Yungel – Operation IceBridge

Scientific Snapshots: Using IceBridge Data in the Field

By George Hale, IceBridge Science Outreach Coordinator, NASA Goddard Space Flight Center

Every IceBridge flight adds to a growing collection of geophysical data. Gigabytes of information on surface elevation, ice thickness and sub-ice bedrock topography are collected, but collecting the data is only the beginning of the job. After each campaign, information is downloaded from the instruments and processed to be delivered to the National Snow and Ice Data Center in Colorado, who store IceBridge data and make it freely available to the public.

Preparing data to send to NSIDC is a long and painstaking process, usually taking about six months. Before even starting data processing for the Airborne Topographic Mapper, IceBridge’s laser altimeter instrument, it’s necessary to calculate aircraft position and attitude and even mounting biases on ATM’s laser itself. “Once all the calibrations take place, the processing of all the ATM lidar data can take place,” said ATM program manager Jim Yungel. After that, processing to remove returns from clouds and ice fog and quality checking takes place. And because there are two ATM lidars, one narrow-band and one medium-band, this process is done twice and the results are compared.

But sometimes researchers want a visual representation of something interesting in the field. By combining lidar data with rough GPS trajectories and information from the aircraft’s inertial navigation system, researchers like Yungel can use a custom-built graphics program to create visual representations of the ice. These snapshots of the surface aren’t meant to be precise, but to give IceBridge scientists a rough idea of what was seen, and when combined with images from the aircraft’s Digital Mapping System, it’s easy to see side-by-side, a representation of what information the instruments collect. Below are a few representations of features seen during 2012 Antarctic campaign flights.

A graphical representation of processed Airborne Topographic Mapper data from the 2011 Antarctic campaign showing the rift in Antarctica’s Pine Island Glacier. Credit: NASA / ATM Team

Animation showing ATM data representation of Pine Island Glacier rift and images from the Digital Mapping System
Animation showing a 2012 ATM data representation of Pine Island Glacier rift and images from the Digital Mapping System. Credit: NASA / ATM and DMS teams

Crevasses in a glacier seen from the DC-8 near the Ronne Ice Shelf on Nov. 1. Credit: NASA / Jim Yungel

ATM data representation of the glacier crevasses seen on the Nov. 1, 2012 flight. Credit: NASA / ATM

IceBridge Over the Desert

By Claire Saravia, NASA Goddard Space Flight Center Office of Communications

Before the instruments aboard NASA’s Operation IceBridge fly over Antarctica in October to collect polar ice data, they will be tested over an unlikely ice substitute: a series of sites in the Mojave Desert.

The instruments that are part of IceBridge—a six-year flight mission designed to study ice at the Earth’s poles and bridge the gap between the two ICESat missions —are put through test flights every year to ensure they’re functioning properly.

This year, instruments like the Airborne Topographic Mapper (ATM) will use three separate sites in the California desert as a dress rehearsal for one of the real mission flights.

View of the Mojave Desert from the DC-8. Credit: NASA/J. Yungel

While it might seem counterintuitive to use a desert to simulate land filled with ice, ATM scientist John Sonntag said the area’s land features and reflective sand produce a similar landscape.

“The variety of terrain and surface reflectance over these lines will allow us to adjust the ATM for a wide variety of targets, thus increasing the reliability of the system once we get over Antarctica,” Sonntag said.

The IceBridge mission scientists aren’t the first to use the dry, sandy area to portray its icy counterpart. Sonntag said the test flight would be using some of the same tracks used during test flights of the ICESat mission as a way to compare measurements.

“We continue to overfly these tracks as part of ATM calibrations because we can compare the results with over flights of those same targets in previous years,” Sonntag said. “These comparisons will allow us to adjust the calibration parameters of the ATM with great precision.”

One of the desert features that will be used in the test flight is the El Mirage dry lake, which Sonntag said is frequently featured as a scenic backdrop in both movies and car commercials.

“El Mirage is a nearly ideal site for doing these laser calibrations because it is large, relatively flat, completely unobstructed by overhead features such as power lines and light poles, and has a bright laser reflectance similar to snow and ice,” Sonntag said.

The El Mirage dry lake in the Mojave Desert. Credit: NASA/J. Yungel

While it would be more ideal to use actual snowy surfaces to test the instruments, ATM program manager James Yungel said the easy access to sand regions outside both the NASA Wallops Flight Facility and the Dryden Flight Research Center made it the next best thing.

“Finding snow near Wallops or Dryden when we install on the aircraft can be difficult, but both NASA home airports have sand beaches or sand desert regions that are fairly close to snow reflectivity,” Yungel said. “These sandy sites allow us to tune the ATM systems for actual snow targets.”

IceBridge project scientist Michael Studinger said the fact that the scientists know the desert sites well makes them a popular spot for adjusting the instruments to measure ice.

“This is necessary so that we can collect high quality data over unknown targets like the Antarctic ice sheet and be confident that we have an extremely precise measurement of the ice surface elevation,” Studinger said. “It’s not about the precise location, but calibrating the radar for the signal that is transmitted from the antennas and then reflected back from the layers in the ice sheet and glaciers.”

IceBridge conducted two equipment checkout flights, one over the Pacific Ocean on Oct. 2 and one over the Mojave Desert on Oct. 3. The IceBridge Antarctic campaign is scheduled to begin with its first science flight on or about Oct. 11, 2012.

Zachariae and 79 North

The IceBridge flight on Tuesday, March 30, marked the first of a four-flight series to measure the Zachariae and 79 North glaciers in northeast Greenland. The flight made six parallel passes up and down the uppermost, inland portion of the glaciers. The beds of these glaciers are below sea level, which has implications for how the glaciers interact with ocean water and how they lose ice. The planned part of the survey concluded early, so the crew decided on-the-fly to add two extra flight lines — one pass down the middle of each glacier. Jim Yungel, of NASA’s Wallops Flight Facility, captured a series of photos throughout the low-altitude flight:

The actual flight path, including two extra flight lines down the middle of the glaciers.

Thule plow and sweeper clear the ramp and taxiway before the flight. Credit: Jim Yungel/NASA’s Wallops Flight Facility

Nunataks — hills or mountains encircled by a glacier — are seen among the ice. Credit: Jim Yungel/NASA’s Wallops Flight Facility

Glacial blocks are seen near Zachariae Glacier. Credit: Jim Yungel/NASA’s Wallops Flight Facility

A close up view shows details within glacial blocks seen near Zachariae Glacier. Credit: Jim Yungel/NASA’s Wallops Flight Facility

The science team and a NASA video producer watch the glacier. Credit: Jim Yungel/NASA’s Wallops Flight Facility

Preliminary data from the Airborne Topographic Mapper (ATM) show the topography around the Zachariae Glacier calving front region. The image contains preliminary data and is not for scientific analysis. Credit: Rob Russell/ATM team