Unmanned Aerial Systems Propel Atmospheric Science Forward

Newswise — High in the sky over an Alaskan tundra, a small aircraft ran the same pattern over and over again. It swooped through clouds and flew down close to the ground. But there were no people experiencing the flight from inside the plane – it was an unmanned aerial system (UAS). UASs are aircraft that people can operate remotely from the ground. Building on years of testing, researchers working with the Atmospheric Radiation Measurement (ARM) Department of Energy Office of Science user facility are now gaining access to these helpful tools. 

To understand our atmosphere’s complex processes, researchers must take data in the field – a lot of data. These data can include air temperature, pressure, humidity, windspeed, trace gases, and information about tiny particles in the air called aerosols. Scientists also rely on observations from instruments on the ground, ones brought up in tethered balloon systems, and in aircraft flown by a human pilot. 

UASs expand the options for data collection. UASs are particularly good for gathering data in hard-to-reach places, like over ice or the ocean. Unlike planes crewed by people, UASs can fly slowly and relatively low to the ground. In addition, researchers can program UASs to run very specific patterns multiple times. These characteristics make UASs especially good for taking data on how properties in both the atmosphere and on the surface can differ over a geographic area. As UASs can be managed with only a few staff members, they are also less expensive to operate than crewed aircraft. 

ARM has been running and testing various UASs for decades. In the 1990s, the ARM team, led by DOE’s Sandia National Laboratories, ran a number of flights with different forms of uncrewed aircraft. 

A more recent research campaign was the Evaluation of Routine Atmospheric Sounding Measurements using Unmanned Systems (ERASMUS) campaign in 2015 and 2016. Based in Oliktok Point, Alaska, the campaign took extensive data on the Arctic atmosphere. Because climate change is affecting the Arctic faster than anywhere else in the world, it’s especially important to take data there. Researchers from the University of Colorado, Sandia National Laboratories, National Oceanic and Atmospheric Administration (NOAA), NASA, and DOE tested a type of small aircraft called the DataHawk. At just under three pounds each, these planes were downright tiny! But they packed a lot of punch. In that small space, researchers managed to fit sensors for taking data on location, altitude, pressure, temperature, humidity, and windspeed. The 3-foot wingspan allowed the DataHawk to fly up to almost 2 kilometers above the ground. Its benefits included being easy to set up and relatively low-cost. The campaign also tested a slightly larger UAS that could handle more instruments. After the ERASMUS campaign wrapped up, the ARM user facility used the DataHawk USAs for another two years. 

Meanwhile, the ArcticShark came onto the scene. This UAS is substantially larger than the DataHawk, with a 22-foot wingspan and the ability to carry up to 100 pounds of instruments. Made of composite, wood, and aluminum, the plane can operate at up to 18,000 feet with a research speed of about 70 nautical miles per hour. The name comes from its ability to run in the harsh conditions of the North Slope of Alaska. The ARM team started flight testing the ArcticShark in the spring of 2017. 

While the ArcticShark was named for its ability to handle the severe weather of Alaska, it certainly isn’t limited to that area. 

The ARM team began testing the ArcticShark at its Southern Great Plains (SGP) site in Oklahoma and the Pendleton UAS Range in eastern Oregon in 2021. In Oklahoma, flying 13 miles to and from a nearby airport to the SGP site, ARM initially had observers on the ground to track it visually. Those observers ensured that it was flying safely. The craft flew specific flight patterns to collect different types of data, including flying more than 1,000 feet above the ground. In these test flights, the team took a wider variety of data, including carbon dioxide trace gases, properties on aerosols, and surface images. 

Instead of using ground-based observers, later tests used a chase plane that followed the ArcticShark. This new tactic allowed the team to expand the area covered from 29 to 380 square miles and more than double its flight altitude. 

The testing was a success! Across all of the tests, ARM found that the accuracy of the instruments was comparable to the data taken by their now-retired Grumman Gulfstream-159 (G-1) aircraft. The tests also demonstrated that the team could operate this larger UAS safely. All of the data from these tests is available online on ARM’s website. Scientists can use these data to improve our understanding of atmospheric processes and computer simulations of our climate and Earth systems. 

With three test missions of the ArcticShark at the Southern Great Plains site completed, ARM is opening the ArcticShark up for researchers to use. Scientists are now envisioning what they could do with a UAS to support their research. The success of work that uses UASs is allowing atmospheric research to take flight more than ever before!