The Alaska G-LiHT Campaign is a partnership between scientists and NASA and the U.S. Forest Service (USFS). The design for the research is to link field measurements of forest structure, vegetation composition, and soils with airborne remote sensing data from G-LiHT. At this stage of the mission, the flight planning looks a little like a technicolor version of Pac-Man. Pink lines on the flight GPS units intersect points showing the location of ground measurements. In flight, the goal is to gobble as many of these dots as possible. Sometimes you wonder if the familiar “wocka wocka” noise of the old video game can be heard above the noise of the engine.
NASA and USFS partners have also worked hard to connect G-LiHT flights to other research activities in the valley. Within NASA, overlapping G-LiHT and MABEL flights are planned to characterize ice cover high in the Alaska Range west of Denali and across the Nebesna Glacier in Wrangell-St. Elias. Overlapping coverage is also planned with two hyperspectral missions from USGS (PI Ray Kokaly) and the U.S. Army Corps of Engineers (PI Steve Newman), offering the chance to compare different hyperspectral imaging systems and share ground calibration data.
G-LiHT flights will also cover a range of existing forest inventory plots collected by collaborators at the Department of Defense lands (Dan Rees), National Park Service (Carl Roland, Colin Malone), and the Alaska Department of Natural Resources (Chris Maisch, Doug Hanson). A dense network of flight lines is planned in and around the Bonanza Creek Experimental Forest and the Caribou Poker Creek Research Watershed to cover research plots established by scientists at the University of Alaska Fairbanks (Jaime Hollingsworth, Glenn Juday, and David McGuire, among others).
Further afield, still more dots on the flight plan represent long-term studies of forest recovery from fire. More than 40 percent of the watershed has burned since 1950, and G-LiHT will sample about 80 percent of large wildfires that have burned over the past 60 years. Record rainfall this summer has kept fire activity in check, but G-LiHT data from 2014 will also provide a benchmark for assessing changes from fires in coming years. Each of these intersecting lines and points represents a new opportunity for collaboration with the Alaska G-LiHT Campaign in 2014.
Text by Doug Morton
NASA’s Goddard Space Flight Center
I have always enjoyed looking out the window of a plane. From the typical cruising altitude of a commercial jetliner, the view of lakes and fields and mountains is familiar (but still fascinating) to a NASA scientist used to looking at Earth from space. Vegetation and land use follow the topography in predictable ways — agricultural fields on the flattest lands and dense forest cover on the warm, south-facing slopes.
In Alaska, the G-LiHT campaign is flying low and slow to provide a very detailed look at forest structure, topography, wetlands, and forest health. At 1,100 feet above ground level, the view from above is stunning. Looking down, you see individual trees, small polygons formed by permafrost, and subtle changes in topography that allow vegetation to flourish on dry ground or wallow in the wetlands of the Tanana flats. Small black spruce trees, barely head high and the width of a dinner plate, are packed together in stands too thick to walk through. Looking out, you can see the vast expanse of the Tanana Valley, a lush green carpet of forest. The braided channels of the river flash in the sunlight as the milky white water heads out of the mountains. Ahead, the steep rise of the Alaska Range signals the end of another flight line.
Seeing the landscape from the same perspective as the G-LiHT sensors provides essential context for the project. The G-LiHT operators on the plane can switch between the real-time view of the incoming data stream and the landscape below. G-LiHT PI Bruce Cook noted, “it’s a little dizzying to watch the imagery fly by on the screen, but matching the bird’s eye view to the data gives an idea of what is possible with the analysis and interpretation of the G-LiHT data.”
Update: As of July 19, the piper had flown more than 70 hours for data collection (9,300 miles), and with more than half of the planned flight lines in the Tanana region completed.
Text and photos provided by Doug Morton
NASA’s Goddard Space Flight Center
NASA and USDA Forest Service scientists are collaborating on an ambitious project to inventory forest resources in the Tanana Valley of interior Alaska, a region the size of Iowa. The pilot project, funded by the USDA Forest Service Pacific Northwest (PNW) Research Station and NASA’s Carbon Monitoring System (CMS), combines forest inventory plots and airborne remote sensing data from NASA Goddard’s Lidar, Hyperspectral, and Thermal Airborne Imager (G-LiHT). The remote forests of interior Alaska have never been included in national inventories of U.S. forest resources based on the costs and complexity of acquiring field data in remote and difficult terrain.
The partnership between NASA and the Forest Service leverages unique capabilities for airborne remote sensing and ground surveys of forest structure and composition. For NASA, key research questions include the spatial distribution of forest carbon stocks, disturbance and recovery from fire, and data fusion—including the opportunity to characterize forest composition using a combination of lidar, hyperspectral, and thermal data from G-LiHT. G-LiHT data collections will also benchmark conditions across the Tanana Valley, an important part of the research domain for NASA’s Arctic and Boreal Vulnerability Experiment (ABoVE). For the Forest Service, the project will test the tradeoffs between a traditional ground-based surveys of forest resources and a hybrid approach to combine a limited ground sample with extensive coverage using G-LiHT airborne lidar and image data. Both NASA and the Forest Service are interested to track changes in forest cover and composition from wildfires and warming climate in coming decades.
As of July 14, the G-LiHT team had completed 40 percent of the planned flight lines across the Tanana region, totaling 3 TB of raw data and more than 2 billion laser shots fired. The flight crew is currently based out of Tok and Fairbanks, Alaska.