G-LiHT | A View From Above

July 21st, 2014 by Kathryn Hansen

Text by Doug Morton
NASA’s Goddard Space Flight Center

G-LiHT DSLR image of forests and open water near the Tetlin National Wildlife Refuge east of Tok, Alaska. Credit: NASA

G-LiHT DSLR image of forests and open water near the Tetlin National Wildlife Refuge east of Tok, Alaska. Credit: NASA

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.

Spruce forest in the Yukon-Charley Rivers National Preserve north of Delta Junction, Alaska. Credit: Ross Nelson/NASA's Goddard Space Flight Center

Spruce forest in the Yukon-Charley Rivers National Preserve north of Delta Junction, Alaska. Credit: Ross Nelson/NASA’s Goddard Space Flight Center

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.

Rainbow over the Tanana River. Credit: Bruce Cook/NASA's Goddard Space Flight Center

Rainbow over the Tanana River. Credit: Bruce Cook/NASA’s Goddard Space Flight Center

 

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Notes from the Field