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David Knapp poses before a sublime landscape of lush
mountains, his backyard for over two years while working for
NASA in Brazil.
August 26, 2005
A series of parallel ridgelines and interspersed valleys cut horizontally across an otherwise unexceptional landscape of patchy farmland and meandering highways. You can run your hand across the tops of the mountains, trace the length of the valleys with your fingertips, or press your nose against the contours of the flatlands for a closer look. The ridges jut out from a three-dimensional relief map of central Pennsylvania tiled across the wall on the third floor of Walker Building. To graduates of the Department of Geography at Penn State, the map is almost iconic - a steadfast symbol of a department that has shaped the progress of the field of geography as much as it has been shaped by it. David Knapp did more than a double-take upon first encountering the map when he was an undergraduate at Penn State; he walked two doors down to the office of the geography undergraduate advisor and never looked back.
Finding the Path
David grew up in Middlesex County, New Jersey. He began studying aerospace engineering at Penn State University in 1982, but one year in, dissatisfied with his major, a friend in geography happened to show David a map project he was completing. The blend of technical and creative skills required to create the map enticed David, and he promptly made an appointment to see Frederick Wernstedt, then undergraduate advisor for the Department of Geography. Impressed by topo map-lined corridors, career prospects in the nascent field of GIS, as well as the amount of time and genuine concern for his academic path afforded him by Dr. Wernstedt, David joined the department.
"Those were the early day of GIS," David recalls. "The lessons I learned in Peter Gould's spatial analysis class during my time as an undergraduate in the Geography Department are still applicable today, though; the research support I do now draws greatly from the fundamentals I learned from my training at Penn State."
After graduating from Penn State in 1987 with a B.S. in geography specializing in remote sensing and GIS, David worked for a short time for a land surveyor in Staten Island, New York. He entered the Department of Geography at the University of Illinois in the fall of 1988 as a master's student, again focusing on remote sensing. During his tenure at Illinois, David received a research assistantship at the U. S. Army Corps of Engineers' Construction Engineering Research Laboratory (CERL) in Champaign, Illinois, where the Geographic Resources Analysis Support System (GRASS) was developed. GRASS is a GIS used for geospatial data management, analysis, image processing, and spatial modeling.
"My colleagues and I at CERL developed GIS databases for various Army installations where land management was required," David says. "My prior GIS training was extremely valuable during my assistantship; we used relational databases to infer new spatial data layers from existing GIS data."
Concurrent with his work at CERL, David was carrying out thesis research, an endeavor that led him nearly three hundred feet below sea level to Death Valley, California. There he studied the effects of albedo in the valley's extremely arid environment by comparing in situ spectrometer measurements of reflectance and Landsat-derived surface reflectance.
"Through my thesis work in Death Valley, I learned a lot about the complex interactions between light, atmosphere, land surface, and sensor," David says. "Although the research on those topics has advanced a lot, the basic knowledge to understand these interactions are still the same."
NASA
David moved to the Washington, DC area after receiving his M.S. in geography from the University of Illinois in 1991. Initially enticed by the commercial applications of remote sensing, he found work with a commercial remote sensing company creating image products for earth resource and environmental interests. In 1993, however, he began working at the NASA Goddard Space Flight Center to study the effects of land use change on climate using satellite and aircraft imagery. The following decade with NASA would lead him more and more down the path of research applications for remote sensing - an aspect of his work that David has continually grown to appreciate.
David's first project with NASA was the Boreal Ecosystem-Atmosphere Study (BOREAS), a large-scale experiment initiated in 1990 to investigate interactions between the boreal forest biome and the atmosphere using surface, airborne, and satellite-based observations.
After nearly six years with the BOREAS project, the Portuguese lessons David had been assiduously attending for the past six months paid off - his excellent language skills and dependable character earned him the opportunity to relocate his office - to Brazil!
Amazon forest canopy as seen from a viewing tower above
the treetops.
A Few Miles South
In 2000, David began work as Brazil Liaison Officer with a NASA-funded component of the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA), a continental-scale project, led by the Brazilian Ministry of Science and Technology, to study how changes in land use and climate affect the biological, physical, and chemical functioning of the Amazonia ecosystem. David worked in Brazil in two separate intervals over the next four years, first with the National Institute for Space Research (Instituto Nacional de Pesquisas Espaciais - INPE) and then with the National Institute for Amazon Research (Instituto Nacional de Pesquisas da Amazonia - INPA).
"My time in Brazil was a great experience. Because I was a guest from the United States, part of my job in Brazil was to be a liaison, maintaining positive relations with the Brazilian government on behalf of NASA," says David. "This involved assisting U.S. and Brazilian researchers with importing and exporting equipment and samples, as well as providing some translation support."
"I was able to learn a great deal about Brazilian culture as well. I lived in a small town called Cachoeira Paulista during the first two and a half years. There was very little English spoken in the town so I had no choice but to integrate quickly into their culture. In 2003, I moved to Manaus to work at INPA. Manaus is a much larger city in the heart of the Amazon region, and so it provided a different experience from the one in Cachoeira Paulista."
David met numerous scientists, both Brazilian and American, during his time in Brazil. Dr. Greg Asner, who David met in 1998, proved to be one of the most memorable of those acquaintances. Dr. Asner is a faculty member in the Department of Global Ecology at Stanford University, one of six research departments of the Carnegie Institution, a privately endowed organization with the aim of scientific discovery across diverse disciplines. Recognizing David's unique background in remote sensing, GIS, and his knowledge of Brazil, Dr. Asner recruited David to work for him in California.
Practical Applications
In May 2004, David returned to the U.S. and began working under Dr. Asner at the Carnegie Institution. He is currently working on two research projects there: 1) mapping the effects of deforestation and logging activity in Brazil; and 2) detecting invasive plant species in Hawaii.
Both projects involve remote sensing of the Earth's surface. Landsat-7, a U.S. satellite used to acquire remotely sensed images of the Earth's land surface and coastal regions, employs seven multi-spectral bands to discern land features. The different bands are sensitive to different wavelengths of light such as those from the visible, near-infrared, and shortwave infrared spectra. In this way, distinct characteristics of a landscape such as fraction of vegetation cover may be isolated and analyzed. David's work at the Carnegie Institution also involves the use of hyperspectral imagery, a relatively new technology that employs approximately 200 spectral bands, allowing for images with much higher spectral resolution and enhancing the differences in the landscape of a remotely sensed image based on variations between the many spectral bands. This budding technology holds the promise of distinguishing between plant species or ascertaining the concentration of certain chemicals in vegetation, all from an aircraft or satellite.
"My job requires that I view the world on a global scale. The Global Ecology Department conducts research that encompasses the entire Earth," says David. "This particular perspective is useful to ecologists who analyze trends in human-environment interactions across the whole planet."
Though content with his work in northern California, David still has the opportunity to travel to Brazil with his position at the Carnegie Institution. He plans to return to Brazil before the end of the year. David says he will continue focusing on the technical aspect of his field, applying different techniques to create data products that are useful to ecologists and other earth scientists.