Even though they deal mostly with water, scientists at the Global Hydrology and Climate Center (GHCC) are looking forward to getting data from a satellite designed to study land.
"Landsat 7 is going to help us out tremendously in urban heat island studies," said Dale Quattrochi, a NASA scientist at the GHCC in Huntsville, Alabama. Quattrochi and Jeff Luvall are the GHCC's lead scientists studying urban heat island phenomenon. The central effort has been the long-term Project ATLANTA (ATlanta Land-use ANalysis: Temperature and Air-quality) which includes a University of Georgia team led by Dr. C.P. Lo. The results of Project Atlanta led to 1998's Urban Heat Island Pilot Project (UHIPP) which conducted similar measurements over Baton Rouge, Sacramento, and Salt Lake City.
At the core of the urban heat island effect is the fact that the evaporation of water absorbs a large quantity of heat. Plants, and trees in particular, evaporate large amounts of water from their leaves. 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 manmade materials are very effective at absorbing light and reradiating it as infrared radiation that raises the temperature of the air. In turn, that makes air-conditioning systems work harder, even after sunset.
Luvall, Quattrochi, and the Project ATLANTA team - especially Lo, who produced the Landsat maps of land use change and heat island change through time - have used these satellite data as an integral part of our project to relate land use changes with aircraft data collected over Atlanta in 1997.
"Landsat 7's 15-meter-resolution black-and-white images will be very useful in combining with digital data to give us a better idea of what happens on the ground," Quattrochi said.
The thermal infrared channel on Landsat 7's Enhanced Thematic Mapper will see details as small as 60 meters (188 feet) on the ground as compared to 120 meters (376 feet) with prior Landsats' thermal channels.
"It's a great improvement," Luvall said. "It will give us a temporal distribution across the years and the seasons" to show trends in urban heating. The scientists still need to use aircraft, as in 1998's UHIPP, for detailed images to pinpoint individual heat sources. Aircraft are also needed to provide images to show heat storage the night immediately after a daytime observation since Landsat's orbit does not provide that sort of coverage.
Landsat 7 will also help scientists look into the past so we can chart the future better.
"Landsat 7 will be used with other remote sensing techniques to address issues in Mayan archeology and to monitor the effects of increasing deforestation in the area," said NASA archaeologist Tom Sever.The Peten, northern Guatemala, was inhabited by a population of several million Maya before their collapse in the 9th century A.D. The seventh and eight centuries were a time of crowning glory for millions of Maya; by 930 A.D. only a few scattered houses remained, testifying to one of the greatest disasters in human history. What is known is that at the time of their collapse the Maya had cut down most of their trees.
After centuries of regeneration the Peten now represent the largest remaining tropical forest in Central America but is experiencing rapid deforestation in the wake of an invasion of settlers. The successful adaptive techniques of the indigenous population are being abandoned in favor of the destructive techniques of monoculture - raising a single crop - and cattle raising.
"Already, images from earlier Landsats have helped us track the loss of rain forests to farmers and loggers," Sever said. "It has also helped us recover several archaeological sites. Landsat 7's enhanced capabilities will be of great benefit to our efforts to answer questions about the past in order to protect the resources of the future."
Dr. Dale Quattrochi, one of the lead scientists on the urban heat island study, was recognized as a world leader in the field of thermal infrared remote sensing by the Association of American Geographers' Remote Sensing Specialty Group. Quattrochi received the group's Outstanding Contributions Medal for 1999 at the group's annual convention in Hawaii. The Outstanding Contributions Medal is the only award presented in the remote sensing field by the AAG. Quattrochi is one of only two NASA or non-academic researchers to receive the award since its inception in 1980. Quattrochi earned a doctorate in geography from the University of Utah in Salt Lake City, a master's degree from the University of Tennessee in Knoxville and a bachelor's degree from Ohio University in Athens.