Operation IceBridge Moves North

News

By Katie Oberthaler
Summer 2010

Reid Crowe’s jaw wasn’t the only thing to drop upon seeing the thousands of miles of ice. The CReSIS graduate student said setting foot on Greenland for the first time this spring “was kind of like stepping onto the moon.” Flying over it, however, tested his stomach and stamina.

Crowe recounts one flight during this year’s airborne radar survey when the plane hit an air pocket. “We must have dropped straight out of the sky 500 feet. Stuff was flying in the air. Yet, someone was still calling out waypoints,” he said. “The whole day was just up and down and it was kind of like a rollercoaster, which is fun for a while. This was a roller coaster that lasted six or seven hours.”

Flying down thin mountain passages, pitch-rolling in large aircraft to calibrate machines, and being locked in a hotel during a “Code Delta” storm might cause anyone’s blood to run cold. For CReSIS scientists, these events added flavor to the over 200 hours spent zooming above Greenland aboard DC-8 and P-3 aircraft. This spring, CReSIS scientists continued their participation in NASA’s Operation IceBridge project. KU faculty Fernando Rodriguez-Morales and Carl Leuschen and KU graduate students Ben Panzer, Cameron Lewis, Reid Crowe, and Kyle Byers joined over 70 scientists for the largest aerial survey of the Arctic regions to date.

The three-month trip, which ran from March to May 2010, used a compilation of airborne instruments to provide repeated measurements of glacial surfaces and bedrock topography, snow thickness, and Arctic sea ice extent. CReSIS has collaborated with NASA throughout the past several years to study these components, most recently during the Antarctic IceBridge survey in 2009. In Greenland, CReSIS operated Ku-band and Snow Radars to collect sea ice data. The Multi-Channel Coherent Radar Depth Sounder (MCoRDS) was used over land-based ice on the DC-8 in March and April. CReSIS flew these systems in addition to a snow accumulation radar on the smaller, more agile P-3 aircraft over Greenland in April and May.

For this trip, the MCoRDS operated with five bowtie antennas on the DC-8 at 10 MHz bandwith. On the P-3, the MCoRDS system ran with fifteen bowtie antennas. To account for the increased array, CReSIS also operated an antenna switching system on the P-3 to alternate between receiving signals from antennas on the inside and antennas on the outside of the aircraft’s wings. The team also traded the Vivaldi antennas previously used for the snow accumulation radar for flat elliptical dipole antennas.

The DC-8’s flight lines focused on high-altitude coverage of sea ice areas. Based out of Thule Air Force Base, they surveyed both thick, multi-year ice near northern coastal regions and yearly Arctic Ocean masses as far away as Alaska and Norway.

Sea ice

Photo 1: Sea ice as seen from the windows of the DC-8. Photo Credit: Reid Crowe.

“When we monitor the sea ice, what we’re really looking for is how that is changing. What we’re monitoring is the thickness of the sea ice,” said Lora Koenig, NASA project scientist for the project. “We’re able to see where sea-level is and the ice’s freeboard. About seven-eights of the ice is floating below the water. When we’re able to see the height of the sea ice above the sea, we can estimate how much below the surface is ice.”

The survey deployed at the cusp of spring. This year, the sea ice reached its maximum extent on March 31 at 5.89 million square miles. The overall coverage exceeded those of recent years, but represented a below-average expanse compared with long-term satellite data record. Recent thinning of the older, thicker multi-year ice across the Arctic provides an alarming trend in warming oceans, The National Snow and Ice Data Center recently reported.

Ben Panzer, who operated the snow radar aboard the DC-8 and flew on the P-3 last year, said he did notice a difference in ice coverage. “I saw a whole lot more open water than last year. This is ice that doesn’t last from year to year.”

In addition to following ICESat orbit paths, the survey undertook four unique flights at different altitudes across the Northeast Ice Stream and the Zachariae Isstrøm using a ten kilometer grid. These areas comprise a major outlet for the Northern Greenland ice sheets. “It’s an interesting place that we need more data on - it’s an area that drains a lot of the ice sheet and we want to monitor it,” said Koenig. These data will help track any thinning or acceleration of ice mass loss that may characterize the region. The DC-8 also undertook flights over Petermann, Humbolt, Rink and parts of Helheim and Kangerdlugssuaq Glaciers in southeastern Greenland.

Following the DC-8 survey, scientists handed off the equipment to the P-3 airplane. Whereas the DC-8 covered sea ice and coastal phenomenon, the P-3 primarily surveyed glacial flow lines at lower altitudes and along smaller grids. Based out of Kangerlussuaq, it continued to track ICESat orbit paths above the rapid-flowing outlet glaciers of Jakobshavn, Helheim, and Kangerlussuaq. This allowed the MCoRDS system to gather data in crevassed coastal regions and inland glaciers.

Flights

Photo 2: DC8 and P3 flightlights covered most areas of Greenland and parts of the Arctic. Photo Credit: NASA

The results of the IceBridge survey will help us understand rapid changes we are currently observing. On July 6th and 7th, 2010, a 2.7 square mile piece of ice detached from the northern portion of Jakobshavn Glacier. The glacier’s calving front has been retreating about three kilometers per year since 2001, nearly double its steady flow over the previous century. More recently, Petermann Glacier calved about one fourth of its floating ice shelf on August 5, 2010. The release constituted the formation of the largest iceberg in the Arctic since 1962.

In addition to tracking glacial characteristics and changes, IceBridge flights also helped validate the operating quality of the CryoSat-2 satellite after its launch. The European Space Agency launched the satellite on April 8 to monitor polar sea ice and glaciers. The DC-8 flew across the same flight lines near the North Pole as the satellite on April 20. Tandem data collection by the DC-8’s Airborne Topographic Mapper allowed scientists to test the accuracy of the satellite’s Synthetic Aperture Interferometric Radar Altimeter system. Furthermore, satellite remote sensing provides a profile of the glacial ice’s surface, which airborne radars can then augment by measuring below the surface of the ice.

Once processed, the ice thickness, snow coverage, and sea ice data gathered from IceBridge flights and satellites will allow scientists to assess how land-terminating glaciers, outlet glaciers, sea ice, and ocean temperature influence the overall change and composition of the Arctic region. NASA plans to continue monitoring ice and snow coverage at both poles until ICESat-II’s estimated launch in 2015.

To view a simulation of the ice phenomenon that IceBridge monitors, please click here!