The Integrated Remote and In Situ Sensing (IRISS) initiative was established to collaborate with research scientists to enable new ways to make valuable measurements using unmanned aircraft systems.
This past April, IRISS was able to apply the capabilities of its unmanned aircraft to atmospheric sampling in the Arctic in the Evaluation of Routine Atmospheric Sounding Measurements using Unmanned Systems (ERASMUS) project, funded by the US Department of Energy (DOE).
Along with researchers from the Cooperative Institute for Research in Environmental Sciences (CIRES), the IRISS team made their way to the DOE Atmospheric Radiation Measurement (ARM) Mobile Facility in Oliktok Point, Alaska to study the arctic haze in spring. The goals of the expedition were threefold: 1) To determine the reflection and absorption of solar energy in different layers of the atmosphere and on various surfaces of the Earth; 2) To measure the size of aerosol particles at different layers of the atmosphere; and, 3) To demonstrate the ability of unmanned platforms in a harsh and unforgiving environment. These types of measurements have been taken before with manned aircraft, though at higher elevations and over larger spatial scales, which led to confounding factors that made it challenging to correlate any specific phenomenon with the measurements obtained. Equipped with a one-of-a-kind cloud particle spectrometer built in the NOAA Chemical Sciences Division , broadband radiometers on loan from Pacific Northwest National Laboratory (PNNL) and thermodynamic sensors supplied by the National Center for Atmospheric Research (NCAR), the unmanned aircraft system was able to fly as low as 100 meters over a variety of terrains, including the arctic tundra and sea ice.
The team was able to gather valuable data, but the expedition was not without challenges. The sub-zero temperatures, which, with windchill, reached below -30° F (-34.4° C), was an exceptional issue. At temperatures that low, the plastic parts on the drone became very cold and brittle and there was concern they may malfunction or break.
Doug Weibel, Senior Research Professional at IRISS, spoke of the extreme cold, strong winds, and risk of polar bears.
Weibel: “[Our] biggest challenge was that it’s a difficult environment to do things in. You have to think through a lot of problems that you don’t necessarily worry about [in Boulder]. Things like we’re flying this aircraft that runs on batteries and at some point we have we have to transfer the batteries outside and put them in the plane and get everything to the runway, so how cold are the batteries going to get in that time because that’s going to impact their performance. Things like are [we] going to have a problem with airspeed sensors being clogged with snow before takeoff.”
CIRES research scientist Gijs de Boer, the project’s principal investigator, added additional insight into the importance of this mission:
de Boer: “Observations at high latitudes are generally sparse. This is particularly true for profiles of critical quantities. Manned aircraft do make their way up to the Arctic on occasion for intensive operations periods, but they generally don’t like to fly too low and they cover large amounts of area at high speed. However, measurements providing a more localized perspective are sorely needed, particularly around the limited number of atmospheric ‘super-site’ observatories that make continuous measurements of clouds, aerosols and radiation, and particularly in the layer between the surface and lowest clouds (0-1000 m). ERASMUS was designed to provide a first look at making such measurements on a more routine basis using unmanned aircraft.”
Despite the challenges, the team was able to collect data in layers of the atmosphere between 100-150 meters above the terrain. As the unmanned aircraft was able take samples over multiple geographic features closer to the surface, researchers may be able to make stronger correlations between the phenomena and the variations in the terrain. Weibel hopes these data will “help understand drivers of weather phenomena and drivers of climate as a whole.”