Technology Transfer

Promising New Thermal Study Spinoffs

ENVIRONMENTAL PLANNING FOR THE 2002 Olympic Games, strategies to reduce ozone levels, focused tree-planting programs for cooling cities and the identification of materials for cooler building roofs are early spinoffs from a NASA urban study just concluded in three U.S. cities. These new efforts of the Urban Heat Island Pilot Project (UHIPP) also could mean decreased health problems from heat stress and lower utility bills from less overworked air conditioners, even after sunset.

Ground teams with airborne and satellite sensors and cameras observed three "pilot" cities: Baton Rouge, Louisiana, on May 18; Sacramento, California, on June 29; and Salt Lake City, Utah, July 13 and September 15 (a second flight because of instrument problems on the first). Several other U.S. cities participated through ground-based and satellite observations. Atlanta was studied in May 1997.

A thermal camera took each city's temperature and produced an image that pinpoints each city's "hot spots." The images are being used to study which city surfaces contribute to bubble-like accumulations of hot air, called "urban heat islands."

"This is not a research project," said the study's lead investigator, Dr. Jeff Luvall of Marshall Space Flight Center's Global Hydrology and Climate Center. "We want to get the data out to city planners as soon as possible."

Salt Lake City is using the early results to help plan sites for the 2002 Olympic Games and develop strategies to reduce ground-level ozone concentrations in the Salt Lake City valley. While at high altitudes ozone protects Earth from ultraviolet rays, at ground level it is a powerful and dangerous respiratory irritant found in cities during the summer's hottest months. In Sacramento and Baton Rouge, city planners and tree-planting organizations are using the study to focus their tree-planting programs.

"We are helping the cities incorporate the study into their urban planning," said Maury Estes, an urban planner on Marshall's science team. "By choosing strategic areas in which to plant trees and by encouraging the use of light-colored, reflective building material, we think that the cities can be cooled."

The evaporation of water absorbs a lot of heat. Plants—and trees in particular—evaporate large amounts of water from their leaves. The energy required to evaporate water is taken from the air and from the sunlight intercepted by the leaves, thus cooling the air. Trees are also very effective in shading the ground, thus preventing the heating of the surface by sunlight.

On the other hand, asphalt, concrete and other artificial materials are very effective at absorbing light and re-radiating it as infrared radiation that raises the air's temperature. The science team will continue to analyze the thermal heat information. Luvall and his colleagues and scientists at Lawrence Berkeley National Laboratory are producing computer models so city planners nationwide can better predict the heat island effect for their cities, and then plan remedies.

"The sooner we can get the data out to the people, the quicker they can learn how to deal with it when the calibrated sets are available," Luvall said. "We're starting to develop sample data sets, even though they're not fully calibrated, to get the feel for how to handle it."

The data packages will include public domain software and low-cost geographic information systems to help city planners map the data onto specific parts of their cities. The computer information will swell when the data are fully calibrated to correct for atmospheric interference and apply laboratory optical bench calibrations to the instruments.

NASA's Earth Science Enterprise supports this study. Another purpose of this project is to focus on the Enterprise's efforts to make more near-term economic and societal benefits of Earth science research and data products available to the broader community of public and private users. Also working on the study with Marshall researchers, Lawrence Berkeley and the organizations from the three cities are the U.S. Environmental Protection Agency and the U.S. Department of Energy.

For more information, contact Dr. Jeff Luvall or Tim Tyson at the Global Hydrology and Climate Center, Marshall Space Flight Center. Call: 256/922-5886, E-mail: jeff.luvall@msfc.nasa.gov
Or Tim.Tyson@msfc.nasa.gov
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A NASA Lear 23 jet carried a film camera that provided visible images of hot and cold spots matching known ground objects.

Thermal images such as this one of downtown Baton Rouge are helping city planners plan remedies to the heat island effect in their cities.