Observational Instruments
Hurricane observational instruments allow scientists to collect real-time data that improves the accuracy of hurricane forecasts and provides critical information for weather prediction models.
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Researchers at the Atlantic Oceanographic and Meteorological Laboratory (AOML) employ an array of instruments to gather data from inside hurricanes. These instruments range from flying drones to deep-diving gliders, and are each uniquely designed to capture a previously inaccessible dataset. The data collected by these instruments are vital for enhancing forecasters’ understanding of a storm’s behavior, and improving hurricane prediction models, leading to better preparedness and response strategies.
Aircraft
NOAA’s hurricane hunter aircraft are research stations with wings. The planes collect data using onboard instruments, as well as launch dropsondes, uncrewed systems, and other instruments into the storm. The P3-Orion flies directly into the storm, while the Gulfstream IV-SP flies overhead. The P3 flies back and forth across the eye, conducting multiple eyewall penetrations to gather data about wind speed, rain rate, and storm structure. The Gulfstream IV flies above the storm, collecting measurements from the atmosphere. The data gathered on these flights from both onboard and external instruments are crucial in improving hurricane forecasting, analysis, and modeling
Saildrone
Saildrones represent the intersection of atmospheric and oceanic observation instruments; their unique shape allows them to take measurements above and below the water. This data provides scientists with crucial information about the boundary layer where the ocean meets the atmosphere. During a hurricane, the sea surface within the boundary layer is subjected to strong winds and waves, making it inaccessible to boats or planes. Saildrones, however, can enter the storm due to their special hurricane wing and capture measurements of wind speed, wave action, air temperature, and temperature and salinity just below the ocean’s surface.
Understanding the boundary layer is important because it contains the conditions that will be experienced on the ground when a hurricane makes landfall. Accurate data from the boundary layer enhances storm impact predictions on coastal communities, enabling better preparedness and response efforts to protect lives and property.
Gliders
Gliders are autonomous underwater vehicles (AUVs) deployed during hurricane season to gather data to allow ocean conditions to be more accurately represented in hurricane forecast models. These observation instruments use small changes in buoyancy, along with wings for propulsion, to convert vertical motion into horizontal motion to swim and dive. This capability allows them to perform repetitive dives up to 1,000 meters deep, collecting temperature and salinity data.
Dropsondes
Dropsondes are the oldest hurricane observation instrument, and have been used since 1996. These instruments are launched from the bottom of the hurricane hunter aircraft to gather data inside the storm. After exiting the plane, a parachute deploys to slow its descent. As the dropsonde falls towards the ocean, sensors relay information about temperature, pressure, relative humidity, wind speed, wind direction, and dew point. In a given storm, researchers will release an average of 20-40 dropsondes along the flight track to gather real-time data at various points throughout the storm’s inner core and outer bands.
StreamSondes
StreamSondes are the newest addition to NOAA’s hurricane hunting kit. These ultra lightweight biodegradable instruments developed by Skyfora are released from the hurricane hunter P3 to gather atmospheric data. They lack a parachute and are significantly smaller than dropsondes, enabling scientists to deploy multiple sondes at a time. Streamsondes report pressure, temperature, humidity, and wind data. Sondes have been dropped in previous years, but the 2024 hurricane season marks the first year that Skyfora streamsondes will be released operationally in high numbers.
Uncrewed Aircraft System (UAS)
Uncrewed Aircraft Systems, commonly known as drones, have improved hurricane research by giving scientists the ability to study the boundary layer where the atmosphere directly interacts with the ocean’s surface. UAS released from the P3 aircraft stay aloft for hours at a time, collecting vital information on wind speed, humidity, temperature, and atmospheric pressure in the harshest conditions of a hurricane. This turbulent region influences the exchange of heat, moisture, and energy between the ocean and atmosphere. Understanding conditions within the boundary layer improves modeling efforts that forecast hurricane intensity and behavior.
Airborne Expendable BathyThermograph (AXBT)
Airborne Expendable BathyThermographs are another instrument launched from the belly of the hurricane hunter P3. This expendable does nothing until it hits the surface of the water, making it the only aircraft-deployed oceanic observation instrument. Once an AXBT hits the water, it measures ocean temperature as a function of depth. These observations give researchers an idea about how a storm passing overhead cools, mixes, or heats the ocean. AXBT data help scientists better understand the interactions between the ocean and the atmosphere during severe weather events. This information is crucial for improving hurricane intensity forecasts, as the thermal structure of the ocean significantly influences storm strength and development.
Argo Float
Argo floats drift with ocean currents and move up and down between the surface and a mid-water level. These floats are distributed all over the global ocean and are in place year-round to measure temperature and salinity in the upper 2,000 meters. During hurricane season, these deep-diving instruments can be caught in storms, offering valuable data about ocean mixing beneath the cyclone. They reach deeper than gliders, revealing the depths at which the ocean and atmosphere interact, crucial for understanding hurricane formation and development.
Drifter
When deployed, drifting surface buoys are tracked by satellites as they float through the ocean. They create a global network of data points that takes measurements year-round. These observational buoys measure mixed layer currents, sea surface temperature, atmospheric pressure, winds, waves, and salinity. Since the drifters are floating year-round, they can be caught in the ocean below a hurricane if the current pulls them towards a developing storm. When this occurs, researchers seize the opportunity to explore an entirely new data set – the ocean conditions inside a hurricane.