By Peter Whoriskey
Washington Post Staff Writer
Tuesday, October 3, 2006
BOCA CHICA KEY, Fla. -- Drones are better known for their role in pursuing military targets, but scientists here are poised to launch them into the raging vortexes of hurricanes.
The small, unmanned aircraft will explore the storms at low levels that are too dangerous for "hurricane hunter" aircraft to probe. Meteorologists hope the information gathered will provide new details about wind speeds at the Earth's surface and how a hurricane feeds itself on the warmth of the ocean.
"It's impossible for manned flights to fly at the levels we'd like because of the safety risks," said Joseph Cione, the National Oceanic and Atmospheric Administration's lead scientist on the pilot project. "This is the portion of the hurricane that we really don't know that much about."
The drones, known as Aerosondes, have a wingspan of 10 feet and can be launched from an automobile with the aid of a rooftop launcher. The car, with a launcher strapped to the roof, reaches about 60 mph, at which point the aircraft is released by a latch.
The planes are remarkably light, but also remarkably sturdy. An Aerosonde flew into Tropical Storm Ophelia last year, recording temperature, humidity and wind speeds.
Now the aim is for similar measurements from hurricanes. Five Aerosondes are waiting here for a hurricane to form. The $300,000 for the project comes from NOAA and NASA.
"If we lose the aircraft, that is part of the process," said Peter Bale, an Aerosonde representative.
Despite all the satellite and radar imagery available to scientists, what happens in the portion of the hurricane nearest the ocean is relatively undocumented.
The piloted hurricane hunter airplanes typically fly into hurricanes at 10,000 feet up, nearly two miles above the surface, sometimes dropping to as low as 5,000 feet. The risks rise as the planes descend.
The Aerosonde, by contrast, is expected to be able to drop to 500 feet or less over the ocean. The data collected are expected to provide immediate help for meteorologists trying to estimate a hurricane's wind speeds at the Earth's surface.
In the longer term, the information is also expected to help scientists better understand the air-sea connection in hurricanes and to make more accurate predictions of their intensity, one of the most urgent challenges facing meteorologists today.
While scientists have dramatically improved their understanding of the movement of hurricanes -- their storm-track forecasts have improved substantially -- predictions about intensity have lagged.
This season, Tropical Storm Ernesto was forecast to become a hurricane in Florida. Airports closed. Students in South Florida had two days off. But Ernesto's predicted fury never materialized -- the feared storm proved to be a meteorological dud.
The predictions have underestimated storms, too. In 2004, Hurricane Charley startled scientists when it blossomed from Category 2 to Category 4 in a very short time.
"Why did that happen? Scientifically, we really don't know," Cione said.
While scientists know that hurricanes derive their power from the warmth of the ocean, what's far less clear are the conditions at the point where the hurricane touches the ocean, which is where the energy transfer takes place.
For example, scientists had long assumed that the difference between air temperatures and ocean temperatures were small -- less than 1 degree Celsius. But recent research by Cione and others, based on ocean buoys that just happened to be under a hurricane, showed that the temperature difference has been two or three times that.
The significance of the temperature difference is "huge," Cione said, because the amount of energy flowing from the water into the hurricane partly depends on it. The drones, he hopes, will render more clues about this portion of the hurricane.
While scientists have reams of satellite and other data collected from storms, little of it provides even basic information about the nexus of the air and ocean.
The Aerosondes can stay aloft for as long as 20 hours. Sensors on the wing will transmit basic meteorological information to the National Hurricane Center and NOAA's Hurricane Research Division about what is happening at the stormy surface.
According to a NOAA statement: "Continuous observation of temperature, moisture, and wind structure of the near-surface hurricane environment has never been documented in a hurricane."