliate of the Urban Climate Research Center, has developed a tool that will someday show pedestrians the shadiest — and hence coolest — route to their destinations. It also will tell planners and architects where they should throw shade.

She and a team of computer scientists used high-resolution Google Earth images to generate 180-degree “fish-eye” views to calculate whether a specific location would be in the sun or shade during a certain time of day. It’s a big-data approach that seizes upon Middel’s research.

Two years ago, she led a study to investigate thermal comfort at the university’s student union in Tempe. She and her team found that shade was the most important factor for comfort. Shade can make you feel up to 18 degrees cooler, while air temperature might only vary by 5 degrees. That got her interested in studying shade further.

“Keeping cool and staying comfortable is really difficult here in the desert in summer,” Middel said. “Out of all the variables that determine how comfortable you feel, shade is the most important factor, more important than air temperature, relative humidity, even the clothing that you’re wearing. Shade is the most important factor. That led me to look into the impact of shade on your thermal comfort when you’re outdoors.”

Video by Ken Fagan/ASU Now

The issue with shade is that it “travels” during the day, depending on the position of the sun. If you look at a north-south urban canyon, you will have shade from the building to the east in the morning, almost no shade at noon, and shade to the west in the afternoon. Middel wanted to look at the distribution of shade on campus and also assess the implications for thermal comfort.

To do it, Middel built a mobile weather station. (She calls it a mean radiant temperature cart. It looks somewhat like WALL-E.) Using the cart, Middel generated fish-eye views for the Tempe campus (one view every 5 yards) and then calculated thermal comfort for two times of day, 9 a.m. and 5 p.m., for a hot summer day last August.

“To make sure that the outputs from the model that we develop make sense, we have to ‘validate’ the outputs using real-world measurements,” she said. “I built a mobile platform that can measure thermal comfort (using three net radiometers that, simply put, measure the direct sunlight and the heat from surfaces that hit the human body from all sides).”

The next step was using the thermal comfort maps to find the most comfortable route from the Brickyard building on Mill Avenue to the Memorial Union. The algorithm suggested a more shaded route — longer than a direct route, but with much more shade.

“What we found measuring thermal comfort using the mean radiant temperature cart last summer was that thermal comfort varies a lot on campus,” Middel said. “It varies much more than air temperature.

“Mean radiant temperature, or thermal comfort, can be up to 60 degrees Celsius in the sun, but then it’s only 30 degrees Celsius in the shade. This is how you would feel this temperature as opposed to the air temperature you get from the weather report. There’s a huge variation due to trees, shade from buildings, shade from overhangs, different surface materials — all of this can be measured using this cart.”

Knowing the thermal comfort conditions at a very fine scale can be very helpful to architects and planners. It can be used in urban planning to assess whether an area has enough shade or maybe needs more shade.

University landscape architect Byron Sampson constantly hears pleas for more shade on campus. A tool like Middel is developing would be very useful to him, he said.

“If the interface will let the user know the shadiest route, we can learn where interventions need to take place and predict pedestrian movement through the university during different seasons,” Sampson said. “The paths do change and evolve over time.  As we look at the form of the built and open spaces in terms of development, we should be able to influence the architectural form to increase the shaded routes in areas where trees cannot be used to do the same.”

ASU urban climatologist Ariane Middel

This and top photo: ASU urban climatologist Ariane Middel uses her mean radiant temperature cart to measure thermal comfort of different spots on campus. Photos by Ken Fagan/ASU Now

 

As the Phoenix metro area becomes more urban and densities increase, shade will become the asset an area is judged by, Sampson said.

“If you look at the older neighborhoods with large trees (hint: more shade), the property values seem to be higher and stable,” he said. “This could also be a means to have interventions in poorer areas to increase the comfort level and significantly reduce the heat island in the Valley.”

Development on the tool continues. Middel has been using an existing thermal comfort model to translate the fish-eye information into thermal comfort. The model isn’t suited for large areas, because it only works for one fish-eye photo at a time.

“We are currently developing our own outdoor thermal comfort model,” she said. “Once working, (it) will be able to calculate thermal comfort at street level for any city where Google Street View data and basic weather station data are available.”

As Shakespeare said in “A Merchant of Venice,” “Some there be that shadows kiss; Such have but a shadow’s bliss.”

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Scott Seckel

Reporter , ASU Now

480-727-4502

 
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Decoded genome may help tortoise win race to survive

May 31, 2017

Slow and steady wins the race.

While that may have been true in one of Aesop’s classic fables, the Mojave Desert tortoise may need to adapt more quickly than it has in decades past. The species is facing serious threats to its survival, from invasive plants to man-made changes in the landscape.

But researchers from Arizona State University’s School of Life Sciences and their collaborators may have a new tool to help conserve this iconic desert reptile. For the first time, they have decoded the animal’s genome; their findings appear in the current issue of the journal PLOS ONE.

The breakthrough could help the animal survive an increasing number of threats.

Tortoise habitat

Mojave Desert tortoise habitat is negatively affected by power lines, development, highways and changes across the landscape. Photo by Sandra Leander/ASU

“There is more and more development across deserts, as well as a surge of renewable energy development,” said Todd Esque, a research ecologist and tortoise expert with the U.S. Geological Survey. “Highways and power lines disturb the tortoise habitat. We are also considering impacts to tortoise habitat from changes across the landscape. 

“And, in the last 100 years, we’ve had invasive grasses come in with livestock, probably mostly accidental. Red brome and Mediterranean grass are the two primary invasive grasses we have here. A diet of primarily red brome is really a bad diet for little tortoises and their survivorship is much lower.” While Esque was not involved in the project, the study’s findings may assist tortoise conservation efforts.

Government agencies and other researchers have been monitoring tortoise populations in the Southwest for more than two decades. The Mojave Desert tortoise population has seen considerable decline in its habitat that includes California, Nevada, Utah and Arizona. This species is listed as ‘threatened’ under the U.S. Endangered Species Act and is considered ‘vulnerable’ by the International Union for Conservation of Nature (IUCN). 

Marc Tollis, lead ASU investigator on the project, said the genome is an important resource for the conservation of the Gopherus agassizii tortoise, particularly because this population is suffering from a serious disease. Researchers don’t yet fully understand its cause or what makes tortoises susceptible to it.

“We don’t know how the tortoise is handling the fact that it’s also being threatened by an upper respiratory disease,” Tollis said. “Decoding this genome will help us catalog which tortoise genes are evolving quickly enough to help them overcome this threat.” 

woman monitoring desert

Kristina Drake, biologist with the U.S. Geological Survey, monitors desert tortoise populations in the Mojave Desert. Photo by Sandra Leander/ASU

 

Tollis, a postdoctoral researcher, along with the paper’s senior author Kenro Kusumi, obtained the genetic data for a particular tortoise specimen, assembled and annotated the genome and learned about the evolutionary history of tortoises.

“Decoding a genome has gotten technically a lot easier,” said Kusumi, senior investigator for the project and professor with the ASU School of Life SciencesThe School of Life Sciences is in the College of Liberal Arts and Sciences.. “What’s challenging now is decoding the information in the tortoise genome. We can use clues from similarities with the mouse and human genomes. Finding the proverbial ‘needle in the haystack’ would be to identify the genes that direct the immune response to infectious disease, as well as the ability to survive the harsh conditions of the Mojave Desert.” 

Kusumi added that it’s important for the research team to learn where tortoise diversity is located across its geographic range. Identifying hotspots of genetic diversity helps manage the species from a conservation standpoint and preserve tortoise populations that could respond better to unknown challenges in the years ahead.

Greer Dolby, co-author and ASU postdoctoral associate, is analyzing the genetic differences between this tortoise and its sister species, the Sonoran Desert tortoise.

Dolby said: “My hope is that this study will enable other agencies to ask new questions, questions they would not have been able to ask without this research. For instance, ‘What immune genes do tortoises have to fight pathogens? How does their immune system function in an environment with lots of threats? And, how might a changing environment impact this?’ These are important questions to answer in managing the species. Now, we can begin investigating.” 

Adapted for life in a harsh desert

Many tortoises living in the study site are fitted with small GPS units. This allows biologists to know where they are and how much they’ve traveled over a certain season. Scientists regularly check the tortoises for things such as overall health, body condition and signs of disease or stress. 

Beginning in mid-October through November, the tortoises hibernate, only coming out of their burrows to drink water when it rains. When the weather warms up in March, they become active again and will mate during the spring. Females will lay a clutch of eggs up to three times per year depending on the weather. 

Incredibly, desert tortoises can live up to 50 years in the wild, with lifespans estimated between 30 to 50 years. Tortoises in captivity have been known to live as long as 100 years.

Predators include ravens and coyotes, but other factors such as climate change, invasive grasses and human activity also negatively affect tortoise populations.

Using genome information in conservation

The future is uncertain for the desert tortoise, as it continues to face multiple threats. 

“In a best-case scenario, the work we do with ASU will help us understand how to inform the scientific methods designed to increase conservation and perpetuate the survival of this species,” Esque added. 

The genome provides a starting point for a number of studies focusing on disease resistance, adaptations to the desert environment, distribution of genetic diversity across its range and hybridization with its sister species.

Ultimately, insights from the decoded tortoise genome should help guide how this threatened species is managed and may improve its chances of long-term survival.

 

 

Arizona State University’s College of Liberal Arts and Sciences and the U.S. Marine Corps (Natural Resources and Environmental Affairs, Marine Corps Air Ground Combat Center/Marine Air Ground Task Force Training Command) funded the research project. Collaborators include the University of Arizona; U.S. Marine Corps; and Royal Ontario Museum.

Top photo: Red brome and Mediterranean grass are invasive grasses in the Mojave Desert. A diet of red brome is bad for little tortoises and their survivorship is low. Photo by Sandra Leander/ASU

Sandra Leander

Manager, Media Relations and Marketing , School of Life Sciences

480-965-9865