Flight Lines for Greenland Experiment

News

By Uyanga Bazaa
Winter 2008

Audrey Fusco, KU graduate student, and RaeLynn Butler, senior at Haskell Indian Nations University, worked on a variety of projects mapping the Jakobshavn Isbrae outlet glacier during the last academic year. The first project was to map the coastal area around Jakobshavn in preparation for the UAV test flight that the students finished last summer.

For this project, Fusco and Butler used an aeronautical chart to find and list peak elevation points along with the latitude and longitude coordinates for each point. Then they created an Excel spreadsheet that listed the elevation values and coordinates for each point. “We added these to a land satellite image of Jakobshavn, which already had elevation values, to increase the accuracy over rocky coastal areas,” said Fusco. The radar performance improves closer to the ground, but due to safety reasons the UAV cannot fly too low. The UAV will be flown 500 feet above the ice sheet during the test flight. Accurate information about the location of high points of elevation allows the pilots to fly without danger of crashing. The map will be used for the test flight in Greenland next summer.

The second project led by Fusco was to plan the aerial surveys that the CReSIS team flew this past summer. David Braaten, KU Geography professor and CReSIS Deputy Director said, “It is important for CReSIS to measure the change of the glacier to understand its impact on the rest of the world.” Fusco added, “Initially, David gave me a set of coordinates to use to create the grid, and told me how long the grid needed to be. Braaten and other scientists at CReSIS choose the most important area for data collection and plan the size of the grid according to our interests, keeping in mind resource limitations.”

Fusco planned two survey grids for the field season; one large grid, and one smaller grid which provides data at higher resolution. The smaller grid was 50 x 50km (31 x 31 miles) with grid interval spacing of 5 km (3 miles). The larger grid was 320 x 120 km (198 x 75 miles) with a spacing interval of 10 km (6 miles). After building the initial grids, the planning team realized that the small grid could be shifted by just a little and, because of the dimensions of the grid, fit right into the larger grid. This shortened total flight times because some gridlines overlapped. The next step in planning field missions is to plan individual flight missions. The flight paths are constrained by fuel limitations; the fuel capacity of the plane allows flights of about 1,150 kilometers (715 miles). First, Fusco laid out an initial plan for flight paths that would cover both grids, and then she worked with Dr. Braaten and Dr. Gogineni to optimize the paths. “I measured the distance covered in each mission and used this total distance and average speed of the plane (230 km/ hr). This gave us an estimate of the flight hours that would be used for the plans,”explained Fusco. The team found that they had resources available to cover more ground, and added four gridlines to the north side of the grid. The final optimization resulted in 38 flight paths. Each flight travelled over Jakobshavn channel between the airfield and the grid. This permitted extensive data collection over the channel without adding additional flight time.

For the 2008 field season, 20 missions (roundtrip flights over the grid) were mapped by Fusco and GIS instructor RJ Rowley, Haskell Indian Nations University. The area that Fusco mapped is around 20 thousand square miles (51,200 square kilometers) and covers around three percent of Greenland’s ice sheet. “In the aerial surveys, GIS mapping is particularly useful because it allows us to obtain geographic coordinates over the exact path that we want to cover,” said Fusco.