Researchers are developing a system to predict the path and intensity of hurricanes by harvesting data from inside the storm itself. A team of UC San Diego controls engineers has been working with sensor-packed balloons that could be deployed in swarms to report back real-time data on temperature, pressure, humidity and wind speed from a squall for as long as a week.

The hope is that this new and relatively low-cost approach will improve tropical storm forecasting, which currently relies on different models that are often exceedingly vague, sometimes contradict each other, or just turn out to be wrong.

The engineers sought to create balloons that were small, durable, buoyancy-controlled and wouldn't accumulate ice. It was also important to be able to move the swarm in a coordinated fashion at altitudes up to 8 kilometers (5 miles) high in order to keep the balloons and their sensors adequately distributed over different regions of the storm.

"The helium-filled balloon is shaped like a large accordion with a pressurized interior and a winch-actuated cable running down the middle," UC-SD engineering professor Thomas Bewley explained to New Atlas. "The cable is pulled in or let out by the winch, which in turn changes the volume of the balloon, which changes its density. This causes the balloon to accelerate up or down in a highly controllable fashion."

Bewley and his team developed a model that takes advantage of the different winds at different levels of a hurricane to keep the balloons where they should be.

"The key idea of our large-scale balloon coordination strategy,"' said Bewley, "is to 'go with the flow,' commanding small vertical movements of the balloons and leveraging the strong vertical stratification of the horizontal winds within the hurricane to distribute the balloons in the desired fashion horizontally."

The balloons' controllers can correct the positioning of a balloon that "flows" too far from its desired course. A key part of the team's work is developing the algorithmic controls that take in data from the balloons' environment and also uses that information to keep them afloat and reporting back the right data.

The balloons carry "cell-phone grade" sensors, GPS, low-energy radios, satellite uplink equipment and a battery to keep them buoyant and transmitting for up to a week.

The next step will be to test the balloons and algorithms in the real world. Hopefully the system will eventually lead to less guesswork in anticipating where big storms might strike the shore, and a few days of additional lead time to prepare and evacuate.

Source: UC San Diego

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