Black Swift Technologies discusses how the National Oceanic & Atmospheric Administration (NOAA) used the company’s Black Swift S0 UAS for boundary layer observations of tropical storms.
Understanding the behavior of the lower boundary layer of tropical storms is a critical area of research for the National Oceanic & Atmospheric Administration (NOAA) Atlantic Oceanographic and Meteorological Lab. The next step to improving hurricane forecasts might just be in the form of a three-pound aircraft.
In March 2023, NOAA’s hurricane research toolset grew with the successful clear air deployment of the Black Swift S0 UAS (Uncrewed Aircraft System), a purpose-built aircraft designed specifically for boundary layer observations in turbulent environments (Figure 1).
Since the mid-70s, NOAA scientists have relied heavily on crewed aircraft such as the Lockheed WP-3D Orion four-engine turboprop aircraft (Figure 2) to collect essential meteorological data to gain a better understanding of storm processes, in an effort to improve their forecast models.
Yet this approach has its limitations. As Joseph Cione, Lead Meteorologist for New Technologies at NOAA’s Atlantic Oceanographic and Meteorological Lab states, “Since our P-3’s have people on board, we can’t fly where the winds are the strongest, where the turbulence is the greatest—at altitudes below ten thousand feet. We’re never going to risk flying a P-3 down low.”
So how does the agency strive to overcome this reality?
“We leverage technology, specifically drones that can withstand these extreme conditions and sample the lowest region of the storm for long periods of time (an hour or more),” says Cione.
The interface of the atmosphere and the ocean is critical in understanding how the storm works, how it gets its energy, and how the momentum of the storm is transferred to the sea. UAS or drones are proving themselves to be the platform of choice to gather this information. As Cione elaborates, “Our goal is to build a technology toolbox enabling us to deploy the UAS platform best suited for the circumstances we encounter.”
“This is a crawl, walk, run kind of business,” states Cione. “It takes time to make advances when you are referencing emerging technologies. The hurdles companies must overcome are substantial.”
One of the first challenges developers face is to demonstrate safe separation, the ability to launch the UAS without damage to the drone or the P-3. The UAS needs to survive ejection at more than 200 knots and deploy as expected. Some might think this is trivial, but to have a sub-4-pound UAS survive and operate under these extreme conditions is a big achievement. In their initial flight test, Black Swift Technologies proved their aircraft worthy of the task.
Next, the aircraft must demonstrate that it can effectively capture and transmit essential data to the P-3 in real-time. The approach that Black Swift took to address this requirement was to relay all essential data over to a system that mimicked the capabilities of the Advanced Vertical Atmospheric Profiling System (AVAPS)—a real-time data system NOAA uses extensively with their dropsondes.
And can the UAS stay in the air as long as advertised? The defined objective for the Black Swift S0 was 1-hour. For recent clear air testing the S0 stayed aloft for 83 minutes, with the final 20 minutes at an altitude of only 10m (30 ft) above the ocean.
And finally, can the UAS operate and transmit at a significant range from the host aircraft? The Black Swift S0 performed as expected in the initial flight test, out to a range of 35 miles.
“Overall, I was quite pleased with the performance we saw,” Cione reports. “We’re past the crawl stage. We’re upright and walking. We’re not running yet, but I’m confident we’ll make it to that stage.”
A Radical Approach to Data Capture
Critical to the success of the S0 UAS platform was Black Swift’s ability to reduce the complexity and weight of the vehicle compared with existing platforms, offering an order of magnitude decrease in cost while maintaining endurance without sacrificing performance and measurement quality.
The Black Swift S0’s design enables fully-autonomous high resolution atmospheric thermodynamic measurements at altitudes up to 15,000 feet AGL. The sensor suite incorporated in the aircraft allows the S0 to quickly and accurately capture 3-dimensional wind profiles, air and sea temperatures, wind speed and direction, dewpoint, and atmospheric pressure at various levels in the atmosphere.
A key component to the sensor package found on the Black Swift S0 is the multi-hole probe designed by Black Swift Technologies. The Black Swift SwiftFlow 3D Wind Sensor captures not only differential pressure measurements, but its magnetometer and Inertial Measurement Unit (IMU) coupled with fusion algorithms provide a full wind vector solution. A tightly integrated multi-hole probe and wind velocity measurement device, the Black Swift SwiftFlow accurately records air speed, altitude, angle-of-attack, side-slip, ambient temperature, and relative humidity for a more comprehensive capture of the wind environment and accurate evaluation of an aircraft’s performance.
“We designed two versions of our SwiftFlow Wind Sensor,” explains Jack Elston, Ph.D., Founder and CEO, Black Swift Technologies. “What is significant about this probe is the fact that we incorporated a wind sensor that sits flush on the nosecone of the plane (no probe tips sticking out) which provides high frequency (100Hz) 3D wind measurements, including vertical wind speed, which most people can’t estimate—and if they do, it’s usually error prone. Not only that, but we found a way to make it work in all weather conditions.”
“I was impressed with BST’s multi-hole probe when I was introduced to it, that I suggested that they port this unique technology over to other platforms. To my knowledge, this probe is the smallest, most cost-effective multi-hole probe on the market.” Cione said. “Now we have Black Swift’s multi-hole probe on both the Altius and the S0. This is another great example of synergy between these two groups.”
It All Comes Down to Physics
To understand the significance of the measurements made by Black Swift’s S0 UAS is to understand the physics of computer models. Researchers need to ascertain how energy is transferred from the ocean, and how the resulting momentum is transferred from the storm to the ocean or the land as the storm makes landfall. This process can be better understood by assessing quantities known as fluxes—both the flux of momentum and the flux of heat and moisture. In computer models, these fluxes cannot be ascertained directly so they are estimated using what are known as transfer coefficients. These values are essentially a catch-all parameter that includes a lot of uncertainty. One of the goals of the NOAA ongoing project is to reduce this uncertainty. Given there hasn’t been an effective way to capture and accurately measure this information, transfer coefficients have proven to be a difficult element for researchers to pin down.
“With the turbulence probes Black Swift has developed, we have an opportunity to measure atmospheric fluxes directly using eddy covariance techniques that don’t require transfer coefficients,” says Cione. “In order to measure fluxes directly near the surface, turbulent quantities that can be measured with the S0 multi-hole probe need to be obtained within a couple of hundred feet from the ocean surface where winds can exceed 150 miles an hour. Until the introduction of these two UAS platforms that include these special sensors, there hasn’t been a way to gather this type of unique data.”
“If we are able to measure these fluxes directly in high wind storm conditions, we may be able to significantly reduce the uncertainty associated with these coefficients,” Cione clarifies. “If the platforms can survive extreme storm conditions and collect the data we need, it could help improve future forecasts of intensity change—or how strong a storm is likely to become. This is sort of the holy grail of boundary layer, high wind Tropical Cyclone research. For me personally, this has the potential to be one of the most exciting developments associated with this research.”
Observations from small uncrewed aircraft have the potential to enhance scientists’ basic understanding of dangerous and difficult to observe regions of a Tropical Cyclone. Understanding the interactions occurring between the air and the sea is critical if researchers are to better understand how the storm works, how it gets its energy from the ocean, and how the momentum from the storm is transferred back down to the sea. Near-surface wind observations collected from these platforms have the potential to significantly improve situation awareness as well as the performance of future operational forecasting models. Understanding how the near-surface environment of the hurricane draws energy from the ocean can help scientists better assess if and how much a Tropical Cyclone is likely to develop, predictions that could save lives and reduce the devastating economic impacts these storms have on society.
Having the Right Tool for the Job
Cione and his team at NOAA have developed a number of research modules, one of which is called the RICO SUAVE (Research In Coordination with Operations of Small Uncrewed Aircraft Vehicle Experiment). Here, researchers utilize what is referred to as an inflow experiment requiring two to three hours of flying in a spiral pattern into the storm, eventually getting to the eyewall. The Altuis is well-suited for this type of deployment. Another approach that Cione describes as the Eyewall Experiment is where the UAS does a center fix in the eye of the storm, flying round and round in the eyewall for up to an hour and a half—a task the S0 is well-suited for.
“These are just two examples where one platform can do one thing and the other platform could do something slightly different,” Cione mentions. “There are a lot of use cases for both systems. This is the type of diverse toolkit that gives us as many options and backups as possible.”
“Our goal is to build a technology toolbox,” adds Cione. “Currently, the Altius can fly longer with an endurance of up to four hours, whereas the S0 has the advantage of being lighter, smaller, and less expensive. The S0 measures turbulence a little differently due to its smaller size. You never know which platform is going to work best in certain circumstances. That is why we continue to test both aircraft.”
“It’s always better to have multiple platforms instead of one, because if you only have one small UAS and it fails, you have nothing,” Cione elaborates. “These systems are good backups to each other, and they also serve different needs.”
Technology will continue to play a greater role in NOAA’s Hurricane Research. Whether the advances are in airframes, guidance systems, sensor suites, or new and emerging technological developments, the status quo is never good enough. NOAA’s goal of capturing the data necessary to help emergency managers make informed decisions on evacuations before tropical cyclones make landfall, can save lives as well as reduce the economic impact associated with these storms.
Cione’s goal for NOAA is to transition small UAS technology into routine hurricane operations, similar to those of dropsondes which have been used for decades.
“Eventually we want to regularly conduct sUAS missions into Tropical Cyclones,” elaborates Cione. “We’re not there yet. It’s going to take a few more years, but I’m confident we will eventually realize this vision.”
Despite not yet being earmarked for regular use, the S0 can start making an impact on hurricane forecasts starting fall 2023. Data collected during the flights will be relayed in real-time from the P3 to the National Weather Service and ingested into their models.
“It’s been several long years developing this capability and we’re incredibly excited to start seeing it make an impact,” says Elston. “We have a future vision where several of our S0 UAS can be launched at once, self-organize, and use model-based flight control to fill in data gaps all on their own. Until then, even this single vehicle generation which requires operator oversight has a real chance of delivering data never before gathered on a regular basis. Hopefully that will lead to longer lead times and ultimately save lives.”
Black Swift Technologies will be at Xponential 2023 – visit them at Booth 3616 to find out more