The Lamont IcePod team is a blended mix of engineers and scientists learning from each other through the design and testing of this new instrument. With a range of talents and backgrounds, the project mixes seasoned field workers with those new to field work; experienced instrument developers with those newly learning this end of engineering; and scientists with countless hours spent pouring over Greenland ice sheet data with those exploring the ice sheet for the first time. It is the opportunity for mentoring and development that comes from this mix of early career with experienced personnel that has made the IcePod Instrument Development Project a good fit for its American Recovery and Reinvestment Act funding.
So who makes up the IcePod engineering and science team? As we work through data and examine the products collected in the first part of our field season there is an opportunity to introduce members of the team and the data and instruments they operate.
Chris Bertinato trained as an aerospace engineer before joining the IcePod team. In the air he is the team’s connection to the flight decisions made by the crew. Like the members of the flight crew he dons a headset as soon as aircraft begins its warm up. The headsets are connected into the plane electronics through lengthy cabling that trails behind each set. The cabling necessitates a threading and weaving between the crew as they move about the aircraft, testing and checking equipment and switches. Watching them work one can imagine a class devoted to practicing safe maneuvering about the plane while tethered to the electronics system – something like a Maypole dance!
Chris is a main operator of the equipment rack and has responsibility for the Laser Imaging Detection And Ranging (LIDAR) system part of the optical package in the pod taking constant measurements to find the surface elevation, and the inertial navigation system (INS) used to locate or “georeference” the data. The INS is a critical navigation aid that employs several accelerometers (motion sensors) and gyroscopes (rotations sensors) to continuously calculate the position, orientation, direction and speed of the plane as it moves through space. INS were first developed for rockets, but have become essential instruments for collecting referenced data in an aircraft, since the pitch, roll and yaw of the plane (see drawing) as it moves through the air can make it difficult to correctly locate and orient the data for processing. For those of us used to flying on commercial airliners, movies and music can provide enough of a distraction that we don’t notice the regular rolling of the aircraft as it responds to buffeting by the air around it.
The cylindrical housing for the laser sits snugly in one of the pod bays with the INS sitting atop in the small grey box. The laser focuses down through a clear panel, and scans back and forth in a swath that at 3000 ft. of altitude swings approximately 3000 ft. wide collecting elevation information. The data is then fed through a processor that turns it into elevation data.
The image above shows a swath of laser data over the airbase, and can be used to help explain the instrument. The color in the image shows the reflectance of different surfaces to the laser. You will see three of the LC130 aircraft lined up across the front of the airfield, cleaned from snow and clearly outlined in the data. There are two additional aircraft positioned in the middle of the image that are still surrounded by snow and therefore remain somewhat obscured. Trees, roads and other features in the adjacent area are clearly imaged.
In Greenland Lidar will be used to assist with locating features of interest in the ice sheet. The image above of meltwater channels in Greenland will be important to track during the summer season as these channels can reactivate seasonally, becoming a blue stripe on the otherwise white landscape. These darkened blue sections will absorb more heat energy from the sun due to their altered reflectivity (albedo) encouraging additional surface melt. In an upcoming post we will discuss how the infrared camera carried in the pod will allow us to track the heat energy in the channel both in its current state, and as it begins to melt later in the season.
Lidar will also be used to detect openings in the ice sheet (crevasses). Many of the crevasses are deep yet not wide, making them difficult to detect without the assistance of instruments. Detecting crevasses is important as they pose danger for pilots attempting to land and deliver support to ground crews, can be deadly for overland traverses that are carry scientists and support staff across the ice, and can provide us with critical information on changes in the ice sheet. Lidar data collected in our IcePod flights can be used to help in all of these situations.
For more on the IcePod project: http://www.ldeo.columbia.edu/icepod