Part of the National Oceanic and Atmospheric Administration (NOAA), the Hurricane Research Division (HRD) is charged with conducting scientific research into hurricanes and related tropical weather phenomena. For more than 50 years, the HRD has relied on theoretical studies, computer models, and NOAA hurricane research aircraft to advance the understanding and prediction of hurricanes and other tropical weather. In recent years, HRD has been using unmanned aircraft systems (UAS) in its efforts to reach previously unreachable areas to help forecasters better understand the strength of a storm. Recently, Increasing Human Potential spoke with Joseph Cione, a research meteorologist at HRD and the lead scientist of the project that aims to send UAS with weather-watching equipment deep into a hurricane.
How did the concept of utilizing UAS to monitor hurricanes come about?
Like most good things, it happened with a little bit of luck. NASA entered into a three-year cooperative agreement with Aerosonde in 2003, seeking to determine civilian uses and scientific research capabilities of using UAS. We were the first to propose using UAS to monitor and observe hurricane patterns. Our proposal was approved and we received flight hours with their Aerosonde platform. Shortly after, we started working with the Aerosonde crew that was stationed in Wallops Island, Virginia, and a year and a half later we were flying in a storm.
Your first successful operation in 2005 gathered real-time near surface wind and thermodynamic data from within tropical storm Ophelia. How have the technology and the results changed and improved since then?
Tremendously! The biggest change has to do with our concept of operation. In the past, we had sort of a land-launched system where we would get a team to the area to launch the UAS and hope it could make it within range to the storm. That became very problematic and expensive. Now, UAS are dropped directly from our manned aircraft, eliminating the time spent traveling from and back to base. This is a huge improvement in our ability to get into the storm. As far as technology goes, our UAS used to be a gasoline powered aircraft, but are now powered by an electric motor. In the last year or so we have gone from lasting around one hour in the air, to what we expect to be a two to three-plus hour duration as early as next year. This is huge. It will allow us to direct the UAS exactly where we want it to go, and allow for extended profiling and targeting of one area. We can now sample a lot quicker and get a lot more data per unit time. Before, we were looking at one hertz pressure temperature wind and humidity sensors, while we are now up to four hertz. We expect that number to increase with time as technology continues to improve.
Why is it beneficial to use unmanned in certain scenarios, as opposed to the regular aircraft? Are there scenarios where the two interact to make the research better?
I think manned aircraft and unmanned aircraft do very different things. They are complementary and work together to supply better research tools. If you only have manned aircraft, there are things you cannot do that UAS can. And if you only have UAS, particularly low-altitude UAS, there are many things that cannot be accomplished. For example, the Doppler radar system on manned aircraft gives a three dimensional volumetric structure to wind, which is critical to initializing and validating the model that predicts and tracks changes. Low-altitude UAS cannot do that. On the other hand, with UAS we can sample a much larger area and can spend longer periods of time in low areas, too dangerous for manned aircraft. UAS are one way we can measure thermodynamic structure within the hurricane, which is critical input for the numerical models we use to forecast intensity change.
Researchers have noted a lack of understanding in the way the ocean and hurricane interact. Why is this important, and how do you expect unmanned systems to fill this void?
Understanding air-sea interaction is critical and not well handled in the operational forecast models we currently use. To accurately depict the ocean-atmosphere environment for a hurricane, you have to have a comprehensive sampling strategy. If a given storm is to develop and intensify it needs a relatively warm ocean, but it also needs a conducive atmospheric environment. This lack of understanding is primarily due to the limited availability of detailed observations within the storm near the air-sea interface. UAS can fly 100 feet or so above the ocean and can look downward using moisture and temperature sensors. This gives us a much better understanding of the air-sea interface and thus a better idea of how much energy is coming out of the ocean. This is important because getting a more accurate and detailed low level atmospheric moisture field can help us make better forecasts. Recent studies and analyses tell us that current models are quite sensitive to atmospheric moisture conditions, especially at low levels in the hurricane. Much of our current knowledge of this region of the storm comes from ‘composite’ or averaged data from many storms. Given the forecast model’s sensitivity to these types of critical (and difficult to obtain) data, enhancements in this area should ultimately lead to improved forecasts and saved lives.
What are the different benefits of using low-flying UAS like the Aerosonde and high-flying UAS like the Global Hawks?
The biggest advantage of the Global Hawk is that it covers an enormous area. These UAS can fly more than 24 hours continuously at close to 65,000 feet. Our G4 jet, in comparison, can stay ‘on station’ for a maximum of 4-8 hours (depending on how far the storm is from the deployment location). The Global Hawk also has interesting and different remote sensing equipment that could complement what we already use with manned aircraft (both NOAA and Air Force). Low-altitude UAS like the Aerosonde and the Coyote sample the storm in high resolution but are more limited in area coverage due to their size. This class of UAS are primarily used to sample the difficult to observe, low altitude, high wind region of the hurricane that is typically inaccessible to manned aircraft. Right now low altitude observations we get from manned aircraft (e.g. GPS dropsonde, stepped frequency microwave, radiometer, Doppler radar) are essentially instantaneous measurements (think “snapshot” from a camera). In contrast a low flying UAS is continuously sampling winds, pressure, temperature, moisture and sea surface temperature. As such the low altitude UAS is giving us continuous measurements of this critical environment (think “movie”).
What is NOAA’s role in the NASA led hurricane and Severe Storm Sentinel (HS3) mission is? How has it contributed to the agency’s research?
This is a NASA-led effort in which we have been able to act as collaborators. Our main contribution to the program over the last few years has involved funding the Global Hawk dropsonde system. These are small devices designed to be dropped from the aircraft to collect atmospheric data while descending by parachute through tropical storms and hurricanes. We have also used our years of expertise in the area to assist in the planning of the operations, including where exactly to drop these measurement devices. Global Hawks add a tremendous amount of information around the storm and above 15,0000 within the storm. Currently manned flights within the core storm environment usually occur at altitudes below 15,000 feet while surveillance missions around the storm using NOAA’s GIV are typically conducted at approximately 42,000 feet. In contrast, the Global Hawk can fly at altitudes in excess of 60,000 feet around the storm and in most cases over the hurricane itself. Though Global Hawk UAS use mostly remote sensing technologies, the dropsonde system gives us some vertical profiling in areas we otherwise would not get to sample, especially in the core above 15,000 feet. In situ analyses using data from this region of the storm are essentially nonexistent, so as it relates to knowledge and understanding, many scientists are really excited about this new possibility.
How will NOAA use UAS during the 2013 hurricane season and what is the outlook for this year’s hurricane season?
We do not have plans to fly any low-altitude UAS in 2013. This year, as it relates to UAS, our main focus will be the HS3 NASA-led effort involving the high-altitude Global Hawk. We will work together with NASA and try to coordinate our manned aircraft to gather interesting and complementary data sets. We have partnered with the Navy to do a full blown experiment using the Coyote and our P3s in 2014. We are excited about this operation and hope to receive the appropriate funding for it. With regards to this year’s hurricane season, the National Atlantic Hurricane season outlook says there is a 70 percent likelihood of 13-20 main storms, out of which 7-11 could become hurricanes, and of those, 3-6 could become major hurricanes (111 miles or stronger). These ranges are well above the seasonal average of 12 main storms, 6 hurricanes and 3 major hurricanes.