(Conversation) – As Hurricane Ian strengthens on its way to the Florida coast, there are hurricane hunters in the sky to do something almost unimaginable: fly through the center of a storm. With each pass, scientists aboard these planes take measurements that satellites can’t make and send them to forecasters at the National Hurricane Center.
Jason Dunion, a University of Miami meteorologist, heads the National Oceanic and Atmospheric Administration’s 2022 field program. He described the technology the team uses to assess the behavior of hurricanes in real time and the experience on board P-3 Orion when it passes through the eye of a hurricane.
What happens aboard a hurricane fighter when you fly into a storm?
Essentially, we’re taking a flying lab into the heart of a hurricane, all the way up to Category 5s. As we fly, we process the data and send it to forecasters and climate modelers.
In Art P-3p, we usually cut through the middle of the storm right into the eye. A picture the X pattern – we continue to make our way through the storm several times during the mission. They may be developing storms or they may be Category 5s.
We are usually flying at about 10,000 feet, about a quarter of the way between the surface of the ocean and the top of the storm. We want to cut through the roughest part of the storm because we’re trying to measure the strongest winds for the Hurricane Center.
It should be intense. Can you describe what scientists feel during these flights?
My most intense flight was Darian in 2019. The storm was near the Bahamas and rapidly intensifies to a very strong category 5 storm with winds of about 185 mph. I felt like a feather in the wind.
As we passed through the Eye of Dorian, everything was on seat belts. You can lose a few hundred feet in a couple of seconds if you have a downdraft, or you can hit an updraft and gain a few hundred feet in a matter of seconds. It’s a lot like riding a roller coaster, except you don’t know exactly when the next high or low will come.
Even during a major storm, scientists like myself are busy with computers processing data. A technician in the back may have launched a probe from the belly of the plane, and we are checking the quality of the data and sending it to the simulation centers and the National Hurricane Center.
What did you learn about hurricanes from these flights?
One of our goals is to better understand why storms happen will soon intensify.
Rapid intensification is when a storm increases its speed by 35 mph in just one day. This means going from a Category 1 to a severe Category 3 storm in a short period of time. Ida (2021), Dorian (2019) and Mikhail (2018) are just a few recent hurricanes that have intensified rapidly. When this happens near the ground, it can catch people off guard and it quickly becomes dangerous.
Because rapid intensification can occur in a very short period of time, we need to be close to hurricane hunters taking measurements as the storm approaches.
While there is a rapid activation hard to predict. Perhaps we will begin to see the ingredients coming together quickly: the ocean is heated to great depth? Is the atmosphere nice and juicy, with lots of moisture around the storm? Are the winds favorable? We also look at the inner core: What does the structure of the storm look like and is it starting to consolidate?
Satellites can offer forecasters basic insight, but we need to send our hurricane hunters into the storm itself to really dissect a hurricane.
What does a storm look like as it rapidly intensifies?
Hurricanes like to stand upright – think of a pinwheel. So one thing we look for is alignment.
A storm that has not yet fully assembled may have a low-level circulation a few kilometers over the ocean that does not match its average level of circulation at an altitude of 6-7 kilometers. This is not a very healthy storm. But in a few hours we can fly into the storm again and notice that the two centers are more structured. This is a sign that it may intensify quickly.
We are also looking at boundary layer, an area directly above the ocean. Hurricanes breathe: they draw in air at low levels, the air rushes up toward the eyewall, and then exits at the top of the storm and away from the center. That’s why we get these huge updrafts in the eyewall.
So we can watch the data from our dip or tail doppler radar to see how the boundary layer winds are going. Is it really moist air that is intruding into the center of the storm? If the boundary layer is deep, the storm can also inhale more.
We also look at structure. Often a storm looks healthy on satellite, but we’ll go in with radar and the structure is sloppy, or the eye may be filled with clouds, telling us the storm isn’t quite ready to intensify quickly. But, during this flight, we can start to see the structure change quite quickly.
Air in, up and out – breathing is a great way to diagnose a storm. If this breathing appears healthy, it can be a good sign of an intensifying storm.
What tools do you use to measure and predict hurricane behavior?
We need instruments that measure not only the atmosphere, but also the ocean. Winds can make or break a storm, but the ocean’s heat and moisture are its fuel.
We use immersion probes to measure temperature, humidity, pressure and wind speed and send data every 15 feet or so all the way to the ocean surface. All of that data goes to the National Hurricane Center and the modeling center so they can better picture the atmosphere.
One p-3 has a laser – a CRL, or compact rotating Raman lidar – which can measure temperature, humidity and aerosols from the plane all the way to the surface of the ocean. This can give us a sense of how juicy the atmosphere is and how conducive it is to fueling a storm. The CRL runs continuously over the entire flight path, so you get this beautiful curtain under the plane that shows temperature and humidity.
Airplanes also have it tail Doppler radars, which measure how moisture droplets blow through the air to determine how the wind behaves. This gives us a three-dimensional view of the wind field, like an X-ray of the storm. You can’t get it from a satellite.
We also launch ocean probes called AXBTs – expendable air thermometer – there is a storm ahead. These probes measure water temperature several hundred feet. Generally, surface temperatures of 26.5 degrees Celsius (80 Fahrenheit) and above are favorable for a hurricane, but the depth of that warmth is also important.
If you have warm ocean water that might be 85 F at the surface, but only 50 feet below the water is slightly cooler, the hurricane will run into that cold water pretty quickly and weaken the storm. But deep warm water as we find in eddies in the Gulf of Mexico provides additional energy that can ignite the storm.
This year we are also testing new technology – small drones that we can launch from the belly of the P-3. They have a wingspan of 7 to 9 feet and are basically a weather station with wings.
Dropped into the eye, one of these drones can measure pressure changes that indicate whether a storm is intensifying. If we could drop a drone into the eyewall and point it into orbit, it could measure where the strongest winds are, another important detail for forecasters. We also don’t have many measurements in the boundary layer because it’s a dangerous place for an airplane to fly.
You also targeted the Cape Verde Islands off Africa for the first time this year. What are you looking for there?
The Cape Verde Islands are located in the hotbed of hurricanes in the Atlantic. The origin of hurricanes is away from Africa, and we are trying to identify the tipping points when these disturbances turn into storms.
More than half of the named storms we get in the Atlantic come from this nursery, including about 80% of major hurricanesso it’s important, even though the disturbance is perhaps seven to 10 days ahead of the hurricane.
In Africa, there are many thunderstorms along the southern border of the Sahara desert with colder, humid Sahel region in the summer The temperature difference can cause ripples in the atmosphere that we call tropical waves. Some of these tropical waves are harbingers of hurricanes. However, Art Sahara air layer – huge dust storms that come down from Africa every three to five days or so – can suppress a hurricane. These storms peak from June to mid-August. After that, tropical disturbances have a better chance of reaching the Caribbean.
At some point in the not-too-distant future, the National Hurricane Center will have to issue a seven-day forecast, not just a five-day forecast. We are figuring out how to improve early forecasting.